HD 97950
WR 43 | |
---|---|
Associations | |
Constellation | Carina |
HD 97950, is the central core of a super star cluster within the NGC 3603 H II region (similar to R136 within the Tarantula Nebula). It was catalogued as a single star, but has now been resolved into one of the densest clusterings of stars 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.
Members
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.[5]
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,
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.[6]
Generally, only the stars with letter naming are typically referred to as components of HD 97950, more stars are listed in NGC 3603.
BLW name | MDS number | Other names | Spectral type | mV | MV | Temperature
(K) |
Luminosity
(L☉) |
Reference |
---|---|---|---|---|---|---|---|---|
A1 | 30 | WR 43a (HSW 1) | WN6h/WN6h | 11.18 | -7.8 | 42,000/40,000 | 2,455,000/1,514,000 | [5][7][6] |
A2 | 31 | HSW 4 | O3V | 12.53 | -6.9 | 46,500 | 1,500,000 | [7][6] |
A3 | 26 | HSW 5 | O3III | 13.09 | -6.4 | 46,500 | 863,000 | [7][6] |
B | 23 | WR 43b (HSW 2) | WN6h | 11.33 | -7.9 | 42,000 | 2,884,000 | [5][6] |
C | 18 | WR 43c (HSW 3) | WN6h | 11.89 | -7.3 | 44,000 | 2,239,000 | [5][6] |
D1 | 49 | O4V | 12.64 | -6.3 | 44,000 | [8][7][6] | ||
D2 | 50 | O5V | 12.74 | -6.2 | 41,000 | [8][7][6] | ||
D3 | 52 | O4V | 13.68 | -5.2 | 44,000 | [8][7][6] | ||
E | 19 | MMM 104 | O5.5III(f) | 12.83 | -6.1 | 41,000 | 1,038,000 | [2][8][7] |
F | 39 | MTT 6 | O5V | 11.86 | -6.1 | 41,000 | [8][7][6] | |
G | 61 | MTT 10 | O5V | 12.74 | -6 | 41,000 | [8][7][6] |
The number of WNh and early O stars exceeds any known cluster in the galaxy. The
It has been proposed that the star
Mass
The HD 97950 cluster has a total photometric mass of 10,000–16,000 M☉,[6] and a dynamical mass of 19,000 M☉.[4] The constituent stars have apparently dynamical segregated with the more massive stars predominantly found at the centre of the cluster.[4] The centre of the cluster has a density of 60,000 M☉ pc−3, ten times the Orion Nebula and comparable to R136.[6]
Age
Fitting the main sequence, and pre-main sequence gives a cluster age of 1 million years or less. There is no clear main sequence turnoff, although the most massive stars are modelled best with an age of 2.5 million years, but are compatible with an age around one million years.[6] A small number of stars, for example Sher 25, apparently show much greater ages and it has been suggested that there is either ongoing star formation, or an earlier burst of star formation.[2] Other studies have estimated ages up to 2 million years, but the existence of the most massive and luminous stars provide a hard upper limit of 2.5 million years on the possible age.[11]
This is one of the youngest clusters in the galaxy. The Arches Cluster is around 2.5 million years old, the Quintuplet cluster nearly double that, and the various open clusters containing red supergiants obviously even older. Even R136 is thought to be near to 2 million years old. Trumpler 14 in the Carina Nebula is thought to be as little as 300,000 - 500,000 years old, but is much less massive.[9]
References
- ^ Bibcode:2003yCat.1289....0Z.
- ^ S2CID 16765414.
- Bibcode:2002yCat.2237....0D.
- ^ S2CID 119199840.
- ^ S2CID 53001712.
- ^ S2CID 17905999.
- ^ doi:10.1086/174891.
- ^ S2CID 18172086.
- ^ S2CID 119207843.
- S2CID 56103308.
- S2CID 5520745.