Super star cluster

Super star clusters are young, very compact star with a mass between 10,000 and one million solar masses at an age of less than 10 million years ago. Through a large number of main-sequence stars of spectral type O and supernovae, the super star clusters are surrounded by ionized H II regions and nature corresponds to the ultra dense H II regions ( UDHIIs ) in the Milky Way.

Formation

The first super star clusters were discovered in the 1960s and has since been observed in all types of galaxies with high star formation rates - so in starburst galaxies, interacting galaxies, amorphous galaxies and some dwarf galaxies. In contrast to "normal" development of 50-500 stars in open star clusters are the result of a particularly intense star formation of starburst. By briefly extremely high rate of star formation occur very massive, compact clusters, but are slightly less durable than the more compact globular clusters in the halo of our Milky Way.

Properties

The star formation is usually in the form of stellar associations or in giant molecular clouds embedded star clusters, containing between some 10 and up to several million stars. The typical diameter of the open star cluster located at 2-10 parsecs and most aggregations released over a period of 10 million years ago when the gravity the stars after the loss of the embedded gas can no longer hold together. Super star clusters have a radius of 2-3 parsecs and are considered precursors of globular clusters. As a special feature, a pronounced infrared excesses are due to a strong absorption in the young star clusters and a high electron density of - K cm due to the intense UV radiation by young massive stars.

In addition, the embedded super star clusters young stars are responsible for the formation of strong stellar winds. The stellar winds are accelerated far beyond the escape velocity and in the case of dwarf galaxies they remove all the gas masses from their home galaxy, so that the star formation stops.

Examples

A super star clusters in our Galaxy is Westerlund 1 Westerlund 1 contains hundreds of very massive stars, some of them have up to one million times the solar luminosity and about 2,000 solar diameters, which is about an expansion would correspond to the radius of the orbit of Saturn.

" If the sun is located in the heart of this remarkable cluster, the night sky on earth would be littered with hundreds of stars that would be as bright as the full moon. "

Another example in the galactic neighborhood is R136 in the Tarantula Nebula of the Large Magellanic Cloud, one of the Milky Way orbiting dwarf galaxies.