AST101_fall2018_class12_oct16_v2.pdf

Gaensler 35 clicker quiz 60 seconds why do molecular

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AST 101 | UofT | Prof. Gaensler | 35 Clicker Quiz – 60 Seconds Why do molecular clouds collapse? A. They have a lot of mass. B. They are very hot. C. They are very dark. D. They are very dusty. E. They are made of hydrogen and helium.
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AST 101 | UofT | Prof. Gaensler | 19 Squeezing gas makes it hot As the cloud collapses and gets denser, it heats up A star beings to forms in the centre of the cloud, where temperatures and densities are highest Credit: envirogadget.com A Molecular Cloud Collapses (II)
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AST 101 | UofT | Prof. Gaensler | 20 Protostars Credit: Per Bjerkeli / David Lamm / BOID Hot and bright, just like a star But no nuclear fusion occurring in core Gas from surrounding cloud continues to fall down onto the protostar (“accretion”) Can last for a million years
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AST 101 | UofT | Prof. Gaensler | 21 Protostellar Winds Credit: NASA & Hubble Heritage Team (STScI / AURA) A protostar off beyond the right of the image is blowing a wind of gas from right to left You can see this wind “wrap around” another protostar
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AST 101 | UofT | Prof. Gaensler | 22 Protostellar Jets Credits: ESO / M. McCaughrean ; C. Burrows / WFPC2 / ESA / STScI / NASA ; C. Burrows / J. Hester / J. Morse / NASA
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AST 101 | UofT | Prof. Gaensler | 23 The cloud will be slowly rotating in some random direction Even though overall cloud is spinning, individual particles can be moving in random directions Collisions between particles tend to cancel out up, down and elliptical motions Cloud gradually collapses into a spinning pancake-shaped disk (“protostellar disk”) Credit: Rob Crain and the Virgo Consortium A Molecular Cloud Collapses (III)
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AST 101 | UofT | Prof. Gaensler | 36 Clicker Quiz – 60 Seconds Which type of object is not expected near a protostar? A. Jets. B. Winds. C. Molecular gas. D. Planets. E. Dust.
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AST 101 | UofT | Prof. Gaensler | 25 Credit: Rob Crain and the Virgo Consortium A Molecular Cloud Collapses (IV) The winds and jets eventually blow off the surrounding gas No more infalling material “Naked” protostar
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AST 101 | UofT | Prof. Gaensler | 26 What Do We See?
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  • Fall '08
  • MOCHNACKI/ABRAHAM
  • Prof. Gaensler

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