Nearby "Dwarf" Galaxy is Home to Luminous Star Cluster
I personally was amazed at hearing about a young cluster containing more than 7,000 O-type stars. For comparison, Wikipedia says that the entire Milky Way may contain no more than 20,000 O-type stars.A team of Tel Aviv University and UCLA astronomers have discovered a remarkable cluster of more than a million young stars are forming in a hot, dusty cloud of molecular gases in a tiny galaxy very near our own.NGC 5253 as seen by the
Hubble Space Telescope
The star cluster is buried within a massive gas cloud dubbed "Cloud D" in the NGC 5253 dwarf galaxy, and, although it's a billion times brighter than our sun, is barely visible, hidden by its own hot gases and dust. The star cluster contains more than 7,000 massive "O" stars: the most brilliant stars extant, each a million times more luminous than our sun.
"Cloud D is an incredibly efficient star and soot factory," says Prof. Sara Beck of TAU's Department of Astronomy and Astrophysics and co-author of the research, recently published in Nature. "This cloud has created a huge cluster of stars, and the stars have created an unprecedented amount of dust."
Those who are interested in nearby very massive star formation may know that R136 in the Large Magellanic Cloud is the richest young cluster in the Local Group of galaxies. For that reason, I wrote to Sara Beck, who is quoted in the article above, and asked her to compare R136 in the LMC with Cloud D in NGC 5253. Sara Beck wrote back and said that R136 in the LMC contains 350-450 O stars, depending on where you put the boundary. That would make Cloud D in NGC 5253 15-20 times richer in O-type stars than R136, which is absolutely remarkable. The way I understand it, Cloud D in NGC 5253 is more like an extremely young globular cluster than anything else in the nearby universe.
Ann
