Department of Astronomy

Professor Cohn's research centers on the dynamics of stellar systems, including interacting binary stars, star clusters, the Milky Way Galaxy, galactic nuclei, and clusters of galaxies. Professors Haldan Cohn and Phyllis Lugger lead a research program in these areas which includes both theoretical and observational components. The theoretical studies use high-performance computers at IU. The observational studies make substantial use of the WIYN telescope, the Hubble Space Telescope, and the Chandra X-ray Observatory.

Their 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). 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), Bob Berrington (Ball State), Shawn Slavin (Purdue-Calmet) and Allen Rogel (Bowling Green State).

Some of our current research projects include:

• 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

Professor Haldan Cohn has been on the IU Astronomy faculty since 1983. He received an A.B. in Physics from Harvard University in 1975 and a Ph.D. in Astrophysical Sciences from Princeton University in 1979. Professor Cohn held postdoctoral positions at the Harvard-Smithsonian Center for Astrophysics, the California Institute of Technology, and the University of Illinois before coming to IU. He most recently taught A100 (Introduction to the Solar System), A105 (Stars and Galaxies), A451 (Stellar Astrophysics), and A570 (Galactic Dynamics).

Identifications of faint Chandra sources in the globular cluster M3, Zhao, Y., Heinke, C. O., Cohn, H. N., Lugger, P. M., Cool, A. M. 2019, MNRAS, 483, 4560.

The radius of the quiescent neutron star in the globular cluster M13, Shaw, A. W., Heinke, C. O., Steiner, A. W., Campana, S., Cohn, H. N., Ho, W. C. G., Lugger, P. M., Servillat, M. 2018, MNRAS, 476, 4713.

New cataclysmic variables and other exotic binaries in the globular cluster 47 Tucanae*, Rivera Sandoval, L. E., van den Berg, M., Heinke, C. O., Cohn, H. N., Lugger, P. M., Anderson, J., Cool, A. M., Edmonds, P. D., Wijnands, R., Ivanova, N., Grindlay, J. E. 2018, MNRAS, 475, 4841.

Identification of Faint Chandra X-Ray Sources in the Core-collapsed Globular Cluster NGC 6752, Lugger, P. M., Cohn, H., Cool, A. M., Heinke, C. O., Anderson, J. 2017, ApJ, 841, 53.

Anisotropic Fokker-Planck Models for the Evolution of Globular Star Clusters: The Core-Halo Connection, Drukier, G. A., Cohn, H. N., Lugger, P. M., Yong, H. 1999, ApJ, 518, 233.

View a complete list from the Astrophysics Data System