Much of the star formation in starburst systems has been found to occur in very luminous

Much of the star formation in starburst systems has been found to occur in very luminous

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Much of the star formation in starburst systems has been found to occur in very luminous, compact star clusters (up to 10 8 solar luminosities, dimensions of a few parsecs), which occur in bursting dwarfs, interacting galaxies, and mergers; 30 Doradus in the LMC may also be of this type. Some are apparent in this HST UV image of Markarian 357: Interest in these clusters is strong for several reasons. The Milky Way is not obviously forming stars in this way now, so they may represent a distinct mode of star formation different from the processes we are familiar with in our own neighborhood. If these objects have a "normal" initial mass function and remain gravitationally bound after the mass loss from massive members is complete, they will eventually look a great deal like globular clusters (which the Milky Way doesn't make anymore either). These clusters are the most dense and intense star-forming environments known, and may be analogs of typical objects in the early epochs of galaxy formation. They come as bright as M V =-15 (the nucleus of NGC 4569 may have gotten above -19 in its younger days), with characteristic sizes of a few parsecs. One is often tempted to take giant H II regions as models of starbursts, though the higher gas density in nuclei and increased role for obscuration when so much local material exists will make for differences. Even so, we see nearby luminous H II regions with (30 Doradus) and without (NGC 604) dominant dense star clusters. Starburst mechanisms: Much of the interest in starburst galaxies has been brought on by wondering how some galaxies, and often very small regions in their nuclei, manage to convert so much gas effectively into stars in a very short time. Often there's plenty of molecular gas as judged from CO emission, so it's not a fuelling question so much as a collection puzzle. How can
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Much of the star formation in starburst systems has been found to occur in very luminous

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