dimanche 31 août 2008

Crater 4






The Crater is the goblet of Apollo. Its shape does resemble a drinking glass, slightly askew in the sky, which is why other ancient cultures also saw this group of stars as some kind of vessel. Its stars are generally fourth magnitude.
Alpha Crateris is known as Alkes, Arabian for "shallow basin". The star marks the western corner of the stem, with beta Crateris marking the other corner.
Alkes is an orange (or yellow) giant, about 15 times the diameter of the Sun, and 110 light years away.
The brightest star in the constellation is delta Crateris, which marks the bottom of the bowl. It's about seven times the size of our Sun, and is 73 light years away.







Double stars in Crater:
Gamma Crateris is a fixed binary: 4.1, 9.6; PA 96º, separation 5.2".
Iota Crateris is a close binary: 5.5, 11; PA 226º, separation 1.4".
Psi Crateris is an even closer binary: 6.5, 7; PA 358º, separation 0.2".



Variable Stars in Crater:
None of the Bayer stars of Crater are considered to be variable. The constellation has several semi-regular variables, the brightest of which is R Crateris: 8.0-9.5 with a period of about 160 days.

Aucun commentaire: