HD 93129 is a triple star system in the Carina Nebula, with all three components being hot O class stars amongst the

most luminous stars This is a list of stars arranged by their absolute magnitude – their intrinsic stellar luminosity. This cannot be observed directly, so instead must be calculated from the apparent magnitude (the brightness as seen from Earth), the distance t ...

in the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

. It is the dominant member of the

Trumpler 14 Trumpler 14 (''Tr 14'') is an open cluster with a diameter of , located within the inner regions of the Carina Nebula, approximately from Earth. Together with the nearby Trumpler 16, they are the main clusters of the Carina OB1 stellar associat ...

star cluster Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clust ...

, a young star cluster within the

Carina OB1 Carina OB1 is a giant OB association in the Carina Nebula, which is home to some of the most massive and luminous stars in the Milky Way Galaxy. It includes the young star clusters Collinder 228, NGC 3293, NGC 3324, IC 2581, Trumpler 14, T ...

stellar association that harbors other super-luminous stars, like

Eta Carinae Eta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around distant in t ...

and

WR 25 WR 25 (HD 93162) is a binary star system in the turbulent star-forming region the Carina Nebula, about 6,800 light-years from Earth. It contains a Wolf-Rayet star and a hot luminous companion and is a member of the Trumpler 16 cluster. T ...

Location

HD 93129 is found at the centre of the massive

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

in the Carina Nebula star forming region. It is too far away for its distance to have been accurately determined using the annual parallax method, but accurate distances for

η Carinae Eta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around distant in t ...

and the Homunculus Nebula, modelling of clusters, and astrophysical data about other stars assumed to be within the same region, all lead to a distance around 2,300 parsecs. HD 93129 Aa is the closest O2 supergiant to Earth. That volume of space is home to many other massive and luminous stars.

HD 93128 Trumpler 14 (''Tr 14'') is an open cluster with a diameter of , located within the inner regions of the Carina Nebula, approximately from Earth. Together with the nearby Trumpler 16, they are the main clusters of the Carina OB1 stellar associat ...

, yet another O3.5 main sequence star, is only 24' away within Trumpler 14, and

HD 93250 HD 93250 is a highly luminous hot blue binary star in the Carina Nebula in the constellation Carina. Location HD 93250 is one of the brightest stars in the region of the Carina Nebula. It is only 7.5 arc-minutes from the famous ...

and

HD 93205 HD 93205, or V560 Carinae, is a binary stellar system, in the Carina Nebula (NGC 3372) in the constellation Carina. It consists of two massive O-stars that revolve around each other in 6 days. The more massive member of the pair is ...

are two more O3.5 stars in the larger

Trumpler 16 Trumpler 16 (''Tr 16'') is a massive open cluster that is home to some of the most luminous stars in the Milky Way galaxy. It is situated within the Carina Nebula complex in the Carina–Sagittarius Arm, located approximately from Earth. The c ...

cluster around η Carinae. There are also three Wolf-Rayet stars, an O4

supergiant Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spa ...

, many other class O stars, and the unique η Carinae itself.

System

HD 93129 consists of two clearly resolved components, HD 93129 A and HD 93129 B, and HD 93129 A itself is made up of two much closer stars. HD 93129 A has been resolved into two components. The spectrum is dominated by the brighter component, although the secondary is only 0.9 magnitudes fainter. HD 93129 Aa is an O2 supergiant and Ab is an O3.5 main sequence star. Their separation has decreased from 55 mas in 2004 to only 27 mas in 2013, but an accurate orbit is not available. HD 93129 B is an O3.5 main-sequence star 3 arc-seconds away from the closer pair. It is about 1.5 magnitudes fainter than the combined HD 93129 A, and approximately the same brightness as HD 93129 Ab. A further 5 fainter stars within 5 arc-seconds have been detected, between five and seven magnitudes fainter at

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

wavelengths.

Properties

All three stars of HD 93129 are among the most luminous in the galaxy; for the supergiant primary and for each of the other two stars. They are also among the hottest, with the supergiant at 42,500 K and the other two at 52,000 K. The stars have masses calculated to be between and . HD 93129Aa has left the main sequence and its age is estimated to be around 900,000 years. The existence of the zero-age main sequence stars within Trumpler 14 suggest its age may be less than 600,000 years.

References

External links

* http://jumk.de/astronomie/big-stars/hd-93129a.shtml {{DEFAULTSORT:HD 93129 Carina (constellation) Carina Nebula 093129A 114507 Durchmusterung objects O-type supergiants O-type main-sequence stars Emission-line stars Spectroscopic binaries Triple star systems

Location

System

Properties

See also

References

External links