Arches Cluster

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Arches Cluster
kpc)
Physical characteristics
Optically obscured
Associations
ConstellationSagittarius
See also: Open cluster, List of open clusters
ESA Hubble Space Telescope
)

The Arches Cluster is the densest known

light-years from its center in the constellation Sagittarius
(The Archer), 25,000 light-years from Earth. Its discovery was reported by Nagata et al. in 1995,[1] and independently by Cotera et al. in 1996.[2] Due to extremely heavy optical extinction by dust in this region, the cluster is obscured in the visual bands, and is observed in the X-ray, infrared and radio bands. It contains approximately 135 young, very hot stars that are many times larger and more massive than the Sun, plus many thousands of less massive stars.[3]

The star cluster is estimated to be around two and a half million years old.

Quintuplet Cluster, it appears to be slightly younger. Only stars earlier and more massive than O5 have evolved away from the main sequence while the Quintuplet Cluster includes a number of hot supergiants as well as a red supergiant and three luminous blue variables.[4]

The most prominent members of the Arches Cluster are hot

eclipsing binary with a Wolf-Rayet primary and a class O supergiant secondary. X-ray emission from the cluster suggests that many other members are also in close binary systems with two hot luminous members, but there is little evidence of the evolution of these stars being affected by binary mass exchange. The spectral classes and their properties merge smoothly from the main sequence to normal class O giants and supergiants, to class O hypergiants, to the presumed most evolved Wolf-Rayets. One star is intermediate between WN8-9h and O4-6 Ia+. There are no cooler evolved stars.[4]

Work by

solar masses was previously deduced by Carsten Weidner & Pavel Kroupa[7] using observations of the cluster R136
.

Prominent stars
B=Blum[8] F=Figer[9] WR#[10] Spectral type[4] Luminosity[11] (L☉) Temperature[11] (effective, K) Mass[12] (M☉) Radius[11] (R☉)
B1 102bc WN8-9h 891,000 31,700 50 - 60 32
F1 102ad WN8-9h 2,000,000 33,200 101 - 119 43
F2 102aa WN8-9h
O5-6 Ia+		 1,000,000 33,500 80[4]
60[4]		 30
F3 102bb WN8-9h 1,260,000 29,600 52 - 63 43
F4 102al WN7-8h 2,000,000 36,800 66 - 76 35
F5 102ai WN8-9h 891,000 32,100 31 - 36 31
F6 102ah WN8-9h 2,240,000 33,900 101 - 119 44
F7 102aj WN8-9h 2,000,000 32,900 86 - 102 44
F8 102ag WN8-9h 1,260,000 32,900 43 - 51 35
F9 102ae WN8-9h 2,240,000 36,600 111 - 131 38
F10 102ab O7-8 Ia+ 891,000 32,200 55 - 69 24
F12 102af WN7-8h 1,580,000 36,900 70 - 82 31
F14 102ba WN8-9h 1,000,000 34,500 54 - 65 28
F15 O6-7 Ia+ 1,410,000 35,600 80 - 97 32
F16 102ak WN8-9h 794,000 32,200 46 - 56 29
F17 102ac O5-6 Ia+
F18 O4-5 Ia+ 1,120,000 36,900 67 - 82 26
F20 O4-5 Ia 794,000 38,200 47 - 57 21
F21 O4-6I 891,000 35,800 56 - 70 25
F22 O4-6I 630,000 35,800 41 - 53 21
F23 O4-6I 630,000 35,800 41 - 52 21
F25[13] O4-5I 851,000 40,000 19
F26 O4-6I 707,000 39,800 45 - 57 18
F28 O4-6I 891,000 39,800 57 - 72 20
F29 O4-6I 562,000 35,700 36 - 45 20
F32 O4-6I 707,000 40,800 47 - 59 17
F33 O4-6I 707,000 39,800 45 - 57 18
F34 O4-6I 562,000 38,100 36 - 46 18
F35 O4-6I 501,000 33,800 34 - 43 21
F40 O4-5 Ia+ 562,000 39,500 57 - 72 16

See also

References

  1. doi:10.1086/117395
    .
  2. doi:10.1086/177099
    .
  3. ^
    S2CID 14412034
    .
  4. ^
    S2CID 53362252
    .
  5. S2CID 4417561
    .
  6. S2CID 118475820
    .
  7. doi:10.1111/j.1365-2966.2004.07340.x
    .
  8. S2CID 2957272
    .
  9. S2CID 119002004
    .
  10. S2CID 119104786
    .
  11. ^
    S2CID 7509876
    .
  12. S2CID 59396651
    .
  13. doi:10.1093/mnras/stad449
    .

External links
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