Sunday, October 29, 2017

Star of the Month - November 2017

Alpha Piscium

This month's star is a challenge, both for your eyesight and for your equipment. Alpha Piscium (a.k.a., Alrescha), although only the 3rd brightest star in Pisces, is the linchpin that (visually, at least) holds the constellation together. You can find it on the star chart below off to the lower left corner.



The star itself is an extremely close binary (only 1.8" of separation) composed of 2 suns, each of which is approximately twice as massive as our own. They shine with a combined luminosity of 42 suns and are about 139 light years from our Solar System. They take nearly 700 years to complete one orbit about each other, and we happen to be living very near their closest approach (which will occur in 2060).

Although Alpha Piscium can be split in amateur telescopes, be prepared for a challenge. By comparison, the individual components of the famous "Double Double" (Epsilon Lyrae) near Vega in the constellation Lyra are separated by 2.6" and 2.3" respectively, and are often used as a test of one's ability to split double stars. So if you can see "daylight" between the 2 stars making up Alpha Piscium, give yourself (and your scope!) a pat on the back.

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