vendredi 19 septembre 2008

Lyra 7

Gamma Lyrae (γ Lyr / γ Lyrae) is a star in the constellation Lyra. It also has the traditional names السلحفاة Sulafat or Sulaphat (arab. "turtle"), or Jugum (lat. iugum, "yoke, Kummet").
It has spectral class A0 and is of magnitude 3.3.
Gamma Lyrae is approximately 635 light years from Earth.
Coordinates (epoch J2000):
Right ascension: 18h58m56s
Declination: +32°41'22"
Beta Lyrae (β Lyr / β Lyrae) is a binary star system approximately 882 light-years away in the constellation Lyra. Beta Lyrae is traditionally named الشلياق Sheliak which is Arabic for "tortoise" or "harp." Beta Lyrae is an eclipsing contact binary star system made up of a blue-white dwarf (B7V) star and a white main sequence (A8V) star. The two stars are close enough that material from the photosphere of each is pulled towards the other, drawing the stars into an ellipsoid shape. Beta Lyrae is the prototype for this class of eclipsing binaries, whose components are so close together that they deform by their mutual gravitation.
Beta Lyrae changes its apparent magnitude from +3.4 to +4.6 over a period of 12.9075 days. The two components of the main star are so close together that they cannot be resolved with optical telescopes, forming a spectroscopic binary.
The system also has a third star, at an angular distance of 45.7", which is of spectral type B7V and has an apparent magnitude of +7.2 and can easily be seen with binoculars. It is about 80 times as luminous as the Sun and is also a spectroscopic binary with a period of 4.34 days. There is also another star that appears to be in the Beta lyrae system, F, magnitude 9.9v separation 86" and luminosity 7 times that of the Sun.
Eta Lyrae (η Lyr / η Lyrae) is a star in the constellation Lyra. It also has the traditional name Aladfar (Arabic for "claws").
Eta Lyrae belongs to spectral class B2.5IV and has apparent magnitude of +4.39. It is approximately 1040 light years from Earth.
Coordinates (equinox J2000.0)
Right ascension: 19h13m45.50s
Declination: +39°08'46.0"

Lyra 6

Vega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus. It is a relatively nearby star at only 25.3 light-years (7.8 pc) from Earth, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.
Vega has been extensively studied by astronomers, leading it to be termed, "arguably the next most important star in the sky after the Sun". Historically, Vega served as the northern pole star at about 12,000 BCE and will do so again at around 14,000 CE. Vega was the first star, other than the Sun, to have its photograph taken and the first to have its spectrum photographed. It was also one of the first stars to have its distance estimated through parallax measurements. Vega has served as the baseline for calibrating the photometric brightness scale, and was one of the stars used to define the mean values for the UBV photometric system.
This star is relatively young when compared to the Sun. It has an unusually low abundance of the elements with a higher atomic number than that of helium. Vega is also a suspected variable star that may vary slightly in magnitude in a periodic manner. It is rotating rapidly with a velocity of 274 km/s at the equator. This is causing the equator to bulge outward because of centrifugal effects, and, as a result, there is a variation of temperature across the star's photosphere that reaches a maximum at the poles. From the Earth, Vega is being observed from the direction of one of these poles.
Based upon an excess emission of infrared radiation, Vega has a circumstellar disk of dust. This dust is likely the result of collisions between objects in an orbiting debris disk, which is analogous to the Kuiper belt in the Solar System. Stars that display an infrared excess because of dust emission are termed Vega-like stars. Irregularities in Vega's disk also suggest the presence of at least one planet, likely to be about the size of Jupiter, in orbit around Vega.

Lyra 5

The lyre is one of the most ancient of musical instruments. For example, in the royal city of Ur (circa 3000 BC) musicians played the lyre for royalty, according to excavated artifacts.
In Greek mythology, the lyre was invented by Hermes. When only a child, he pulled a cow-gut across a tortoise shell, and thereby created the lyre. Hermes gave this lyre to his half-brother Apollo (both were fathered by Zeus). As the god of music, Apollo became associated with the instrument.
Orpheus was given the instrument by Apollo when only a child, and the Muses taught him to use it. Even Nature herself would stop to listen, enraptured by his music.
When Eurydice, the wife of Orpheus, died from a snake bite and was taken to the Underworld, Orpheus followed in hopes of bringing her back. His playing convinced Hades to release Eurydice, providing Orpheus didn't look back at her during the journey home - but just as he emerged into the sunlight Orpheus turned and gazed upon his wife, and lost her forever.
There are several versions about the death of Orpheus. In the most widespread version Dionysus invades Thrace, home of Orpheus, and the female followers of Dionysus (the Maenads) tear Orpheus from limb to limb. His head is thrown into the river Hebrus, where it floats to Lesbos, singing the entire time.
The lyre of Orpheus is also thrown into the river, and it too floats to Lesbos, beached near the temple of Apollo. Apollo then convinces Zeus that the instrument should become a constellation. Zeus agrees, and places the lyre of Orpheus between Hercules and Cygnus.

The constellation is small and rather faint, but it is home to the fifth brightest star, Vega. The asterism resembles some multi-legged creature more than it does a lyre, with Vega at the head.
The constellation hasn't the full complement of Bayer stars, and only three stars are brighter than fourth-magnitude. Still, there are some very fine objects to view.

Vega, "Falling Eagle" or "The Harp Star", is only the fifth brightest star, but it dominates the summer skies in the northern hemisphere, with a transit date of 1 July.
About 12,000 years ago Vega served as the Pole Star, and it will again in another 12,000 years. Beta Lyrae, sometimes known as "Sheliak" (Tortoise), is a prototype of a variable star in which a close companion is transferring matter to its gigantic primary. In Beta Lyrae's case, the transference is occurring very rapidly. Eventually the system will become an Algol variable. (See below for its values.)

Double stars in Lyra:
Delta2-Delta1 Lyrae form a wide binary that may be gravitationally bound despite the great distance. The two have a nice colour contrast, orange and blue. Note that delta2 is the primary: 4.3, while delta1 has a visual magnitude of 5.6.
Beta Lyrae is a fixed multiple binary, with a primary of 3.5. AB: 3.5. 8.6; 149º, 46"; AE: 9.9, 318º, 67"; AF: 9.9, 19º, 85".
Epsilon1-Epsilon2 Lyrae: the famous "Double- Double". All four stars are fifth-magnitude. The two principal stars form a very wide binary: PA 173º, separation 208".
Each star is itself a double:
Epsilon1A-Epsilon1B is a slow binary with 1165 year orbit: 5.0, 6.1; PA 350º and separation 2.6".
Epsilon2C-Epsilon2D is about twice as fast, with a period of 585 years: 5.2, 5.5; PA 83.5º, separation 2.3".
Zeta Lyrae is another relatively fixed multiple. The brightest component is D: AD 4.3, 5.9; 150º, 43.7". The other components are fourteen magnitude.
Struve 2470 and Struve 2474 form another fine double-double, that some say is equal to epsilon1,2.
Struve 2470: 6.6, 8.6; 271 degrees, 13.4" and Struve 2474: 6.5, 8.6; 261º, 16.4".
The two binaries are found two and a half degrees NE of gamma Lyrae, which is the brightest star in the region. Or, if you can find iota Lyrae, drop south one and a half degrees. It's a sight well worth the detour!

Variable stars in Lyra:
Alpha Lyrae (Vega) is a delta Scuti type variable, fluctuating from -0.02 to 0.07 every four hours 33.6 minutes.
Beta Lyrae is an EB variable: 3.25 to 4.4 with a period of 12h22m.
RR Lyrae is a prototype for a pulsating type of variable with short periods, usually less than twenty-four hours. RR Lyrae's period is 13h36m, and it changes in magnitude from 7.1 to 8.1.

Deep Sky Objects in Lyra:There are two Messier objects in Lyra: M56 and M57.
M56 (NGC 6729) is a globular cluster, very condensed. It is found eight degrees due south of theta Lyrae.
M57 (NGC 6720) known as the Ring Nebula, is the finest planetary nebula in the skies. The ring itself should be clearly visible in medium scopes, while the fourteen magnitude central star may take a little longer. Burnham gives an excellent discussion on this object.
It is located between beta and gamma Lyrae (slightly closer to beta), and is about 4000 light years distant.

Lyra 4

In time Orpheus took a wife, the young and beautiful Eurydice. But soon after the marriage she was bitten by a serpent and died, where upon she was transported to the Underworld, where all mortals souls went. Orpheus himself entered Hades, playing the lyre as he went. Pluto and all the other ruling spirits were so enchanted by Orpheus' music that they agreed to restore life to Eurydice--but only in one condition--that as Orpheus left Hades he would not look back to see if his wife were following him. As he left Hades, he could not understand why he had not heard footsteps behind him if his wife really were there. Breaking his vow, he looked back. He saw Eurydice, but she was rapidly faded away into the mists of Hades. Now she was lost to him forever, for once reborn, a departed soul cannot be reborn a second time. Utterly sad and lonely, Orpheus spent the rest of his days roaming over the land playing sweet but sad music to himself in memory of his dear wife. So sweet was the music that maidens from far and wide came to him and pleaded that he forget his sorrows and marry one of them. But he would not. Their pride crushed, the young maidens vowed to kill Orpheus since they could not have him for their own. They tore him apart limb by limb and threw his remains and lyre into the river. Zeus knew of these events. Also enchanted by the sweet music of Orpheus, Zeus rewarded the young man by making his music immortal. He raised the lyre into the skies and placed it beside the graceful swan, Cygnus. A small but brilliant constellation, Lyra is crowned with the bright star Vega, also known as the Harp Star.

Chih Nu wove her own wedding dress out of sparkling rays of starlight. They were very happy together. In fact, they were a little too happy and too devoted to each other. Consequently they forgot all about their work. The loom stood still and gathered dusty cobwebs while the royal cattle roamed far and wide across the heavenly meadows. The Sun-King gave them repeated warnings and every time they promised to amend their ways, but soon they lapsed into idleness again. This annoyed the King so much that after several warnings he decided to banish the husband to the other side of the Milky Way again so that he could tend the cattle there. When he had dispatched Ch'ien Niu across the one and only ford, T'ien-tsin, the King had both sides closed by barriers and a guard posted with instructions that neither of them were allowed to pass along this route. Chih Nu pleaded with her father but to no avail. Finally she appealed to the magpies who had pity on the couple. The magpies decided that once a year on the seventh day of the seventh month they would help the parted lovers. On that day all the magpies in China would fly to the Milky Way and make a bridge across it with outspread wings across which the lovers would rush into each other's arms and spend the rest of the day together. On that day a soft rain began to fall in the morning, which were their tears of happiness. But at nightfall the soft rain became a downpour, caused by the tears of having to part again for a year. Having done their duty the magpies would fly away again. When on the following day people saw the magpies in the fields once more they would rejoice and say: "Yes, look, the lovers have been together. See how the feathers on the birds are all worn down where their feet have trampled." If the feathers weren't trampled down the people would be sad and used to say that bad weather had apparently prevented the birds from building the bridge across the Milky Way. It is also said the children are told to throw stones at any magpies if the saw them in the fields on the seventh day of the seventh month, because those selfish birds were negligent of their duty.

The constellation is named for a musical instrument used by the ancient Greeks. It is very similar to a harp, but only has 3 to 10 strings.

Hermes, Messenger of the Gods, one day came upon an empty tortoise shell on the beach and out of it fashioned a small harp like instrument, the lyre. When in the right hands the instrument produced the most beautiful music ever heard by either gods or mortals. Hermes traded his invention with the Sun-god Apollo. Later, Apollo presented the lyre to his son Orpheus. So gifted was Orpheus at playing the lyre that neither mortals, beasts, nor the gods themselves could turn away when he played. It is said that on hearing Orpheus play, Pluto, Lord of the Underworld, wept tears of iron.

The Sumerians and Babylonians saw Lyra not as a harp but a vulture. This is suggested by early records of the constellation as a harp being carried by a vulture. So instead of being the Harp star it may once have been the Vulture Star.

The ancient peoples of Britain called Lyra "the Harp of King Arthur."

The Chinese have a story about a weaving Princess and her cowherd lover. Chih Nu (Vega) was the daughter of the Sun-God. She was a most clever and deft weaving and spinning artist and could make the most exquisite tapestries. One sunny summer day she happened to look out of the palace window and saw her father's herdsman driving the flock of the King along the banks of the Milky Way. As so often happens in love stories, their glances met and both knew that this was love at first sight. The King who had been worried about his daughter's future was delighted when he heard about their romance, especially as the herdsman Ch'ien Niu (Altair) was a very conscientious worker who had always looked after the royal flock with the utmost care.

Lyra 3

Alpha Lyrae

Distance (Light Years)
25.3± 0.1
Visual Magnitude
Color (B-V)
Names For This StarAnother name for this star is Wega. These names probably derive from the Arabic name, Al Nasr al Waki, "The Eagle with Partially Closed Wings." This was the name assigned to a group of three stars in Lyra, including Vega. Vega or Wega derives from Waki.
Other names for Vega are Fidis, Fides or Fidicula, which are other Latin words for a harp or a lyre. Vega is also known as The Harp Star.
Description of the StarVega is a hot, white A0Va main sequence star having about 50 times the luminosity of the sun and 2.6 times the sun's diameter. The spectral type implies an effective temperature of 9900 K and 3.3 times the mass of the sun.
Vega is short period pulsating type of Delta Scuti type with a period of 4.6 hours. See Caph.
Vega is a young star relatively near us, where planets appear to be forming. There are also images of dust discs around Vega and other stars.

Lyra 2

The Lyre

The Brighter Stars of Lyra
The Story
The Lyre of OrpheusThe Lyre is the Lyre of Orpheus, but it was invented by Hermes, the Messenger God. Hermes happened upon an empty tortoise shell, and turning the shell around in his hands, he idly thumped it. The resonant echoes of the shell gave him the idea of tying strings across the shell. He found the strings made beautiful sounds, and so the Lyre was created.
The Deal With ApolloHermes gave the Lyre to the god Apollo. Some say that Hermes traded the Lyre for a magical staff that brings wealth and prosperity. Others say that Hermes used the Lyre to appease the anger of Apollo, when Hermes was caught making off with Apollo's cattle.
Orpheus Ends Up With the LyreApollo passed the Lyre on to his Orpheus, who sailed with Jason and the Argonauts and was the most accomplished musician of the age. The music of Orpheus could charm people, even angry people and wild beasts. Orpheus with his Lyre could charm even rocks and streams. It is said that the oak trees growing along the coast of Thrace migrated there to better hear the songs of Orpheus.
Orpheus' Sad EndOrpheus lost his wife Euridyce to death, and failed in his attempt to win her back from the God of the Underworld. Orpheus himself died after being set upon by a mob. One story has it that it was the intoxicated followers of Dionysius who tore the musician limb from limb. In another story, it is a mob of women who stabbed Orpheus to death. They were angry because the musician, still in love with his long dead wife, had spurned their affections. After the mob killed Orpheus, they took his Lyre and threw it in a river.
The Lyre Ends Up in the StarsZeus sent a vulture to retrieve the Lyre, which he set into the stars. Others say that it was the Nine Muses who carried the Lyre into heaven.

Lyra 1

Here are some of Lyra's brighter stars:
α Lyr (Vega): with an apparent brightness of 0.03m this is the second brightest star of the northern hemisphere (after Arcturus) and the fifth brightest star in all; its spectral class is A0 V and it lies at a distance of only 25.3 ly.
β Lyr (Sheliak): a group of eclipsing binaries is named after this variable star (3.45m, spectral class B8 II), the Beta-Lyrae-stars.
γ Lyr (Sulafat): the main star of this multiple star system is of magnitude 3.24m and spectral class B9 III
δ Lyr: a double star consisting of a blue-white star of mag. 6m and a semi-regular red giant varying between 4m and 5m.
ε Lyr: a well-known quadruple star, also called "the Double Double" because each of the two brighter components is itself a close double.
ζ Lyr: another double star which can be split using binoculars.
RR Lyr: lent its name to a class of pulsating variable rated r superstars the RR Lyrae-stars.

For millennia, Lyra was shown as a vulture or an eagle, and thus the bird was frequently shown with a lyre enclosed in its wings, though often in its beak. The constellation is therefore frequently referred to as Aquila Cadens or vultur cadens, falling eagle or falling vulture.
When Orpheus was struck by grief at the death of his wife, he vowed never to fall in love again. He was killed by a group of Thracian women upset with his rejection, they tore him limb from limb and sent his head to the island of Lesbos. After that his lyre was thrown into the river. Zeus sent an eagle to retrive the lyre, and ordered both of them to be placed in the sky.
In the film K-PAX the constellation of Lyra is the location of the planet K-PAX which is an inhabited world which orbits twin stars and has seven moons.
In Australian Aboriginal Astronomy, Lyra is known by the Boorong people in Victoria as the Malleefowl constellation.
Lyra was known as Urcuchillay by the Incas and was worshipped as an animal deity.


Localisation de la constellation

La constellation se reconnaît directement à sa forme : Véga est une étoile très brillante, qui se reconnaît par son association avec les deux étoiles plus faibles (mag 3) β et γ Lyr, l'ensemble évoquant très nettement un club de golf. Quand les conditions de visibilité sont meilleures, Véga se trouve à la pointe d'un petit "V" qui rappelle son nom.
A plus longue distance, la constellation est sur l'alignement qui part de la Grande Ourse, suivant la diagonale SO-NE de la "casserole". Cet alignement passe par le cœur du Dragon et par sa tête, pour venir toucher Véga, puis plus loin Altaïr de l'Aigle.
Véga est l'un des sommets du grand triangle d'été, facilement repérable par lui-même.

La Lyre est une constellation ancienne. Les civilisations antiques en Moyen-Orient et en Inde y voyaient un vautour. Les astronomes grecs y voyaient une lyre (ou plutôt une « kithara ») et les cartes du ciel les plus vieilles la représentent généralement tenue dans les griffes d'un vautour.
Sous la forme d'un vautour, cette constellation s'est raccrochée à la légende d'Hercule qui, pour son 6e travail, tua les oiseaux du lac Stymphale. La constellation est d'ailleurs proche du Cygne et de l'Aigle.
La lyre représenterait pour sa part l'instrument de musique d'Orphée.

Lepus 6

The hare
أرنبAlpha Leporis (α Lep / α Leporis) is the brightest star in the constellation Lepus. It also has the traditional name Arneb (hare in Arabic).
Alpha Leporis is an older, dying star that may have already passed through a supergiant phase and is now contracting and heating up in the latter phases of stellar evolution, or perhaps is still expanding into the supergiant phase. With a mass of likely less than 10 times that of the Sun, it will likely end its life as a hot white dwarf, although if it is at the heavier end of its estimated mass it may end in a spectacular stellar explosion known as a supernova.

The camels quenching their thirst

Beta Leporis (β Lep / β Leporis) is a star in the constellation Lepus and is also known as Nihal. Beta Leporis has apparent magnitude +2.81 and is 159.2 light years from Earth. It is a yellow supergiant of spectral class G5II with 150 times the luminosity of the Sun.
Coordinates (equinox J2000)
Right ascension: 5h28m14s
Declination: −20°45'32"

Epsilon Leporis (ε Lep / ε Lep) is a Class K5III, third-magnitude star in the constellation Lepus. It is occasionally called Sasin or Sasanka, meaning "Marked With the Hare", a name given to both the Moon and the constellation Lepus by the ancient Hindus.
This star is an orange giant, located about 225 light-years from Earth.

Mu Leporis (μ Lep / μ Lep) is a Class B9III, third-magnitude star in the constellation Lepus. It's nearly obscure proper name Neshmet is the original Egyptian name for the Boat of Osiris or Asar, which was imagined by the Egyptians among the stars of Lepus.
This star is a blue giant, located about 185 light-years from Earth.

Zeta Leporis (ζ Lep / ζ Leporis) white main sequence star approximately 70 light-years away in the constellation of Lepus. The star is suspected of being a spectroscopic binary star system, but this is yet to be confirmed. As of 2001, an asteroid belt was confirmed to orbit around the star.

Gamma Leporis (γ Lep / γ Leporis) is a multiple star system which is located at a distance of about 29 light-years from Earth and consists of 2 or 3 stars: Gamma Leporis A, Gamma Leporis B and possibly Gamma Leporis C.
Gamma Leporis lies in the south central part of the constellation Lepus, southeast of Beta Leporis and southwest of Delta Leporis. The system is a member of the Sirius group. Based upon its stellar characteristics and distance from Earth, Gamma Leporis is considered a high-priority target for NASA's Terrestrial Planet Finder mission.

Lepus 5

"The Hare", is an ancient constellation found under the feet of Orion, the Hunter. No one seems to know just which culture first saw the constellation as an animal; the Arabs saw it as the "throne of the central one" (i.e. Orion).
Lepus, The Hare is not to be confused with Lupus, The Wolf, which is a spring constellation.
Lepus is often ignored, as Orion is such a dominating constellation. Yet Lepus contains a number of interesting objects. Its Bayer stars are generally third and fourth magnitude.

Double stars:
Beta Leporis is a close binary with faint companion: 2.8, 11; PA 330 degrees, separation 2.5".
Gamma Leporis is a wide binary with slight colour contrast, yellow and orange (although observers vary): 3.7, 6.3; PA 350, separation 96.3".
Kappa Leporis (Struve 661) is a fixed system: 4.5, 7.4; PA 358 degrees, separation 2.6".
h3750 is a fixed binary: 4.7, 8.5; PA 282 degrees, separation 4.2".
h3752 is a fine multiple in the same field as M79.
AB: 5.5, 6.5; PA 97 degrees, separation 3.1". AC: 9; PA 106 degrees, separation 59".
h3780 is a noted multiple system which also goes under the name NGC 2017.
AB: 6.4, 7.9; PA 146 degrees, separation 0.8" AC: 8.5; PA 136 degrees, separation 89.2". AE: 8.4; PA 7, separation 76.1". AF: 8.1; PA 299, separation 28.8". AG: 9.5; PA 49, separation 59.8".

Variable stars:
Mu Leporis is an alpha CV type variable: 2.97 to 3.41 about every two days.
Rho Leporis is an alpha Cygni type variable: 3.83 - 3.90.
R Leporis is a long-period (Mira) variable that ranges from about 6 to about 11.5 every 427.07 days. However sources vary over this figure, and you will find quoted a period ranging from 427 to 440 days. In 2000 the maximum may occur in the last week of December, depending of course on the star's current period.
The star glows with an unusually intense red; it goes by the name of Hind's Crimson Star since John Russell Hind (in 1845) wrote that it resembled "a blood-drop on the background of the sky". Although, unfortunately, as the star brightens it loses much some of its intense colour.
The star is 3.5º NW of mu Leporis. Burnham (p.1094) has a finder's chart. (The star less than two degrees south of R Lep is the close binary b314.)

Deep Sky Objects:
Lepus has one Messier and a tiny star cluster which is actually the half dozen stars which go to make up the multiple h3780.
M79 (NGC 1904) is a small globular cluster about 3.5 degrees SSW of beta Leporis. In the same field, half a degree to the SSW of this cluster, is h3752 (see above).
NGC 2017 is a group of a half dozen stars, all gravitationally bound (h3780, see above). The "cluster" is found seven arc minutes due east of alpha Leporis.

Lepus 5

"The Hare", is an ancient constellation found under the feet of Orion, the Hunter. No one seems to know just which culture first saw the constellation as an animal; the Arabs saw it as the "throne of the central one" (i.e. Orion).
Lepus, The Hare is not to be confused with Lupus, The Wolf, which is a spring constellation.
Lepus is often ignored, as Orion is such a dominating constellation. Yet Lepus contains a number of interesting objects. Its Bayer stars are generally third and fourth magnitude.

Double stars:
Beta Leporis is a close binary with faint companion: 2.8, 11; PA 330 degrees, separation 2.5".
Gamma Leporis is a wide binary with slight colour contrast, yellow and orange (although observers vary): 3.7, 6.3; PA 350, separation 96.3".
Kappa Leporis (Struve 661) is a fixed system: 4.5, 7.4; PA 358 degrees, separation 2.6".
h3750 is a fixed binary: 4.7, 8.5; PA 282 degrees, separation 4.2".
h3752 is a fine multiple in the same field as M79.
AB: 5.5, 6.5; PA 97 degrees, separation 3.1". AC: 9; PA 106 degrees, separation 59".
h3780 is a noted multiple system which also goes under the name NGC 2017.
AB: 6.4, 7.9; PA 146 degrees, separation 0.8" AC: 8.5; PA 136 degrees, separation 89.2". AE: 8.4; PA 7, separation 76.1". AF: 8.1; PA 299, separation 28.8". AG: 9.5; PA 49, separation 59.8".

Variable stars:
Mu Leporis is an alpha CV type variable: 2.97 to 3.41 about every two days.
Rho Leporis is an alpha Cygni type variable: 3.83 - 3.90.
R Leporis is a long-period (Mira) variable that ranges from about 6 to about 11.5 every 427.07 days. However sources vary over this figure, and you will find quoted a period ranging from 427 to 440 days. In 2000 the maximum may occur in the last week of December, depending of course on the star's current period.
The star glows with an unusually intense red; it goes by the name of Hind's Crimson Star since John Russell Hind (in 1845) wrote that it resembled "a blood-drop on the background of the sky". Although, unfortunately, as the star brightens it loses much some of its intense colour.
The star is 3.5º NW of mu Leporis. Burnham (p.1094) has a finder's chart. (The star less than two degrees south of R Lep is the close binary b314.)

Deep Sky Objects:
Lepus has one Messier and a tiny star cluster which is actually the half dozen stars which go to make up the multiple h3780.
M79 (NGC 1904) is a small globular cluster about 3.5 degrees SSW of beta Leporis. In the same field, half a degree to the SSW of this cluster, is h3752 (see above).
NGC 2017 is a group of a half dozen stars, all gravitationally bound (h3780, see above). The "cluster" is found seven arc minutes due east of alpha Leporis.

Lepus 4

Lepus is an ancient constellation found under the feet of Orion, the Hunter. The creature is associated with the Moon in mythology. Some say that the dark regions on the surface of the Moon are a rabbit, originally Lepus. The rabbit was the favorite prey of Orion and his hunting dogs.

No one seems to know just which culture first saw the constellation as an animal; the Arabs saw it as the "throne of the central one" (Orion).

Lepus 3

Alpha Leporis

Distance (Light Years)
1280 ± 360
Visual Magnitude
Color (B-V)
Names For This StarThe name for this star derives from the Arabian name for the constellation of Lepus: Al Arnab.
Description of the StarArneb is an F0Ib supergiant star. The Visual Magnitude and distance imply a luminosity about 10,000 times that of the sun.

Beta Leporis

Distance (Light Years)
159.2 ± 6.6
Visual Magnitude
Color (B-V)
Names For This StarNihal (Nibal) would seem to derive from the name that was formerly applied by the Arabs to the four brightest stars of Lepus - Al Nihal, "The Drinking Camels." The stars were seen as camels drinking from the river of the near-by Milky Way.
Description of the StarNihal is a yellow G5II bright giant star having a luminosity about 150 times that of the sun.
According to Burnham, Nihal has a dim companion of perhaps 11th magnitude at a separation of about 2.5 arc seconds, corresponding to a projected distance of 122 AU that is, about 3 times the distance from the sun to planet Pluto. The period of the orbit of the companion appears to be several hundred years.

Lepus 2

The Hare

The Brighter Stars of Lepus
The Story
The Speedy HareThe Hare was set into the sky by the Messenger God, Hermes, to honor the hare's swiftness. In the winter sky the hare is seen right by the feet of the Great Hunter Orion. The rabbit is quite and prone, but ready to flee.
Lepus and the Easter Bunny According to Staal, the legend of the Easter Bunny may also be connected with this constellation. According to the story, there was at one time a bird, which was changed into the hare by the Anglo-Saxon Goddess of Spring, whose name was Ostara. or Eostre. The creature lost its power to fly, but Ostara compensated this loss by giving the hare great speed.
Once a year the hare is allowed to lay eggs again, which is why in the springtime, we hunt for the eggs of the Easter Bunny.

Lepus 1

Hermes placed the hare in the sky because of its swiftness, Eratosthenes tells us. Both Eratosthenes and Hyginus referred to the remarkable fertility of hares, as attested to by Aristotle in his Historia Animalium: ‘Hares breed and bear at all seasons, superfoetate (i.e. conceive again) during pregnancy and bear young every month. They do not give birth to their young all at once, but bring them forth at intervals.’

The celestial hare makes an interesting tableau with Orion and his dogs. Aratus wrote that the Dog (Canis Major) pursues the hare in an unending race: ‘Close behind he rises and as he sets he eyes the setting hare.’ But judging by its position in the sky, the hare seems more to be crouched in hiding beneath the hunter’s feet.
Hyginus tells us the following moral tale about the hare. At one time there were no hares on the island of Leros, until one man brought in a pregnant female. Soon, everyone began to raise hares and before long the island was swarming with them. They overran the fields and destroyed the crops, reducing the population to starvation. By a concerted effort, the inhabitants drove the hares out of their island. They put the image of the hare among the stars as a reminder that one can easily end up with too much of a good thing.
The constellation’s brightest star, third-magnitude Alpha Leporis, is called Arneb, from the Arabic al-arnab meaning ‘the hare’.


Localisation de la constellation
Le Lièvre se situe immédiatement au Sud de la constellation d'Orion, le grand chasseur, et à l'Ouest de Sirius, le grand chien. Sa localisation est donc très facile. Il ne doit sa survie dans un tel entourage qu'à sa relative discrétion, ses étoiles étant relativement plus faibles (mag 3) que celles de ses glorieux voisins.
Ses deux étoiles les plus brillantes sont situées dans l'axe de Sirius et β CMa, qui forme sa patte avant, à ~10° plus à l'Ouest. β Lep est au Sud, et α Lep au nord; ces deux étoiles pointent à leur tour vers κ Ori (Saiph), ~10° plus au Nord.
Forme de la constellation
La constellation n'a pas de forme très convainquante.
Côté Ouest, la tête du Lièvre est formée par ε Lep (5° OSO de β Lep), qui marque le bout du nez, μ Lep (5° ONO de α Lep), qui marque la base des oreilles, dont l'extrêmité se devine par beau temps avec la paire λ Lep (côté Est) et κ Lep (Ouest), situées à mi-chemin de Rigel.
Côté Est, le corps du Lièvre dessine une forme ovoïde, avec (dans le sens des aiguilles d'une montre) α et β Lep, au Sud γ et δ, pointant vers θ sur l'arc Nord qui se referme par η et ζ Lep.

Le Lièvre est entouré de Orion au nord, et du Grand Chien à l'Est, qui permettent de le repérer facilement.
Quand la visibilité est bonne, la tête du Lièvre permet de repérer le grand ménadre Est de Éridan. L'alignement Nord de la tête formé par α et μ Lep se prolonge par l'alignement de ι (après ~10°) et γ (encore ~10°) de Éridan. L'alignement formé par α et le bout du nez μ Lep pointe au SO après ~10° vers la paire ν1 et ν2 Eri, et 5° plus loin vers ν3 et ν4 Eri.
Côté Sud, la Colombe est marquée par la première paire d'étoiles brillantes, à ~12° plein Sud de la tête du Lièvre.

Hydra 6

Alphard (α Hya / α Hydrae / Alpha Hydrae) is the brightest star in the constellation Hydra, marking the heart of the snake.
Alphard is an orange giant star. The name Alphard is from the Arabic فردالفرد (Al Fard), "the solitary one."
Precise radial velocity measurements [1] have shown variations in the stellar radial velocities and spectral line profiles. The oscillations are multi-periodic with periods from several hours up to several days. The short-term oscillations were assumed to be a result of stellar pulsations, similar to the solar ones. A correlation between the variations in the asymmetry of the spectral line profile and the radial velocity has also been found. The multi-periodic oscillations make HD 81797 (Alphard) an object of interest for asteroseismologic investigations.

Gamma Hydrae (γ Hya / γ Hydrae) is a Class G8, third-magnitude star in the constellation Hydra. It is sometimes called Cauda Hydrae or Dhanab al Shuja, meaning "Hydra's Tail" or "the Snake's Tail".

Zeta Hydrae (ζ Hya / ζ Hydrae) is a Class G9, third-magnitude star in the constellation Hydra. As the brightest star of the Hydra's head, it is occasionally called by the proper name Hydrobius, meaning "Water-dweller", in Greek.

Nu Hydrae (ν Hya / ν Hydrae) is a Class K2, third-magnitude star in the constellation Hydra. It is sometimes called by the proper names Sherasiph and Pleura, each name referring to the "ribs" or "side" (of Hydra) in Arabic and Greek, respectively.

Pi Hydrae (π Hya / π Hydrae) is a Class K2, third-magnitude star in the constellation Hydra. It is sometimes called by the Sanskrit proper name Sataghni. Some sources also name it Markeb.

Epsilon Hydrae (ε Hya / ε Hydrae) is a Class G5, third-magnitude star in the constellation Hydra. The Vedic Sanskrit name Ashlesha (Azleṣa) [1], meaning "The Embracing One", is sometimes applied to this star.
Epsilon Hydrae is a binary star with components of magnitudes 3.3 and 6.8, separated by 2.7 arcseconds. This stellar system is located about 135 light-years from Earth.
Delta Hydrae (δ Hya / δ Hydrae) is a Class A1, fourth-magnitude star in the constellation Hydra. It is sometimes called Mautinah, meaning "Circlet of Pearls" in Arabic, which refers to an asterism imagined by ancient Arabs among the semicircle of stars in the Hydra's head.
Delta Hydrae is a binary double star, located about 180 light-years from Earth.
Sigma Hydrae (σ Hya / σ Hydrae) is a star in the constellation Hydra. It also has the traditional name Minchir (or Michar or al Minchar al Shuja (Arabic for "Nose of the Hydra").
The Bayer designation Tau Hydrae (τ Hya / τ Hydrae) is shared by two star systems, τ¹ Hydrae and τ² Hydrae, in the constellation Hydra. The two stars are separated by 1.74° on the sky. Tau Hydrae also has the traditional name Ukdah, from the Arabic عقدة uqdah meaning the Knot.

Hydra 5

Double stars in Hydra:
Beta Hydrae is a pair of nearly equal stars (4.5, 5) at PA 8º and a separation of 0.9".
Epsilon Hydrae is a multiple binary; four stars can be seen and another has been calculated to exist.
Components A and B form a rapid binary with a period of 15.05 years; its orbit is nearly circular. Presently (late February 1996) the companion star has a PA of 166º and separation 0.26".
Component C is much easier to resolve, with a period of 990 years. At present it can be found at a PA of 298.5º and separation 2.7".
Chi1 Hydrae is a binary of two similar stars (5.8, 5.8) with an even more rapid orbit. Its period of 7.4 years means an exceedingly difficult binary to resolve. If you've a large enough telescope, you'll find the companion at these values in late February 1996: PA 31º and separation 0.046".
Sigma 1474 is a fixed binary forming a wonderful triple. AB: 6.8, 7.9; 24º and separation 70"; C: 6.9, 23º, 76" separation.
To find the binary, locate nu Hydrae then move one degree northwest. (Just north half a degree is the nearly attractive Sigma 1473.)

Variable stars in Hydra:
R Hydrae ranges from a visual magnitude of a fairly bright 3.5 to a faint 10.9 every 388.87 days. However this star has shown a decrease in its period. (In 1920 it had a 404 day period.) In 2000, based on its current period of 388 days, the maximum should be attained during the first week of August.
This star is one of the earliest variables to be catalogued, having been discovered in 1704. Only Mira (omicron Ceti), beta Persei, and chi Cygni predate R Hydrae.
Burnham gives a finder's chart. Note that the brightest star in the region, SS Hydrae, is also a variable, so don't base R Hydrae's visual magnitude on this star.
T Hydrae has a shorter period, 298.7 days, and a range of 6.7-13.5. To find T Hydrae, star hop westward from Alphard. First, due west of alpha Hydrae you find 24 Hydrae, then 20 and 19 (which is the brighter of the two). Now just about the same distance that you've taken to get to 19 Hydrae you'll find T Hydrae, due south of 17 Hydrae one and a half degrees.
This star, 17 Hydrae, is the brightest star in the region, and a visual binary as well (7, 7; 359º, 4.3"). The star is useful to determine the visual magnitude of T Hydrae to the south.
In 2000 T Hydrae should attain its maximum brightness in mid October.

Deep Sky Objects in Hydra:
Hydra has three Messier objects: M48, M68, and M83.
M48 (NGC 2548). Messier actually gave the wrong location for this star cluster, putting it four degrees north of the current position. But by his description this seems to be the right object.
Not terribly spectacular, this is a group of fifty stars, the brightest of which is about 8.8 visual magnitude. The cluster is thought to be about 1700 light years away, and is easily seen in binoculars or small telescope.
M68 (NGC 4590) is a much richer globular cluster of over a hundred thousand stars, resolved in medium-sized telescopes.
The cluster lies in a desolate part of the sky. Locate gamma Hydrae then move west to beta Corvi. Now drop down three degrees to the brightest star in this region, a fifth-magnitude star (this is the binary B230: 5.5, 12; 170 degrees, separation 1.3"). M68 is about a half degree to the northeast.
M83 (NGC 5236) is a spiral galaxy sitting on the Hydra-Centaurus border farther to the east, nearly twenty degrees south of Spica (alpha Virginis).
While Burnham says this is considered one of the brightest galaxies with a visual magnitude of about 8, other references give it only a 10. And since it is very diffuse, it may be difficult for those living in northern latitudes.
NGC 5694 is an extremely compact globular star cluster, thought to be in the region of 100,000 light years away.
The cluster sits just east of the mid-way point between pi Hydrae and sigma Librae, at the border with Hydra. From pi Hydrae move east until you encounter a group of five magnitude stars lined up roughly north-south. These are 54, 55, 56, and 57 Hydrae. NGC 5694 lies one degree west of 57 Hydrae.
NGC 3242 clearly deserves to be a Messier object. Small but bright, at a visual magnitude of 8.6, this planetary nebula is often called The Ghost of Jupiter because of its slight resemblance (?) to that planet. Also at times called The Eye Nebula, perhaps a closer description.
The nebula gives off a soft bluish colour, sometimes described as a "glow", that is clearly visible even in small scopes. The central star may be difficult to resolve: this is an 11.4m star, a blue dwarf considered to be as hot as 60,000 kelvin.
The nebula is one of the easiest to find. Just locate mu Hydrae then move south two degrees.
Trying to resolve the inner ring could prove difficult. Large telescopes should show the object as resembling an eye, with the central star the pupil. The greenish-blue colour adds to this intriguing sight.

Hydra 4

Like a number of other constellations, the Hydra concerns the story of Heracles' labours. This time it is the Second Labour of Heracles.
Having killed the Nemean Lion, and wrapping the protective pelt around himself, Heracles set off to find the Hydra. This was a gigantic dog-like beast with many heads. Some say it had seven, others as many as fifty. Euripides, with characteristic exaggeration, gave it ten thousand heads.
Seven is usually the accepted number, possibly because of the seven rivers in this part of the Peloponnesian peninsula, tributaries of the river Amymone.
At any rate, one of these heads was immortal, which meant the beast was immortal. Its breath was deadly and if one even smelled its tracks, he would die.
With the help of Athene, Heracles locates the monster's lair and soon he is in a life and death struggle with the beast. Heracles slices off one of the monster's heads, only to see a couple more grow in its place.
Heracles calls out to his chariotter Iolaus for help. Iolaus sets the grove on fire and then begins cauterizing the bleeding stumps. With the blood flow stopped the Hydra's heads cease to multiply.
Finally Heracles cuts off the immortal head and - as it is still furiously hissing away - he promptly buries it under a huge rock. He cuts up the rest of the Hydra's body and dips all his arrows in the dead monster's gall. The slightest scratch from one of these arrows would bring instant death.
While one might be tempted to say "well done", Eurystheus (who had assigned these labours to Heracles) was not satisfied. Heracles had cheated, he said, since he had needed Iolaus' assistance.
One might wonder just why Heracles had been forced to do all these labours. Before either he or his twin were born, Hera decided that Eurystheus rather than Heracles should become the king of Mycenae. So she hastened his birth; Eurystheus was born two months premature. And Heracles, being the younger of the two, became subservient to Eurystheus.
Thus born premature, this king of Mycenae was weakly and timorous. He commanded Heracles to perform twelve labours in twelve years in order to keep him away from his own kingdom, afraid Heracles would take his throne. Eventually he would be killed by either Heracles' son (Hyllus) or by his charioteer, Iolaus.
As a constellation Hydra sinuously winds down from the northern hemisphere, bordering Cancer, to as far in the southern hemisphere as Centaurus, stretching out to around one hundred degrees in the process. At one point its body is actually cut off by another constellation (the southwestern tip of Crater).
Although the constellation is best seen in March and April, its brightest star, alpha Hydrae, transits on 12 February. Slowly over the next few months the Hydra then slithers over the skies earlier and earlier.
To find Hydra, locate Regulus (alpha Leonis). Now drop straight down twenty degrees, passing through the uninspiring constellation of Sextans. The bright star to the west is Alphard (alpha Hydrae).
You've just found the "heart" of the Hydra. To find its head, look for the compact stars to the northwest. It is easiest to do this with the naked eye, or with binoculars. These stars are not quite as far north as Regulus.
The tail of the monster stretches far to the east, even past Spica (alpha Virginis). You'll have to wait until the small hours of the morning to see these stars, or until later in the spring when they appear at a more reasonable hour.
There are a number of interesting deep sky objects, including two Messier objects, and several very nice double stars. All in all, Hydra's stars are of average brilliance, except for Alphard (alpha Hydrae).
Alphard is a bright giant, about 25 times the Sun's diameter. Its distance is 89 light years, and it has a luminosity of 95 Suns.
The Arabs called the star "Al Fard al Shuja" (The Solitary One in the Serpent) while later on Tycho Brahe named it "Cor Hydrae" (The Hydra's Heart).
Beta Hydrae is the southern-most star of any importance. Quite dim for its name, the star is a visual binary (see below).

Hydra 3

On day the Sun-god, Apollo, sent his pet raven down to Earth to bring the thirsty god a cup of fresh water. Apollo's sacred raven was not a very dependable bird. On arriving at the spring the raven saw that a fig tree was just beginning to bear fruit. "What matter if I wait only a few days until the fruit ripens?" the raven asked itself. And it waited. When the fruit ripened the raven then stayed several more days eating the fruit until it was all gone. He then filled the cup with fresh spring water but realized that his master would be angry for the long delay. Then he noticed a water-serpent nearby and grasped it in his claws. So with cup in mouth and serpent dangling from his claws, the raven flew up to Heaven. He explained to Apollo that the serpent had attacked him and that is what caused the delay. Apollo was not taken in by the lie. And he was so angry with the bird that he flung him, cup and serpent out of Heaven. Today we see them together in the sky as Crater, the Cup, and Corvus, the Raven, perched on the serpent's back. This myth gave rise to two alternate manes for Corvus as a constellation: Avis Ficarius, or "the Fig Bird," and Emansor, or "One Who Lingers Too Long."

The swamps of Lerna was home of the Hydra, an enormous water snake with nine heads (one of which was immortal), and with breath that would kill on contact. With the help of Athene, Hercules located the monster's lair, and the ensuing struggle was a standoff. When one head was sliced off, another appeared in its place. Hercules solved this problem by using a torch to cauterize each stump after he cut off that head. Then at Hydra's plea, a giant crab emerged from the swamp and bit into Hercules' foot. Hercules promptly killed the crab and then cut off the Hydra's immortal head and placed under a huge stone where it could do no more harm. He then dipped his arrows in the Hydra's blood. The slightest scratch from one of these arrows would bring instant death to his enemies.

Another story about Hydra describes him not as a dragon-monster but as a water serpent.

Hydra 2

The Watersnake (female)

The Brighter Stars of Hydra

The Story
Hercules' Labors

The monstrous Hydra figures in the second Labor of Hercules.
No Problem Losing Its Head...

The Hydra was a multiheaded snakelike monster that lived in the marshes near the town of Lerna. The Hydra was the result of a mating between the monster Typhon and the Echidna, which was a creature that was half snake and half woman. The Hydra was difficult to kill, because when one head was cut off, two more heads grew back out of the stump of the old one.
Slaying the Hydra

Hercules was able to slay the monster with the aid of his charioteer Iolaus, who burned the stumps with a torch as Hercules cut off the heads of the monster. It was said that one of the heads of the monster was immortal. So after cutting off that head, Hercules buried it under a large rock.
The Poison Arrows

After slaying the monster, Hercules cut open its body and soaked the heads of this arrows in the poisonous blood of the monster's body.

Alpha Hydrae

Distance (Light Years) 177.3 ± 7.5
Visual Magnitude 1.99
Color (B-V) 1.44

Names For This Star

Other names for this star are Alfard, Alphart, Kalbelaphard, or Cor Hydrae. The last of these names is Latin meaning "The Hydra's Heart." This was the designation of this star first introduced by the great sixteenth century astronomer Tycho Brahe. The other names for this star derive from the Arabic phrase Al Fard al Shuja, meaning "The Solitary One in the Serpent."
Description of the Star

Alphard is an orange K3II-III subgiant or giant.

Hydra 1

Hydra is the largest of the 88 constellations, winding a quarter of the way around the sky. Its head is south of the constellation Cancer, the Crab, while the tip of its tail lies between Libra, the Scales, and Centaurus, the Centaur. Yet for all its size there is nothing prominent about Hydra. Its only star of note is second-magnitude Alphard, a name that comes from the Arabic al-fard appropriately meaning ‘the solitary one’.
The water-snake features in two legends. First, and most familiar, the Hydra was the creature that Heracles fought and killed as the second of his famous labours. The Hydra was a multi-headed creature, the offspring of the monster Typhon and the half-woman, half-serpent called Echidna. Hydra was thus the brother of the dragon that guarded the golden apples, commemorated in the constellation Draco. Hydra reputedly had nine heads, the middle one of which was immortal. (In the sky, though, it is shown with one head only – perhaps this is the immortal one.)
Hydra lived in a swamp near the town of Lerna, from where it sallied forth over the surrounding plain, eating cattle and ravaging the countryside. Its breath and even the smell of its tracks were said to be so poisonous that anyone who breathed them died in agony.
Heracles rode up to the Hydra’s lair in his chariot and fired flaming arrows into the swamp to force the creature into the open, where he grappled with it. The Hydra wrapped itself around one of his legs; Heracles smashed at its heads with his club but no sooner had one head been destroyed than two grew in its place. To add to Heracles’s worries, a huge crab scuttled out of the swamp and attacked his other foot, but Heracles stamped on the crab and crushed it. The crab is commemorated in the constellation Cancer.
Heracles called for help to his charioteer Iolaus who burned the stump of each head as soon as it was struck off to prevent others growing in its place. Finally Heracles cut off the immortal head of the Hydra and buried it under a heavy rock by the roadside. He slit open the body of the Hydra and dipped his arrows in its poisonous gall.

A second legend associates the water-snake with the constellations of the Crow (Corvus) and the Cup (Crater) that lie on its back. In this story, the crow was sent by Apollo to fetch water in the bowl, but loitered to eat figs from a tree. When the crow eventually returned to Apollo it blamed the water-snake for blocking the spring. But Apollo knew that the crow was lying, and punished him by placing him in the sky, where the water-snake eternally prevents him from drinking out of the bowl.


The constellation Hydra resembles a twisting snake, and features as such in some Greek myths. In Greek mythology, a crow serves Apollo. It is sent to fetch water, but it rests lazily on the journey, and after finally obtaining the water in a cup, takes back a water snake as well, as an excuse. According to the myth, Apollo saw through the fraud, and angrily cast the crow, cup, and snake, into the sky. The origin of this story is likely to be the juxtaposition of this constellation with those of Crater, and Corvus, in the area of the sky known as the Sea.
The Hydra was also considered to be the Lernaean Hydra (as defeated by Heracles for one of his Twelve Labours) by the Greeks. Its position in the sky (below the ecliptic), together with the constellation Cancer (which lies near its head) may be the origin of parts of the myth.

Hercules 6

Beta Herculis (Beta Her / β Herculis / β Her), which also has the name Kornephoros, is the brightest star in the constellation of Hercules. It has an apparent visual magnitude which varies between 2.76 and 2.81.
Although β Herculis appears to the naked eye to be a single star, W. W. Campbell discovered in July 1899 from spectroscopic measurements that its radial velocity towards the Sun varies, and concluded that it is a binary system of two stars. An orbit for the binary was computed in 1908 from additional spectroscopic measurements.
At Palomar Observatory, Antoine Labeyrie and others used speckle interferometry with the Hale Telescope to resolve the system in 1977. The Hipparcos satellite observed the orbital motion of the primary relative to other stars, and an orbit was computed in 2005 using spectroscopic data together with these measurements. The period of the system is around 410 days. β Herculis has the names Kornephoros, a Greek word meaning "club bearer", and Rutilicus, a corruption of the Latin word titillicus, meaning "armpit".
Zeta Herculis (ζ Her, ζ Herculis) is a binary star system in the constellation Hercules. The primary star is a sub-giant that is somewhat larger than the Sun and has just begun to evolve away from the main sequence. It is orbited by a smaller and fainter star that is separated from the primary by just over 1 arcsec. The stars orbit each other with a period of 34.5 years and a semi-major axis of 1.36". Stars A & B are separated each other by an average separation of 14.65 AUs and swing as close as 8 AUs and as far away as 21.3 AUs.
This system forms part of the Zeta Herculis moving group of stars. This group includes: δ Trianguli, φ2 Pavonis, ζ Reticuli, 1 Hydrae, Gl 456, Gl 678, and Gl 9079.
Delta Herculis (δ Her / δ Herculis) is a star in the constellation Hercules. It also has the traditional name Sarin.
Alpha Herculis (α Her / α Herculis) is a multiple star in the constellation Hercules. It also has the traditional name Ras Algethi or Rasalgethi (Arabic: رأس الجاثي ra's al-jaθiyy Head of the Kneeler), and the Flamsteed designation 64 Herculis.
When viewed through a telescope, this system is resolved into two components designated α1 and α2. These two components are more than 500 astronomical units apart, with an estimated orbital period of approximately 3600 years. α1 is a relatively massive red bright giant. α2 is actually a double star system with a primary yellow giant star and a secondary, yellow-white dwarf star. (These components are sometimes designated α Herculis A, Ba and Bb, respectively.)
The angular diameter of the red giant α1 has been measured with an interferometer as 34 ± 0.8 milli-arcseconds, or 0.034 arcseconds. At an estimated distance of 120 parsecs, this corresponds to a radius of about 300 million kilometers (or 188 million miles), or 400 times the size of the Sun. It has a total of about 14 solar masses, and has emitted a sparse, gaseous envelope that extends at least 90 astronomical units.
The star is located at the bottom of the constellation. The traditional name "Head" comes from the fact that in the antiquity Hercules was depicted upside down on the constellation maps.
Mu Herculis is a nearest star system about 27.4 light years from Earth in the constellation Hercules. Its main star, Mu Herculis A (possibly a binary) is fairly similar to the Sun although more highly evolved. Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant. Mu Herculis A and the binary itself pair B-C are separated by 286 AUs. On the other hand stars B-C are separated by 11.4 AUs. Their orbit is quite elliptic (e=0.18) and both stars swing each other between 9.4 and 13.5 AUs.
Xi Herculis is a star located within the constellation of Hercules. Its Declination is 29° 15', Right Ascension is 17h 58m, and Magnitude is 3.7. Xi Herculis is about 160 light-years from Earth. Baraka

Hercules 5

Unless you are an avid stargazer, you might not be sure just where to look for Hercules. While the fifth largest constellation, it isn't very obvious.
And yet Hercules boasts one of the finest collection of binary stars, and two Messier objects as well.
We will make a fine distinction here: the constellation name is Hercules, while the Greek hero is Heracles.
Heracles was named after the greatest of Greek goddesses, Hera. Her name means "Lady" and she was the daughter of Cronus, and sister of Zeus (they were twins). Zeus later changed into a cuckoo and seduced his sister (he had that kind of reputation), and the two were married.
Hera became the Queen of the Heavens: goddess of childbirth, marriage, and of women, she was the most widely beloved of goddesses in antiquity. It would only be natural that the greatest of Greek heroes would be named after her: Heracles means "the glory (or honour) of Hera".
Although named after Hera, Heracles didn't have her immediate respect. Heracles was the son of Zeus and a mortal woman (Alcmene). Hera resented Zeus' philandering nature, and tried to have the child killed. She sent two monstrous snakes to his crib, but the infant strangled them both with his pudgy little hands.
Heracles became a favourite with the gods. Apollo made his bow and arrows; Athene gave him a magnificent robe; Hermes provided him with a sword, and Castor (the greatest warrior) taught him how to use it. Hephaestus, the smithy of the gods, made a golden breastplate for Heracles. Thus armed and protected, Heracles paraded through Greek mythology, performing eight heroic deeds and the Twelve Labours.
In fact, the very word "hero" has links with the names Hera and Heracles. The Romans would change his name to Hercules (and hers to Juno, and Zeus to Jupiter).
"Hercules" came to Italy in his tenth labour. He would later be given credit for abolishing human sacrifice in the land.

The constellation was originally represented as a kneeling man, with a foot on the neighbouring dragon (Draco). Some star names reflect this earlier association.

Is a sprawling constellation just to the west of Lyra. From Vega (alpha Lyrae) swing to the west-southwest eight degrees. This is theta Herculis, a 3.86 magnitude star - which is about typical brightness for the main stars of this constellation.
The principal stars are found farther south. Star hop from theta over to pi Herculis, and then to the southwest (about the same distance from pi Herculis to Vega) is beta Herculis, which is actually the brightest star in the constellation.
Now look southeast and you will come across alpha Ophiuchi (Ras Alhague), at 2.1 magnitude, the brightest star of the region. Alpha Herculis is northwest of this star.
Alpha Herculis is better known as Ras Algethi: The kneeler's head. It is estimated to be from 430 to about 650 light years. Some authorities believe the star to be as large as 400 solar diameters.
This is a fine double: a red (or orange) supergiant and a blue-green giant (see below). The primary is also an irregular variable (see below).

Double stars in Hercules:
Hercules has several binaries with contrasting colours, as well as several close binaries, challenging those with larger telescopes.
Alpha Herculis is a visual binary with a very long period, something like 3600 years. 3.2, 5.4; PA 104, separation 4.6".
Zeta Herculis is a rapid binary with colour contrast, a yellow primary and red companion with a period of 34.45 years: 2.9, 5.5. The 2000 values: PA 12º degrees, and the separation 0.7".
Kappa Herculis is an easily resolved binary: 5.3, 6.5; PA 12 degrees, separation 28.4".
Rho Herculis: two white stars which make a lovely double. 4.6, 5.6; PA 326, separation 4.1".
95 Herculis is a very attractive double with contrasting colours, often described as gold and silver (although you may disagree): 5.0, 5.1; PA 258 degrees, separation 6.3".
99 Herculis is a very close rapid binary: 5.1, 8.4; currently the PA is 92 degrees and the separation 0.3".
100 Herculis is another gorgeous binary of two equal white stars easily resolved. 5.9; 5.9; PA 183 degrees, separation 14.2"
Struve 2319. This is a very beautiful binary of two rather faint stars: 7.2, 7.6; PA 191 degrees, separation 5.4".
Variable stars in Hercules:
Alpha Herculis is an irregular variable with a range from 2.7 to 4.0, with a period of roughly three months.
S Herculis is the brightest long-period variable in Hercules, with a visual magnitude range of 6.4-13.8 every 318.14 days. The maximum for the year 2000 should occur in mid July.

Deep Sky Objects in Hercules:
There are two Messier objects in Hercules: M13 and M92.
M13 (NGC 6205) is a spectacular globular cluster sometimes known as "The Hercules Cluster". It is universally acclaimed as the best globular in the northern hemisphere.
This is a very compact cluster of over a million stars. It is also very old - at an estimated age of ten billion years. It's around 25,000-30,000 light years away.
M13 lies on a line between eta Herculis and zeta Herculis, due west of pi Herculis.
M92 (NGC 6341) is also a globular cluster, located nine degrees northeast of M13, and six degrees directly north of pi Herculis.
M92 is also very striking and worthy of consideration, even if considerably overshadowed by M13.

Hercules 2

The Strong Man or The Kneeling Man

The Brighter Stars of Hercules

The Story
The Birth of Hercules

Hercules was one of the sons produced by Zeus in his many love affairs. Hercules became immortal when Zeus put the infant at the breast of his divine spouse Hera as she slept. It was a sneaky deal. Having suckled the divine milk of the goddess, Hercules became immortal, but ever after he was dogged by the enmity of the goddess, who was irate at the infidelity of her husband Zeus.

The Revenge of Hera

Hera worked to make the life of Hercules a living hell. Since he had become one of the immortals, she could not kill him, but she could make his life miserable. At one point Hera cast a spell on Hercules, such that he fell into a fit of madness and uncontrollable rage. Hercules was immensely tall and strong and skilled with weapons, so that in his madness no one could oppose or control him. Blithering in madness, he slaughtered his children.
Hercules Atonement

Upon coming to himself, Hercules was stricken by grief and remorse at what he had done and appealed to the Oracle at Delphi as to what he could do to atone for the tragedy. The answer he received was that he must serve King Eurystheus of Mycenae for twelve years. It was in fact from the Oracle at this time that Hercules received his name, which is written as "Heracles" in Greek, meaning 'glory of Hera'.
The Labors of Hercules

The tasks that the King set for Hercules, became known as the Twelve Labors of Hercules.

to kill the Nemean Lion.
Hercules did this and took the impenetrable hide of the Lion as his cloak. The Lion itself is memorialized as the constellation of Leo.

to slay the many-headed Hydra.
Hercules did this and thereafter used the blood of the Hydra to poison the tips of his arrows. The constellation of Cancer represents the Crab sent by Hera to distract Hercules in his battle with the Hydra.

to catch the Ceryneian hind.
This was a fabulous deer with golden horns and brass hooves that belonged to the goddess Artemis.

to snare the boar of Erymanthus.
This was a monstrous animal that laid ruin to the vineyards of Arcadia.

to clean out the dung-filled stables of King Augeias of Ellis.

to disperse the monstrous Stymphalian birds.
The birdsinfested the lake near the town of Stymphalus in Arcadia. The birds were huge man-eating creatures with claws and beaks of brass. They shot their feathers out like arrows.

to capture the fire-breathing bull.
The bull was ravaging the island of Crete.

to capture the flesh-eating horses of King Diomedes of Thrace.

to capture the belt of Hippolyte.
This was the magnificient belt belonging to the Queen of the Amazons in Cappadocia.

to steal the cattle of Geryon.
Geryon a monster with three bodies, who ruled in a land far to the west. On the way to accomplish this task Hercules set up the rocks at the Strait of Gibraltar, which became known as the Pillars of Hercules.

to steal the golden apples of the Hesperides.
The apples had been presented as a wedding present to Hera. The dragon that had guarded the apples is represented in the sky as the constellation of Draco.

to fetch the monstrous dog Cereberus from the underworld.
The underworld was the realm of the dead ruled by the God of the Underworld, Hades. The loathsome dog had three heads. Its back was covered with snakes, and it had the tail of a dragon.
The Tragic New Marriage of Hercules

After his labors Hercules married Deianeira, the daughter of King Oeneus. The couple did not live happily ever after, though. One day in their travels Hercules and Deianeira had to cross a river swollen by floods. Hercules swam across but left his wife to be ferried across by a centaur boatman, who attempted to rape Deianeira. Hercules then shot the centaur with one of the arrows poisoned with the Hydra's blood.

The dying centaur extracted his revenge by offering Deianeira his blood, promising that it would act as a love ointment to keep her husband faithful to her.

One day Deianeira began to suspect that Hercules was interested in another woman. So she gave Hercules a shirt on which she had spread some of the dying centaur's blood. Of course the blood was poison, since it was mixed with the blood of the Hydra, which had coated the arrow that struck the centaur down.

The Death of Hercules

When Hercules put on the shirt the poisoned blood began to do its work, burning Hercules' flesh to the bone. Hercules could not die. So he built himself a funeral pyre. He spread his lionskin cloak on the pyre and lay down on it. The flames burned up the mortal part of him, while the immortal part ascended to Mount Olympus, where Zeus set him among the stars.

Hercules 3

Alpha Herculis

Distance (Light Years)
382 ± 126
Visual Magnitude
Color (B-V)
Names For This StarRasalgethi (alternatively Ras Algethi or Rasalegti) derives from the Arabic name for the star Al Ras al Jathiyy, "The Kneeler's Head". The name reflects the way that the constellation of Hercules is usually seen as a kneeling man.
Description of the StarRasalgethi is a cool, red M5Ib-II bright giant or supergiant perhaps 900 times as luminous as the sun and maybe 300 times the diameter of the sun.
Rasalgethi is a multiple star system. The companion Rasalgethi B is itself a binary star. The B star revolves at a distance of 4.8 arc sec from A, that is, about 570 AU with a period of 3600 years.
Rasalgethi A was discovered by Sir William Herschel to be a variable star in 1795. The star varies about 1 magnitude on the time scale of 50 to 150 days.
The star is surrounded by an expanding envelope of material stretching out to about 900 AU from the star. It is estimated that the rate of mass loss is 0.3% of the mass of the sun in 100,000 years.

Hercules 4

In manhood, Hera made Hercules insane by burning down his house and killing his wife and children. When Hercules recovered his sanity, he sought the help from the oracle of Delphi. The oracle told him he must serve his cousin Eurystheus, King of Argos, for 12 years. Hoping to destroy Hercules, Eurystheus set him 12 supposedly impossible tasks, but the hero completed them all. The 12 labors of Hercules were (1) strangling the Nemean Lion that terrorized the valley of Nemea. Hercules killed the lion by thrusting his fist down its throat; (2) striking off the many heads of the poisonous water snake Hydra of Lerna, Cancer joined in on the battle against Hercules; (3 and 4) delivering alive to Eurystheus the terrifying Erymanthian boar and the Arcadian stag, sacred pet of Artemis; (5) killing the man-eating birds of Lake Stymphalis; (6) cleaning in one day the stables of Augeas, King of Elis, which contained 3,000 oxen and had not been cleaned for 30 years. Hercules cleaned the stables by turning two rivers to flood the stables; (7) capturing and bearing on his shoulders to Mycenae the white Cretan bull, sire of the Minotaur; (8) capturing the man-eating mares of Diomedes (a Thracian king and son of the war god Ares) and feeding them the flesh of Diomedes; (9) fetching for Eurystheus' daughter the girdle of the Amazon queen, Hippolyte; (10) killing the three-headed monster Geryon, along with his giant herdsman Eurytion and the two-headed dog Orthrus all in order to capture Geryon's oxen; (11) freeing Prometheus and temporarily bearing the weight of the world for Atlas, who went to fetch for him the golden apples of the Hesperides; (12) descending to the underworld to bring the three-headed dog Cerberus to its master, Hades. After Hercules completed his service to Eurystheus, he took part in the voyage of Jason and the Argonauts to find the Golden Fleece. Hercules died when his second wife accidentally put poison on his robe. She thought that Hercules was being unfaithful and poured a magic potion on his robe that was suppose to restore his love for her. The poison burned his skin, causing him great pain. He tore at his flesh but the potion could not be removed.

Greatest and strongest of the Greek demigods, Hercules was the son of Zeus by a mortal woman (Alcmene) and was hated by Zeus's wife, Hera. He began his life of heroic violence by strangling two serpents while still in his crib. The two snakes were sent by Hera to kill Hercules.

Hercules may have been Gilgamesh, the strong-man hero of ancient Babylon. Like Hercules, Gilgamesh killed an invincible lion and accomplished other great tasks. Gilgamesh also explored the seas of the underworld. Here he meets Utnapishtim, a strange sailor who lives on an island in the center of the underworld sea. Utnapishtim is the survivor of a flood created by the gods.

Hercules 1

The origin of this constellation is so ancient that its true identity was lost even to the Greeks, who knew the figure simply as Engonasin, literally meaning ‘the kneeling one’. The Greek poet Aratus described him as being worn out with toil, his hands upraised, with one knee bent and a foot on the head of Draco, the dragon. ‘No one knows his name, nor what he labours at’, said Aratus. But Eratosthenes, a century after Aratus, identified the figure as Heracles (the Greek name for Hercules) triumphing over the dragon that guarded the golden apples of the Hesperides. The Greek playwright Aeschylus, quoted by Hyginus, offered a different explanation. He said that Heracles was kneeling, wounded and exhausted, during his battle with the Ligurians.

Heracles is the greatest of Greek and Roman heroes, the equivalent of the Sumerian hero Gilgamesh. So it is surprising that the Greeks allotted him a constellation only as an afterthought. One reason may be that he was already sometimes personified as one of the heavenly twins represented by the constellation Gemini, the other twin being Apollo.
The full saga of Heracles is long and complex, as befits a legend that has grown in the telling. Heracles was the illicit son of the god Zeus and Alcmene, most beautiful and wise of mortal women, whom Zeus visited in the form of her husband, Amphitryon. The infant was christened Alcides, Alcaeus or even Palaemon, according to different accounts; the name Heracles came later. Zeus’s real wife, Hera, was furious at her husband’s infidelity. Worse still, Zeus laid the infant Heracles at Hera’s breast while she slept, so that he suckled her milk. And having drunk the milk of a goddess, Heracles became immortal.
As Heracles grew up he surpassed all other men in size, strength and skills with weapons, but he was for ever dogged by the jealousy of Hera. She could not kill him, since he was immortal, so instead she vowed to make his life as unpleasant as possible. Under Hera’s evil spell he killed his children in a fit of madness. When sanity returned, he went remorsefully to the Oracle at Delphi to ask how he might atone for his dreadful deed. The Oracle ordered him to serve Eurystheus, king of Mycenae, for 12 years. It was then that the Oracle gave him the name Heracles, meaning ‘glory of Hera’.
Eurystheus set him a series of ten tasks that are called the Labours of Heracles. The first was to kill a lion that was terrorizing the land around the city of Nemea. This lion had a hide that was impervious to any weapon – so Heracles strangled it to death. He used its own claws to cut off the skin. Thereafter he wore the pelt of the lion as a cloak, with its gaping mouth as a helmet, which made him look even more formidable. The Nemean lion is identified with the constellation Leo.
The second labour was to destroy the multi-headed monster called the Hydra which lurked in the swamp near the town of Lerna, devouring incautious passers-by. Heracles grappled with the monster, but as soon as he cut off one of its heads, two grew to replace it. To make matters worse, a large crab came scuttling out of the swamp and nipped at the feet of Heracles. Angrily he stamped on the crab and called for help to Iolaus, his charioteer, who burned the stumps as each head was lopped to prevent more heads growing. Heracles gutted the Hydra and dipped his arrows in its poisonous blood – an action that would eventually be his undoing. Both the crab (Cancer) and the Hydra are commemorated as constellations.
For his next two labours, Heracles was ordered to catch elusive animals: a deer with golden horns, and a ferocious boar. Perhaps the most famous labour is his fifth, the cleaning of the dung-filled stables of King Augeias of Elis. Heracles struck a bargain with the king that he would clean out the stables in a single day in return for one-tenth of the king’s cattle. Heracles accomplished the task by diverting two rivers. But Augeias, claiming he had been tricked, renounced the bargain and banished Heracles from Elis.
The next task took him to the town of Stymphalus where he dispersed a flock of marauding birds with arrow-like feathers. The survivors flew to the Black Sea, where they subsequently attacked Jason and the Argonauts. Next, Heracles sailed to Crete to capture a fire-breathing bull that was ravaging the land. Some equate this bull with the constellation Taurus. For his eighth and ninth labours, Heracles brought to Eurystheus the flesh-eating horses of King Diomedes of Thrace and the belt of Hippolyte, queen of the Amazons.
Finally, Heracles was sent to steal the cattle of Geryon, a triple-bodied monster who ruled the island of Erytheia, far to the west. While sailing there, Heracles set up the columns at the straits of Gibraltar called the Pillars of Heracles. He killed Geryon with a single arrow that pierced all three bodies from the side, then drove the cattle back to Greece. On route through Liguria, in southern France, he was set upon by local forces who so outnumbered him that he ran out of arrows. Sinking to his knees, he prayed to his father, Zeus, who rained down rocks on the plain. Heracles hurled these rocks at his attackers and routed them. According to Aeschylus, this is the incident that is recorded by the constellation Engonasin, the kneeler.
When Heracles returned from the last of these exploits, the cowardly and deceitful Eurystheus refused to release him from his service because Heracles had received help in slaying the Hydra and had attempted to profit from the stable-cleaning. Hence Eurystheus set two additional tasks, more difficult than those before. The first was to steal the golden apples from the garden of Hera on the slopes of Mount Atlas. The tree with the golden fruit had been a wedding present from Mother Earth (Gaia) when Hera married Zeus. Hera set the Hesperides, daughters of Atlas, to guard the tree, but they stole some of the precious produce. So now the dragon Ladon lay coiled around the tree to prevent any further pilfering.
After a heroic journey, during which he released Prometheus from his bonds, Heracles came to the garden where the golden apples grew. Nearby stood Atlas, supporting the heavens on his shoulders. Heracles dispatched Ladon with a well-aimed arrow, and Hera set the dragon in the sky as the constellation Draco. Heracles had been advised (by Prometheus, says Apollodorus) not to pick the apples himself, so he invited Atlas to fetch them for him while he temporarily supported the skies. Heracles hastily returned the burden of the skies to the shoulders of Atlas before making off with the golden treasure.
The twelfth labour, the most daunting of all, took him down to the gates of the Underworld to fetch Cerberus, the three-headed watchdog. Cerberus had the tail of a dragon and his back was covered with snakes. A more loathsome creature would be difficult to imagine but Heracles, protected from the tail and the snakes by the skin of the Nemean lion, wrestled Cerberus with his bare hands and dragged the slavering dog to Eurystheus. The startled king had never expected to see Heracles alive again. Now, with all the labours completed, Eurystheus had no option but to make Heracles a free man again.
The death of Heracles is a piece of true Greek tragedy. After his labours, Heracles married Deianeira, the young and beautiful daughter of King Oeneus. While travelling together, Heracles and Deianeira came to the swollen river Evenus where the centaur Nessus ferried passengers across. Heracles swam across himself, leaving Deianeira to be carried by Nessus. The centaur, aroused by her beauty, tried to ravish her, and Heracles shot him with one of his arrows tipped with the Hydra’s poison.
The dying centaur offered Deianeira some of his blood, deceitfully claiming that it would act as a love charm. Innocently, Deianeira accepted the poisoned blood and kept it safely until, much later, she began to suspect that Heracles had his eye on another woman. In the hope of rekindling his affection, Deianeira gave Heracles a shirt on which she had smeared the blood of the dying Nessus. Heracles put it on – and as the blood warmed up, the Hydra’s poison began to burn his flesh to the bone.
In agony, Heracles raged over the countryside, tearing up trees. Realizing there was no release from the pain, he built himself a funeral pyre on Mount Oeta, spread out his lion’s skin and lay down on it, peaceful at last. The flames burned up the mortal part of him, while the immortal part ascended to join the gods on Mount Olympus. His father, Zeus, turned him into a constellation, which we know by the Roman name Hercules.
Heracles is depicted in the sky holding a club, his favourite weapon. Some people think that his 12 labours are represented by the 12 signs of the zodiac, but it is difficult to see the connection in some cases.
Hercules is the fifth-largest constellation but is not particularly prominent. Alpha Herculis, a red giant star that varies from third to fourth magnitude, is called Rasalgethi, from the Arabic meaning ‘the kneeler’s head’. The most celebrated object in the constellation is a globular cluster of stars, M13, the best example of such a cluster in northern skies.


The hero's head is traced by a quadrangle of stars: π Her, η Her, ζ Her and ε Her known as the "Keystone" asterism. This quadrangle lies between two very bright stars: Vega in the constellation Lyra and α CrB (Gemma, or Alphecca) in the constellation Corona Borealis. He is the great warrior of Kiaish. The hero's right leg contains two bright stars of the third magnitude: α Her (Ras Algethi) and δ Her (Sarin). The latter is the right knee.
The hero's left leg contains dimmer stars of the fourth magnitude which do not have Bayer designations but which do have Flamsteed numbers.
The star β Her belongs to the hero's outstretched right hand, and is also called Kornephoros.
The Globular Cluster M13 lies on the top of the hero's head, between the stars η Her and ζ Her. It is dim, but may be detected by the unaided eye on a very clear night. There is also M92 which is also a globular cluster. A traditional authentic orientation is with the head as α Herculis, because Ras Algethi literally means "head of the kneeling one." The left hand then points towards Lyra from his shoulder (Delta Herculis), and Beta Herculis forms his other shoulder. His narrow waist is formed by Epsilon and Zeta Herculis. Finally, his left leg (with Theta as the knee and Iota the foot) is stepping on Draco's head, the dragon/snake who Hercules has vanquished and perpetually gloats over for eternities.

Ursa Major 12

Kappa Ursae Majoris (κ UMa / κ Ursae Majoris) is a binary star in the constellation Ursa Major. It is approximately 423 light years from Earth and has the traditional names Talitha Australis, Al Kaprah, and Alphikra Australis.
Both components of the binary star are a white A-type main sequence dwarfs. They have apparent magnitudes of +4.2 and +4.4, which gives the system a combined apparent magnitude of +3.57. The orbital period of the binary is 36 or 74 years, and the two stars are separated by 0.13 arcseconds.
Chi Ursae Majoris (χ UMa / χ Ursae Majoris) is a star in the constellation Ursa Major. It also has the traditional names Alkafzah, Alkaphrah, and El Koprah.
Chi Ursae Majoris is an orange K-type giant with an apparent magnitude of +3.69. It is approximately 196 light years from Earth.
The Spiral Galaxy NGC 3877 (= H I.201), type Sc, in Ursa Major is best found from the 3.7-mag star Chi Ursae Majoris, which is almost exactly 15 arc minutes north of the galaxy.
Upsilon Ursae Majoris (υ UMa / υ Ursae Majoris) is a binary star in the constellation Ursa Major. It is approximately 115 light years from Earth.
The primary component, Upsilon Ursae Majoris A, is a yellow-white F-type subgiant with a mean apparent magnitude of +3.78. It is classified as a Delta Scuti type variable star and its brightness varies from magnitude +3.68 to +3.86 with a period of 3.18 hours. The companion, Upsilon Ursae Majoris B is a magnitude +11.5 star, 11.3 arcseconds away from the primary.
Xi Ursae Majoris (ξ UMa / ξ Ursae Majoris) is a star system in the constellation Ursa Major. It also has the traditional name Alula Australis (The word Alula comes from an Arabic phrase meaning ‘first leap’; the distinctions ‘northern’ (Borealis) and ‘southern’ (Australis) are added in Latin).
On May 2, 1780, Sir William Herschel discovered that this was a binary star system, making it the first such system ever discovered. It was the first visual double star for which an orbit was calculated, when it was computed by Félix Savary in 1828.
The system is composed of a double star whose two components are yellow G-type main sequence dwarfs. The brighter component, Xi Ursae Majoris A, has a mean apparent magnitude of +4.41. It is classified as an RS Canum Venaticorum type variable star and its brightness varies by 0.01 magnitudes. The companion star, Xi Ursae Majoris B has an apparent magnitude of +4.87. The orbital period of the two stars is 59.84 years, and they are currently separated by 1.2 arcseconds, or at least 10 Astronomical Units.
Each component of this double star is itself a spectroscopic binary. B's binary companion, denoted Xi Ursae Majoris Bb, is unresolved, but the binary star is known to have an orbital period of 3.98 days.