Dandelion and Gecko of the Night Sky

Millions of years ago, a dust cloud over 5,000 light-years from the sun coalesced to begin the process of star birth. Today, over 190 million years later, NGC 6520 is ablaze with hot, massive young stars arrayed in a dandelion-seed-shaped cluster. Not far away lies the gecko-shaped remains of what may be their birth cloud, in this case, the molecular cloud, Barnard 86.

This image, taken with the Gemini Multi-Object Spectrograph on the ground-based Gemini South Observatory, shows details in a 9.7-by 5.4-arcmin section of a larger, highly populated region in the Sagittarius star cloud. The image provides the clearest optical view of the cluster and its nearby dark-cloud companion.

The total mass of the stars in NGC 6520 is roughly equivalent to 300 to 400 times the mass of the sun, while the nearby cloud contains enough material to make about 3,000 more stars like the sun. The close proximity between the star cluster and its nearby dark-cloud companion suggests the two are related.

A survey of the southern sky released in 2001 singled out hydrogen-alpha emissions from warm, ionized interstellar gas that revealed a nebula extending from the dark globule to embrace the star cluster.

The Gemini Observatory is an international collaboration supported by the National Science Foundation in the United States and counterparts in the U. K., Canada, Chile, Australia, Brazil and Argentina.

- Peter Michaud, Gemini Observatory

Image credit: Gemini Observatory/Association of Universities for Research in Astronomy