Gamma Velorum
Encyclopedia
Gamma Velorum is a star system
in the constellation
Vela
. At magnitude
+1.7, it is one of the brightest stars in the night sky. It has the traditional names Suhail
and Suhail al Muhlif, which confusingly also apply to Lambda Velorum
. It also has a more modern popular name Regor, which was invented as a practical joke by the Apollo 1
astronaut Gus Grissom
for his fellow astronaut Roger Chaffee. Due to the exotic nature of its spectrum (bright emission lines in lieu of dark absorption lines) it is also dubbed the "Spectral Gem of Southern Skies".
The Gamma Velorum system is composed of at least six stars. The brightest member, γ² Velorum or γ Velorum A, is actually a spectroscopic binary composed of a blue supergiant
of spectral class O9 (30 M☉
), and a massive Wolf-Rayet star
, the heaviest known (10 M☉, originally approx. 40 M☉). The binary has an orbital period of 78.5 days and separation of 1 AU. Its nearest companion, the bright (apparent magnitude +4.2) γ¹ Velorum or γ Velorum B, is a blue-white B-type
subgiant. It is separated from the Wolf-Rayet binary by 41.2", and the separation can easily be resolved with binoculars
.
Gamma Velorum has several fainter companions. The magnitude +8.5 γ Velorum C, a white A-type
star, is 62.3 arcseconds from the A component. At 93.5 arcseconds is the system's second binary star, γ Velorum D and E. The D component is another A-type star which has a magnitude of +9.4. Its companion is a 13th magnitude star, separated by 1.8 arcseconds.
The Chinese name for the star is 天社一 (Mandarin: tiān shè yī), which means "The First Star of the Celestial Altar."
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Vela
Vela (constellation)
Vela is a constellation in the southern sky. Its name is Latin for the sails of a ship, and it was originally part of a larger constellation, the ship Argo Navis, which was later divided into three parts, the others being Carina and Puppis.-Stars:...
. At magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
+1.7, it is one of the brightest stars in the night sky. It has the traditional names Suhail
Suhail
Suhail is an Arabic term meaning handsome, brilliant, noble, glorious, easy-going, and peaceful...
and Suhail al Muhlif, which confusingly also apply to Lambda Velorum
Lambda Velorum
Lambda Velorum is a star in the constellation Vela. It has the traditional name Suhail .Lambda Velorum is a supergiant or bright giant star of spectral class K5...
. It also has a more modern popular name Regor, which was invented as a practical joke by the Apollo 1
Apollo 1
Apollo 1 was scheduled to be the first manned mission of the Apollo manned lunar landing program, with a target launch date of February 21, 1967. A cabin fire during a launch pad test on January 27 at Launch Pad 34 at Cape Canaveral killed all three crew members: Command Pilot Virgil "Gus"...
astronaut Gus Grissom
Gus Grissom
Virgil Ivan Grissom , , better known as Gus Grissom, was one of the original NASA Project Mercury astronauts and a United States Air Force pilot...
for his fellow astronaut Roger Chaffee. Due to the exotic nature of its spectrum (bright emission lines in lieu of dark absorption lines) it is also dubbed the "Spectral Gem of Southern Skies".
The Gamma Velorum system is composed of at least six stars. The brightest member, γ² Velorum or γ Velorum A, is actually a spectroscopic binary composed of a blue supergiant
Blue supergiant
Blue supergiants are supergiant stars of spectral type O or B.They are extremely hot and bright, with surface temperatures of 30,000-50,000 K. They typically have 10 to 50 solar masses on the Hertzsprung-Russell diagram, and can have radii up to about 25 solar radii...
of spectral class O9 (30 M☉
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
), and a massive Wolf-Rayet star
Wolf-Rayet star
Wolf–Rayet stars are evolved, massive stars , which are losing mass rapidly by means of a very strong stellar wind, with speeds up to 2000 km/s...
, the heaviest known (10 M☉, originally approx. 40 M☉). The binary has an orbital period of 78.5 days and separation of 1 AU. Its nearest companion, the bright (apparent magnitude +4.2) γ¹ Velorum or γ Velorum B, is a blue-white B-type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
subgiant. It is separated from the Wolf-Rayet binary by 41.2", and the separation can easily be resolved with binoculars
Binoculars
Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes when viewing distant objects...
.
Gamma Velorum has several fainter companions. The magnitude +8.5 γ Velorum C, a white A-type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
star, is 62.3 arcseconds from the A component. At 93.5 arcseconds is the system's second binary star, γ Velorum D and E. The D component is another A-type star which has a magnitude of +9.4. Its companion is a 13th magnitude star, separated by 1.8 arcseconds.
The Chinese name for the star is 天社一 (Mandarin: tiān shè yī), which means "The First Star of the Celestial Altar."
Etymology
The medieval name Suhail (Al Suhail, Alsuhail, Suhail al Muhlif, Muliphein) is short for the Arabic سهيل المحلف suhayl al-muħlif "The glorious (star) of the oath".External links
- Regor by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois at Urbana-ChampaignUniversity of Illinois at Urbana-ChampaignThe University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...
- NightSky Friday: Rotanev, Derf, Navi, and other Backward Star Names – Space.comSpace.comSpace.com is a space and astronomy news website. Its stories are often syndicated to other media outlets, including CNN, MSNBC, Yahoo!, and USA Today.Space.com was founded by former CNN anchor Lou Dobbs and Rich Zahradnik, in July 1999...
article - Starry Night Photography: Gamma Velorum