lect 11 part 1

lect 11 part 1 - 3/4/2010 Young star clusters give insight...

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3/4/2010 1 Young star clusters give insight into star formation and evolution • Newborn stars may form an open (or galactic) cluster • Stars are held together in such a cluster by gravity • Occasionally a star moving more rapidly than average will escape or “evaporate ” will escape, or evaporate , from such a cluster •A stellar association is a group of newborn stars that are moving apart so rapidly that their gravitational attraction for one another cannot pull them into orbit about one another Astronomers measured apparent brightness and color ratios for the cluster stars, knowing the distance they then derived L and T . By comparing the Evolutionary Tracks with the Model we can derive the age of the cluster
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3/4/2010 2 The gas that must once have formed have dissipated leaving only traces of dusty material that forms reflection nebulae In the HR diagram => all stars are in the main sequence ~50 million years Exploring the interstellar medium at millimeter wavelengths • Dark nebulae are hard to detect… • Observing the Galaxy at millimeter wavelengths reveals the cold gas that spawns new stars • In cold gas clouds, atoms combine to form In cold gas clouds, atoms combine to form molecules • Molecular transitions to different Vibrational/rotational states emits photons in the millimeter wavelengths • Carbon monoxide (CO) are easily detectable and ratio to H 2 is constant (CO is a tracer of H
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This note was uploaded on 02/06/2011 for the course ASTR 113 taught by Professor Geller during the Spring '08 term at George Mason.

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lect 11 part 1 - 3/4/2010 Young star clusters give insight...

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