Faculty | Haldan N. Cohn
Ph.D., Astrophysics, Princeton University, 1979.
Department of Astronomy
Swain West 411
727 East Third Street
Bloomington, IN 47405
Phone: (812) 855-4174
Email: cohn [at] astro.indiana.edu
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. The courses that he typically teaches include A100 (Introduction to the Solar System), A105 (Stars and Galaxies), A451 (Stellar Astrophysics), and A570 (Galactic Dynamics).
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, 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.
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 (University of Wyoming), Shawn Slavin (Purdue-Calmet) and Allen Rogel (Bowling Green State).
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
- Discovery of near-ultraviolet counterparts to millisecond pulsars in the globular cluster 47 Tucanae
Rivera-Sandoval, L. E., van den Berg, M., Heinke, C. O., Cohn, H. N., Lugger, P. M., et al. 2015, MNRAS, 453, 2707.
- A Low-mass Main-sequence Star and Accretion Disk in the Very Faint X-Ray Transient M15 X-3
Arnason, R. M., Sivakoff, G. R., Heinke, C. O., Cohn, H. N., Lugger, P. M. 2015, ApJ, 807, 52.
- Improved Mass and Radius Constraints for Quiescent Neutron Stars in ω Cen and NGC 6397
Heinke, C.O., Cohn, H.N., Lugger, P.M. Webb, N.A., Ho, W.C.G., et al. 2014, MNRAS, 444, 443.
- A Chandra Look at the X-ray Faint Millisecond Pulsars in the Globular Cluster NGC 6752
Forestell, L.M., Heinke, C.O., Cohn, H.N., Lugger, P.M. Sivakoff, G.R., et al. 2014, MNRAS, 441, 757.
- A Deep Chandra X-Ray Limit on the Putative IMBH in Omega Centauri
Haggard, D., Cool, Adrienne M., Heinke, C. O., van der Marel, R., Cohn, H. N., Lugger, P.M., Anderson, J. 2013, ApJ, 773, 31.
- X-Ray Binaries in the Ultrahigh Encounter Rate Globular Cluster NGC 6388
Maxwell, J. E., Lugger, P. M., Cohn, H. N., Heinke, C. O., Grindlay, J. E., Budac, S. A., Drukier, G. A., & Bailyn, C. D. 2012, ApJ, 756, 147.
- An Examination of the X-Ray Sources in the Globular Cluster NGC 6652
Stacey, W. S., Heinke, C. O., Cohn, H. N., Lugger, P. M., & Bahramian, A. 2012, ApJ, 751, 62.
- 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.