Super star clusters

Super star clusters (small bright points) in a Hubble Space Telescope image of the galaxy Arp 220

Super star clusters are young, very compact star clusters with a mass between 10,000 and a million solar masses and an age of less than 10 million years. Due to a large number of main sequence stars of the spectral class O and supernovae , the super star clusters are surrounded by ionized H-II regions and their properties correspond to the Ultra dense H-II regions (UDHIIs) in the Milky Way .

Emergence

The first super star clusters were discovered in the 1960s and have since been observed in all types of galaxies with high star formation rates - that is, in starburst galaxies , interacting galaxies , amorphous galaxies and some dwarf galaxies . In contrast to the "normal" formation of 50–500 stars in open star clusters , they are the result of a particularly intense star formation, the starburst . A short-term extremely high star formation rate results in very massive, compact clusters that are slightly less durable than the even more compact globular clusters in the halo of our Milky Way.

properties

The star formation normally takes the form of stellar associations or in giant molecular clouds embedded star clusters that some 10 to contain several million stars. The typical diameter of the open star clusters is 2-10 parsecs , and most aggregations dissolve within a period of 10 million years, when gravity can no longer hold the stars together after the loss of the embedded gas.

Super star clusters have a radius of 2 to 3 parsecs and are considered to be the precursors of globular clusters . A special characteristic is a pronounced infrared excess due to strong absorption in the young star cluster and a high electron density of .. K cm due to the intense UV radiation from young, massive stars. ${\ displaystyle P /}$ ${\ displaystyle k_ {b}}$ ${\ displaystyle = 10 ^ {7}}$ ${\ displaystyle 10 ^ {10}}$ ${\ displaystyle ^ {- 3}}$

In addition, the young stars embedded in super star clusters are responsible for the formation of strong stellar winds . These winds are accelerated far beyond the escape speed and, in the case of dwarf galaxies, remove all gas masses from their home galaxy, so that star formation comes to a standstill.

Examples

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

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

- Ben Ritchie, first author of the study in the journal "Astronomy and Astrophysics"

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

Web links

View of a galaxy's starburst story , on astronews.com, April 3, 2011.
New black hole riddles: Astronomers question popular theories , Scienexx / Springer, April 3, 2011.

Individual evidence

^ Richard Wünsch et al .: Evolution of Super Star Cluster Winds with Strong Cooling . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1107.5451 .

^ F. Martins, NM Förster Schreiber, F. Eisenhauer, and D. Lutz: Near-Infrared spectroscopy of the super star cluster in NGC1705 . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1209.3910 .

^ Carsten Weidner, Ian A. Bonnell and Hans Zinnecker: SUPER-STAR CLUSTERS VERSUS OB ASSOCIATIONS . In: Astrophysics. Solar and Stellar Astrophysics . 2010, arxiv : 1009.1618 .

↑ A. Adamo, E. Zackrisson, G. Östlin, and M. Hayes: ON THE ORIGIN OF THE RED EXCESS IN VERY YOUNG SUPER STAR CLUSTERS: THE CASE OF SBS 0335-052E . In: Astrophysics. Solar and Stellar Astrophysics . 2010, arxiv : 1010.3703 .

↑ SM Dougherty, JS Clark, I. Negueruela, T. Johnson, and JM Chapman: Radio emission from the massive stars in the Galactic Super Star Cluster Westerlund 1 . In: Astrophysics. Solar and Stellar Astrophysics . 2009, arxiv : 0912.4165 .

↑ First super star cluster discovered in our galaxy , Raumfahrer.net, April 2, 2004

↑ Superstar Cluster R136 on meta-evolutions.de, April 3, 2011

[1] Richard Wünsch et al .: Evolution of Super Star Cluster Winds with Strong Cooling . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1107.5451 .

[2] F. Martins, NM Förster Schreiber, F. Eisenhauer, and D. Lutz: Near-Infrared spectroscopy of the super star cluster in NGC1705 . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1209.3910 .

[3] Carsten Weidner, Ian A. Bonnell and Hans Zinnecker: SUPER-STAR CLUSTERS VERSUS OB ASSOCIATIONS . In: Astrophysics. Solar and Stellar Astrophysics . 2010, arxiv : 1009.1618 .

[4] A. Adamo, E. Zackrisson, G. Östlin, and M. Hayes: ON THE ORIGIN OF THE RED EXCESS IN VERY YOUNG SUPER STAR CLUSTERS: THE CASE OF SBS 0335-052E . In: Astrophysics. Solar and Stellar Astrophysics . 2010, arxiv : 1010.3703 .

[5] SM Dougherty, JS Clark, I. Negueruela, T. Johnson, and JM Chapman: Radio emission from the massive stars in the Galactic Super Star Cluster Westerlund 1 . In: Astrophysics. Solar and Stellar Astrophysics . 2009, arxiv : 0912.4165 .

[raumfahrer.net-6] First super star cluster discovered in our galaxy , Raumfahrer.net, April 2, 2004