01/17/2013 – Ephemeris – The blue super-giant star Rigel
Ephemeris for Thursday, January 17th. The sun will rise at 8:14. It’ll be up for 9 hours and 16 minutes, setting at 5:31. The moon, 1 day before first quarter, will set at 12:41 tomorrow morning.
Tuesday I talked about the star Betelgeuse the bright red star in the top left of Orion’s upright rectangle. Orion is seen in the south in the evening. The blue-white star in Orion’s opposite corner is usually brighter. It is Rigel whose longer Arabic name of which Rigel is the first part means Left Leg of the Giant. Rigel is a giant itself, actually a super giant star, which is more a measure of its mass than its size, that of 50 solar masses. Its surface temperature is more than twice as hot as the sun. It is 57 thousand times as bright as the sun and 50 times its diameter. Its distance is 860 light years. Those with telescopes might be able to spot a close companion star to Rigel, just at the edge of the bright arc light image of Rigel itself.
Addendum
Rigel in the winter circle of bright winter stars plus Jupiter.this year. Created using Stellarium.
Bob Moler's Ephemeris Blog 