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 |
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]
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.
{{
cite book}}
: CS1 maint: location missing publisher (
link)
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 |
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]
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.
{{
cite book}}
: CS1 maint: location missing publisher (
link)