Ministerio de Economía y Competitividad Gobierno de Canarias Universidad de La Laguna CSIC Centro de Excelencia Severo Ochoa

Talks and Theses


Past talks

Special Seminar - Formation of Star Clusters.

Dr. Bruce Elmegreen , IBM Watson Research Center, USAThursday - April 19, 2007, 12:30 - Aula IACOther

Clusters are the dense inner regions of a wide-spread hierarchy of young stellar structures. They often reveal a continuation of this hierarchy inside of them, to smaller scales, when they are young, but orbital mixing eventually erases these subparts and only a smooth cluster or unbound group remains.  The stellar hierarchy follows a similar structure in the interstellar gas, which is presumably scale-free because of supersonic motions in the presence of turbulence and self-gravity.  The efficiency of star formation increases automatically with density in a hierarchical ISM, causing most dense stellar groups to be initially bound for local conditions. In low pressure environments, the infant mortality rate should be high and a high proportion of stars should form in unclustered OB associations. In starbursts, where the pressure is high, the reverse should be true: a higher proportion of stars form in bound clusters.  Also following from hierarchical structure is the cluster mass distribution function and perhaps also the cluster size distribution function.  The timescale for cluster formation is generally fast, a few internal dynamical times. There is little evidence for star formation in equilibrium clouds supported by internal stellar pressures.


IBM Research Division
T.J. Watson Research Center
1101 Kitchawan Road
Yorktown Heights New York 10598 USA
University of Wisconsin 1967-1971, B.S. degree 1971, major in Physics and Astronomy
Princeton University 1971-1975, Ph.D. degree 1975, Astrophysics
National Science Foundation Pre-Doctoral Fellowship 1971-1974
Junior Fellowship, Harvard Society of Fellows 1975-1978
National Science Foundation, National Needs Fellowship, 12 months, Spring 1979, Spring 1980
American Astronomical Society, Royal Astronomical Society, International Astronomical Union
Dannie Heineman Prize of the American Physical Society (2001)
Research Sta® Member, IBM, May 1984 to present
Editor, Fundamentals of Cosmic Physics, 1983 to 2000.
Assistant Professor, Columbia University, 1978-1984
Visiting Scientist, Spitzer Space Center, October 2006
Lecturer, \The 7th Guo Shoujing Summer School on Astrophysics: Molecular Clouds and Star Formation,"
Wuxi, China June - July 1993 (5 lectures to Graduate Students and Faculty)
Lecturer, III Canary Islands Winter School, \Star Formation in Stellar Systems," Tenerife, Spain, December
1991 (5 lectures to Graduate Students and Faculty)
Visiting Scientist, University of Paris, Meudon, August 1991
Lecturer, SAAS FEE Series, \The Interstellar Medium in Galaxies," les Diablerets, Switzerland, March
1991 (10 lectures to Graduate Students and Faculty)
Visiting Scientist, Onsala Space Observatory, August 1989
Co-Organizer and visiting scientist, Institute for Theoretical Physics, Santa Barbara, California, August-
October 1985
Lecturer, Les Houches Summer School, \Birth and Infancy of Stars," Les Houches, France, August 1983
Visiting Scientist, University of Sussex, England, September-October, 1981
Visiting Scientist, Cambridge University, England, November-December, 1981
Visiting Associate Professor, University of California at Berkeley, Winter Quarter 1981
Lecturer, Summer School for CNES, \The Formation of Planetary Systems," Grasse, France, August, 1980
(8 lectures to Graduate Students and Faculty)
Publications Board Chair and Council, 1998-2001

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