Loading AI tools
Star in the constellation Canis Major From Wikipedia, the free encyclopedia
Eta Canis Majoris (η Canis Majoris, abbreviated Eta CMa, η CMa), also named Aludra /əˈluːdrə, əˈljuːdrə/,[10] is a star in the constellation of Canis Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[11]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 24m 05.70228s[1] |
| Declination | –29° 18′ 11.1798″[1] |
| Apparent magnitude (V) | 2.450[2] |
| Characteristics | |
| Spectral type | B5 Ia[3] |
| U−B color index | −0.708[2] |
| B−V color index | −0.087[2] |
| Variable type | α Cyg[4] |
| Astrometry | |
| Radial velocity (Rv) | 41.1[5] km/s |
| Proper motion (μ) | RA: −4.14[1] mas/yr Dec.: 5.81[1] mas/yr |
| Parallax (π) | 1.64 ± 0.40 mas[1] |
| Distance | approx. 2,000 ly (approx. 600 pc) |
| Absolute magnitude (MV) | −7.0[6] |
| Details | |
| Mass | 18.19[7] M☉ |
| Radius | 54[8] R☉ |
| Luminosity | 135,000 - 174,000[8] L☉ |
| Surface gravity (log g) | 2.00[8] cgs |
| Temperature | 15,000 - 16,000[8] K |
| Rotational velocity (v sin i) | 40[8] km/s |
| Age | 8.3[9] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
η Canis Majoris (Latinised to Eta Canis Majoris) is the star's Bayer designation.
The traditional name Aludra originates from the Arabic: العذراء al-adhraa, 'the virgin'. This star, along with Epsilon Canis Majoris (Adhara), Delta Canis Majoris (Wezen) and Omicron2 Canis Majoris (Thanih al Adzari), were Al 'Adhārā (العذاري), 'the Virgins'.[12] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[14] included a table of the first two batches of names approved by the WGSN; which included Aludra for this star.
In Chinese, 弧矢 (Hú Shǐ), meaning Bow and Arrow,[15] refers to an asterism consisting of Eta Canis Majoris, Delta Canis Majoris, HD 63032, HD 65456, Omicron Puppis, k Puppis, Epsilon Canis Majoris, Kappa Canis Majoris and Pi Puppis. Consequently, Eta Canis Majoris itself is known as 弧矢二 (Hú Shǐ èr, English: the Second Star of Bow and Arrow).[16]
A blue-white supergiant, Eta CMa has been used as a standard for the spectral type of B5Ia.[18]
Eta CMa shines brightly in the skies in spite of a large distance from Earth due to being intrinsically many times brighter than the Sun. It has a luminosity over 100,000 times and a radius around 54 times that of the Sun. It has only been around a fraction of the time the Sun has, less than 10 million years, yet is already in the last stages of its life. It is still expanding and may become a red supergiant, or perhaps has already passed that phase, but in either case it will become a supernova within the next few million years.[citation needed]
Eta CMa is classified as an Alpha Cygni-type variable star and its brightness varies from magnitude +2.38 to +2.48 over a period of 4.7 days.[4][19]
Both USS Aludra (AF-55), an Alstede-class stores ship, and USS Aludra (AK-72), a Crater-class cargo ship, were U.S. Navy vessels named after the star.
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.
