Haldan Cohn Astronomy Department Indiana University Swain West 319 727 E. Third Street Bloomington, IN  47405 Phone:  812-855-4174 Fax:    812-855-8725 Email:  cohn@indiana.edu

Peering into the Core of a Globular Cluster

Biographical Information:

I have been on the IU Astronomy faculty since 1983. I received an A.B. in Physics from Harvard University in 1975 and a Ph.D. in Astrophysical Sciences from Princeton University in 1979.  I held postdoctoral positions at the Harvard-Smithsonian Center for Astrophysics, the California Institute of Technology, and the University of Illinois before coming to IU.  The courses that I typically teach include A100 (Introduction to the Solar System), A105 (Stars and Galaxies), A451 (Introduction to Astrophysics), and A570 (Galactic Dynamics).

Research Interests:

My research centers on the dynamics of stellar systems, including interacting binary stars, star clusters, the Milky Way Galaxy, galactic nuclei, and clusters of galaxies.  Phyllis Lugger and I lead a research program in these areas which includes both theoretical and observational components.  The theoretical studies use high-performance computers at IU, including a recently acquired GRAPE-6 N-body supercomputer. The observational studies make substantial use of the WIYN telescope, the Hubble Space Telescope, and the Chandra X-ray Observatory.

Our principal research collaborators include Josh Grindlay (Harvard University), Charles Bailyn and Gordon Drukier (Yale University), Adrienne Cool (San Francisco State University), and Brian Murphy (Butler University).  Our former Ph.D. students include Larry David (Harvard-Smithsonian Center for Astrophysics), Brian Murphy, Steve Cederbloom (Mount Union College), Robert Grabhorn, Paul Bode (Princeton University), Jim Dull (Albertson College of Idaho), and Bob Berrington (Naval Research Laboratory). Currently, graduate students Shawn Slavin and Allen Rogel are carrying out Ph.D. dissertation work with us.

Following are some of our current research projects.

• The ChaMPlane Survey: Identification of Chandra X-ray sources in the Galactic plane using WIYN
• Detection and Identification of Chandra X-ray sources in the collapsed-core globular cluster M30
• Analysis of the Chandra X-ray source spatial distributions in normal and collapsed-core globular clusters
• Simulation of star cluster evolution with the GRAPE-6 N-body Supercomputer at Indiana University
• Study of the global dynamics of globular clusters using WIYN

Recent Publications:

• Lugger, P.M., Cohn, H.N., Rogel, A.B., Slavin, S.D., Grindlay, J.E. and Zhao, P. 2002, "WIYN/Hydra Spectroscopy of ChaMPlane Fields,"  Bulletin of the American Astronomical Society, 34, 739
• Cohn, H.N., Lugger, P.M., Grindlay, J.E., Edmonds, P.D., Heinke, C.O., Rubenstein, E.P., and Cool, A.M. 2002, "Detection of Chandra X-ray Sources in the Collapsed-Core Globular Cluster M30," Bulletin of the American Astronomical Society, 34, 657
• Grindlay, J.E., Camilo, F., Heinke, C., Edmonds, P., Cohn, H., and Lugger, P. 2002, "Chandra Study of a Complete Sample of Millisecond Pulsars in 47 Tuc and NGC 6397," The Astrophysical Journal, in press.
• Cohn, H.N., Lugger, P.M., Grindlay, J.E., and Edmonds, P.D. 2002, "Hubble Space Telescope/NICMOS Observations of Terzan 5: Stellar Content and Structure of the Core," The Astrophysical Journal, 571, 181
• Berrington, R.C., Cohn, H.N., and Lugger, P.M. 2002, "The Dynamics of the Merging Galaxy Cluster A2256," The Astronomical Journal, 123, 2261
• Edmonds, P.D., Grindlay, J.E., Cohn, H.N., and Lugger, P.M.  2001, "Stellar Variability in the Metal-Rich, Obscured Globular Cluster Terzan 5," The Astrophysical Journal, 547, 829
• Drukier, G.A., Cohn, H.N., Lugger, P.M., and Yong, H.  1999, "Anisotropic Fokker-Planck Models for the Evolution of Globular Star Clusters: The Core-Halo Connection," The Astrophysical Journal, 518, 233
• Edmonds, P.D., Grindlay, J.E., Cool, A., Cohn, H., and Lugger, P., and  Bailyn, C. 1999, "Cataclysmic Variables and a Candidate Helium White Dwarf in the Globular Cluster NGC 6397," The Astrophysical Journal, 516, 250

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