jeudi 4 septembre 2008

Auriga 8


Theta Aurigae (θ Aur / θ Aurigae) is a binary star in the constellation Auriga. It is approximately 173 light-years from Earth. Rarely used proper names for this star include the Arabic name Maha-Sim or Mahasim, which is a variant of the Arabic name Al-Mi'sam meaning "wrist" that was used to describe both Eta Aurigae and Theta Aurigae [1].
The primary, θ Aurigae A, is a white A-type main sequence dwarf with an apparent magnitude of +2.7. It's companion, θ Aurigae B, is a yellow G-type main sequence dwarf with an apparent magnitude of +7.2. The two stars are separated by 3.5 arcseconds. A third star, the 11th magnitude θ Aurigae C, is 49 arcseconds away, and is an optical companion.
The mean combined apparent magnitude of the system is +2.65 but the primary is an Alpha2 Canum Venaticorum type variable star so the system's brightness varies from magnitude +2.62 to +2.70 with a period of 1.37 days.
It is known as 五車四 (the Fourth Star of the Five Chariots) in Chinese.

ι Aurigae est une étoile de la constellation du Cocher. Dans l'atlas d'Antonín Bečvář, elle porte le nom traditionnel Hassaleh mais elle est aussi appelée Kabdhilinan.
Iota Aurigae est une géante lumineuse orange de type K avec une magnitude apparente de +2,69. Elle est à environ 512 années-lumière de la Terre.
Elle est appelée 五車一 (La première étoile des cinq chariots) en chinois.

ε Aurigae is a star in the constellation Auriga. It also has the traditional names Haldus, Almaaz, or Al Anz. Epsilon Aurigae is an eclipsing binary, whose brightness varies in apparent visual magnitude between +3.0 and +3.8 with a period of about 9,890 days (~27.1 years). It is approximately 2,000 light years distant.
The visible component is a supergiant belonging to the spectral class A8 and is among some of the most luminous stars within 1000 parsecs of the Sun. Its diameter corresponds to about 100 solar diameters. The other (eclipsing) component is not visible.
The most-favored speculation is that it consists of one or two small stars with a ring of opaque dust set nearly edge-on, producing the observed eclipses of 2 years' duration.
The alternate hypothesis is that it is immense, but of low density, and thus semi-transparent.
One of the phenomena exhibited during the eclipse is that the level of obscuration of the A star by the companion diminishes briefly, as though there were a hole in the companion.
This system was an early candidate for containing a black hole but the two models given above are now preferred.
The next eclipse occurs from 2009-2011, and it is hoped that the extensive observations that will likely be carried out may yield further insights into the nature of this system. Finding the star is not difficult; it is the apex of the isosceles triangle formed as the 'nose' of the constellation Auriga, and is visible throughout the winter at northern latitudes, not far from brilliant, yellow Capella.

η Aurigae is a star in the constellation Auriga. Along with ε and ζ Aurigae, it forms an asterism known as "the kids", from which it gets its Latin traditional name Hoedus II.

ζ Aurigae is a star in the constellation Auriga. It also has traditional names Azaleh, Haedus (or Hoedus), Saclateri, Sadatoni.
Zeta Aurigae is an eclipsing binary, which varies from magnitude +3.61 to +3.99 with a period of 972 days.
The main star is a red supergiant, the companion belongs to the spectral class B8. Zeta Aurigae is approximately 790 light-years from Earth.

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