Alpha Andromedae
Alpheratz, or α Andromedae is a bright star in the constellation of Andromeda located on the northeast corner of the asterism known as the Great Square of Pegasus
Naming and mythology
Alpheratz, sometimes called Sirrah, was originally named Al Surrat al Faras, the horse's navel, by Arab astronomers before Ptolemy named the star Al Rās al Marʼah al Musalsalah which represented the head of Andromeda.[1]
Observational attributes
Alpheratz has an apparent magnitude of 2.06[2] and can be located at coordinates R.A. 0h 8m 23.3s and Dec. +29° 5ˈ 26ˈˈ. The parallax for Alpheratz is 0.032ˈˈ translating into a distance from Earth of roughly 101 light years.
Physical characteristics
α Andromedae is a spectroscopic binary star with a main component of magnitude 2.06 and a companion star of magnitude 11.4. The stars orbit each other with a period of 96.7 days.[3] the spectral class of the main star is B8IV with lines of manganese and mercury as well as gallium II apparent in the spectrum. The spectral class indicates a surface temperature for α Andromedae at around 13.000 kelvin and a luminosity of some 200 solar luminosities. The radius of the star is estimated at around 5 times that of the sun.[2]
The main component of α Andromedae is classified as a variable star of the α2 Canum venaticorum variety. Its brightness varies between magnitude 2.02 and 2.06 with a period of 0.966222 days.[4]