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Proper Names	Alpheratz, Sirrah
Bayer Designation	Alpha Andromedae
Flamsteed Number	21 Andromedae
HR (BSC)	15
HD	358
Constellation	Andromeda
Right Ascension	0h 8m 23s
Declination	+29° 5' 26"
Distance	97 light years 30 parsecs
Magnitude	Apparent: +2.1 Absolute: -0.3
Spectral Class	B4IV:pHgMn blue subgiant
Optimum Visibility	October
Notes	Alpheratz is a spectroscopic binary system whose main subgiant star is categorised a variable. In fact, it has shown little evidence of this variability over recent years, but any historical variability is thought to be related to its unusually high levels of mercury, which is unevenly distributed across the star's surface.

A second magnitude star that belongs to both the constellation of Andromeda and the Square of Pegasus. Its brightness is somewhat variable: Alpheratz' luminosity varies as it turns on its axis. It has a companion star, much fainter than the main blue star we see from Earth.

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