File:Andromeda_constellation_map.svg · Wikimedia Commons · See Wikimedia Commons
Alpha Andromedae
Sign in to saveAlso known as Alpheratz, Sirrah, 21 Andromedae, HD 358, YPAC 1, 21 And, α And, α Andromedae
Alpheratz is a prominent star system in the constellation of Andromeda. Pronounced , it has the Bayer designation Alpha Andromedae, Latinised from α Andromedae, and abbreviated Alpha And or α And, respectively. Alpheratz is the brightest star in the constellation when Mirach (βAndromedae) undergoes its periodical dimming. Immediately northeast of the constellation of Pegasus, it is the upper left star of the Great Square of Pegasus. It is located at a distance of 97 light-years from Earth.
Wikidata facts
- Distance from Earth
- 97
- Diameter
- 3450000
- Radius
- 2.8
- Mass
- 3.6
- Image
- Alpheratz.gif
Show 17 more facts
- Commons category
- Alpha Andromedae
- spectral class
- B9 Mn Hg
- catalog code
- SKY# 244
- stellar rotational velocity
- 50
- parallax
- 33.60
- absolute magnitude
- -0.307
- luminosity
- 200
- right ascension
- 2.096916186
- apparent magnitude
- 2.37
- declination
- 29.090431118
- effective temperature
- 13076
- radial velocity
- -22.5
- metallicity
- 0.43
- surface gravity
- 3000
- right ascension component of proper motion
- 136
- declination component of proper motion
- -162
- age estimated by a dating method
- 60
via Wikidata · CC0
~8 min read
Article
9 sectionsContents
- Nomenclature
- System
- Chemical peculiarities
- Variability of primary
- Observation
- Optical companion
- Notes
- References
- External links
Alpheratz is a prominent star system in the constellation of Andromeda. Pronounced , it has the Bayer designation Alpha Andromedae, Latinised from α Andromedae, and abbreviated Alpha And or α And, respectively. Alpheratz is the brightest star in the constellation when Mirach (βAndromedae) undergoes its periodical dimming. Immediately northeast of the constellation of Pegasus, it is the upper left star of the Great Square of Pegasus. It is located at a distance of 97 light-years from Earth.
Although it appears to the naked eye as a single star with overall apparent visual magnitude +2.06, it is actually a binary system composed of two stars in close orbit. The chemical composition of the brighter of the two stars is unusual as it is a mercury-manganese star whose atmosphere contains abnormally high abundances of mercury, manganese, and other elements, including gallium and xenon. It is the brightest mercury-manganese star known.