HD 97950
| HD 97950 | |
|---|---|
HST image of the HD 97950 cluster
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| Observation data (J2000 epoch) | |
| Constellation | Carina |
| Right ascension | 11h 15m 07.346s |
| Declination | −61° 15′ 38.52″ |
| Distance | 25 kly (7.6 kpc) |
| Apparent magnitude (V) | 9.03 |
| Physical characteristics | |
| Mass | 19,000 M☉ |
| Radius | 120" |
| Notable features | Main cluster in NGC 3603 |
| Other designations | HD 97950, NGC 3603YC, CD-60°3452, CPD-60° 2732, HIP 54948, MR 38, WR 43 |
HD 97950, is a multiple star system and part of a super star cluster within the NGC 3603 H II region. It was catalogued as a single star although it was always known to be a compact cluster. It is now resolved into a massive multiple star at the centre of one of the densest clusters in the galaxy.
Only the six lettered stars A-F at the core of the cluster are typically referred to as components of HD 97950, while the remaining stars of the cluster and surrounding area are usually numbered as members of NGC 3603. The cluster itself is still called the HD 97950 cluster as well as the NGC 3603 young cluster (NGC 3603YC). There are no other notable groupings of stars in NGC 3603 and the HD 97950 cluster is often loosely referred to as simply NGC 3603.
The main components are designated A1, A2, A3, B, and C, of which A1 and C are known to be spectroscopic binaries. A1a, A1b, and C are all WN6h Wolf-Rayet Stars, amongst the most massive and luminous known.
There are several dozen early O class stars (O3 and O4) in the cluster, mostly main sequence stars. There are just a handful of giants and supergiants including: one prominent early B supergiant, Sher 25; a highly luminous O3.5 supergiant, Sher 18; and an interesting carbon-rich O9.7 supergiant, Sher 23.
Over 7,500 stars have been identified in the cluster, with the least massive being smaller than the sun and the most massive over 100 M☉. Stars less than about 4 M☉ have not yet reached the main sequence.
The number of WNh and early O stars exceeds any known cluster in the galaxy. The Quintuplet and Arches clusters each have around 20 young massive stars and may have masses comparable to the HD 97950 cluster, but they contain no O3 or WN6 stars at all. The rich red supergiant clusters such as Westerlund 1 are too old to contain such stars, although may be even more massive. R136 in the Large Magellanic Cloud contains stars more massive than any in HD 97950, as well as large numbers of early O stars, and the cluster as a whole may be ten times as massive.
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