Super star cluster

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A super star cluster (SSC) is a very large region of star formation thought to be the precursor of a globular cluster.[1] They typically contain a very large number of young, massive stars that ionize a surrounding H II region, similar to our Milky Way's so-called "Ultra dense H II regions (UDHIIs)"[2]. An SSC's H II region is in turn surrounded by a cocoon of dust. In many cases, the stars and the H II regions will be invisible to optical observations due to high levels of extinction. As a result, the youngest SSCs are best observed in radio and infrared.[3]

The unique characteristics of SSCs are their large electron densities ne = 103–106 cm − 3 and pressures P / kb = 107–1010 K cm − 3.[3]

While there are many examples of SSCs in other galaxies, Westerlund 1 may be the only cluster in the Milky Way deserving of the title.[4]

[edit] References

  1. ^ Gallagher & Grebel (2002). "Extragalactic Star Clusters: Speculations on the Future". Extragalactic Star Clusters, IAU Symposium: 207. 
  2. ^ Kobulnicky & Johnson (1999). "Signatures of the Youngest Starbursts: Optically Thick Thermal Bremsstrahlung Radio Sources in Henize 2-10". ApJ 527: 154–166. doi:10.1086/308075. 
  3. ^ a b Johnson (2004). "Extragalactic Ultracompact HII Regions: Probing the Birth Environments of Super Star Clusters". Astronomical Society of the Pacific Conference Series 527: 322. 
  4. ^ "Young and Exotic Stellar Zoo: ESO's Telescopes Uncover Super Star Cluster in the Milky Way", ESO, March 22, 2005. Retrieved on 2007-03-20. 

[edit] External links


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