Alpha Andromedae


Distance (Light Years) 97.1 ± 2.1
Apparent Magnitude 2.07
Color (B-V)-0.11

Names For This Star

Other names for this star are Alpherat, Sirrah, or Sirah. These names derive from the Arabic phrase Al Surrat al Faras meaning "The Horse's Navel." The name is appropriate to the location of the star in the figure of Pegasus, The Flying Horse. However, the star is now considered to belong to the constellation of Andromeda, and indeed the Arabian astronomers also designated this star as Al Ras al Mar'ah al Musalsalah meaning "The Head of the Woman in Chains."

Description of the Star

Alpheratz A is a blue B8IVpMnHg subgiant star, peculiar because of the unusual strength of mercury and manganese in its spectrum. The star is 5 times larger than the sun in diameter and 110 times more luminous.

The spectrum shows that the star has a companion orbiting with 96.7 day period. According to Burnham the spectrum of the companion has not been determined. The The Bright Star Catalog gives no information.

Other Designations For This Star


21 Andromedae

Hipparcos Identifier (HIP Number)


Harvard Revised (HR Number)


Henry Draper Catalog (HD Number)


Bonner Durchmusterung (BD Number)

BD+28 4
Smithsonian Astrophysical
Observatory compendium (SAO Number)

Fundamental Katalog (FK5 Number)



Copyright © 1998 - 2010 by Arnold V. Lesikar,
Professor Emeritus
Dept. of Physics, Astronomy, and Engineering Science,
St. Cloud State University,St. Cloud, MN 56301-4498

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