Phone(GSFC): 301-286-4533
Phone(STScI): 410-338-4938
Email: hrsproffitt@hrs.gsfc.nasa.gov or proffitt@stsci.edu 

Much of my research has focused on studying chemical diffusion in stars. Currently I am especially interested in the processes that lead to the abundance and isotope anomalies seen in HgMn stars and related types of chemically peculiar stars. It has been presumed that radiation pressure absorbed by the line transitions of rare elements produces these peculiarities, but the detailed physics remains obscure.

I am also interested in diffusion processes in stellar interiors, especially as it effects the evolution of the Sun and globular cluster stars, and in the application of UV spectroscopy to the determination of stellar abundances.

Ph.D. in Physics, University of Washington, 1988
M.S. in Physics, University of Washington, 1983
B.S. in Physics, Massachusetts Institute of Technology, 1981

"Goddard High-Resolution Spectrograph Observations of the B III Resonance et in Early B Stars: Abundances and Isotope Ratios" 1999, Charles R. Proffitt, Per Jönsson, Ulf Litzén, Juliet C. Pickering, Glenn M. Wahlgren, Astrophysical Journal, 516, 342. 

"Very High Resolution UV Spectroscopy of a Chemically Peculiar Star: Results of the chi Lupi Pathfinder Project" 1999, David S. Leckrone, Charles R. Proffitt, Glenn M. Wahlgren, S. G. Johansson, Tomas Brage, Astronomical Journal, 117, 1454. 

"A GHRS Atlas of Echelle Observations of the HgMn Star chi Lupi" 1999, J.C. Brandt, S.R. Heap, E.A. Beaver, A. Boggess, K.G. Carpenter, D.C. Ebbets, J.B. Hutchings, M. Jura, D.S. Leckrone, J.L. L.Y, S.P. Maran, B.D. Savage, A.M. Smith, L.M. Trafton, F.M. Walter, R.J. Weymann, C.R. Proffitt, G.M. Wahlgren, S.G. Johansson, H. Nilsson, T. Brage, M. Snow, T.B. Ake, Astronomical Journal, 117, 1505. 

"Theoretical Oscillator Strengths and Hyperfine Structure in Hg II" 1999, Tomas Brage, Charles R. Proffitt, David S. Leckrone, Astrophysical Journal, 513, 524. 

"Mercury in the HgMn Stars chi Lupi and HR 7775" 1999, Charles R. Proffitt, Tomas Brage, David S. Leckrone, J. C. Brandt, Glenn M. Wahlgren,C. J. Sansonetti, J. Reader, S. G. Johansson, Astrophysical Journal, 512, 942. 

"Theoretical Oscillator Strengths for Sr II and Y III, with Application to Abundances in the HgMn-Type Star chi Lupi" 1998, Tomas Brage, Glenn M. Wahlgren, Sveneric G. Johansson, David S. Leckrone, Charles R. Proffitt, Astrophysical Journal, 496, 1051. 

"Stellar Chemical Abundances With The GHRS" 1996, D. S. Leckrone, S.G. Johansson, G.M. Wahlgren, C.R. Proffitt , Tomas Brage, Physica Scripta, 

"Abundance and Isotopic Anomalies of Thallium in the Atmosphere of the HgMn Star chi Lupi" 1996, David S. Leckrone, Sveneric Johansson, Gabriel Kalus, Glenn M. Wahlgren, Tomas Brage, Charles R. Proffitt, Astrophysical Journal, 462, 937. 

"Effects of heavy-element settling on solar neutrino fluxes and interior structure" 1994, Charles R. Proffitt, Astrophysical Journal, 425, 849. 

"Effects of Diffusion on Solar Models and their Oscillation Frequencies" 1992, J. Christensen-Dalsgaard, C. R. Proffitt, and M. J. Thompson, Astrophysical Journal Letters, 403, L75-L78.

"Helium Gravitational Settling in the Envelopes of Evolving Main Sequence A and F Stars" 1992, J. Richer, G. Michaud, and C. R. Proffitt, Astrophysical Journal Supplement, 82, 329-349.

"Implications of Helium Diffusion for Globular Cluster Isochrones and Luminosity Functions" 1991, C. R. Proffitt and D. A. VandenBerg, Astrophysical Journal Supplement, 77, 473-514.

"Gravitational Settling in Solar Models" 1991, C. R. Proffitt and G. Michaud, Astrophysical Journal, 380, 238-250.

"Diffusion and Mixing of Lithium and Helium in Population II Dwarfs" 1991, C. R. Proffitt and G. Michaud, Astrophysical Journal, 371, 584-601.

"The Lithium Abundance in Cluster Giants: Constraints on Meridional Circulation Transport on the Main-sequence" 1989, by P. Charbonneau, G. Michaud, and C. R. Proffitt, Astrophysical Journal, 347, 821-834.

"Pre-main-sequence Depletion of $^6$Li and $^7$Li" 1989, by C. R. Proffitt and G. Michaud, Astrophysical Journal, 346, 976-982.

"Abundance Anomalies In A and B Stars From the Accretion of Nuclear Processed Material From Supernovae and Evolved Giants" 1989, by C. R. Proffitt and G. Michaud, Astrophysical Journal, 345, 998-1007.

"Stability and Mixing of Composition Inversions in Stellar Envelopes", 1989 by C. R. Proffitt, Astrophysical Journal, 338, 990-1000.

"Theoretical Interpretations of Anomalous Cepheid Pulsations" 1988, by A. N. Cox and C. R. Proffitt, Astrophysical Journal, 324, 1042-1047.

"Blue Companions of Cepheids" 1985, by E. Böhm-Vitense and C. R. Proffitt, Astrophysical Journal, 296, 175-184.

"Ultraviolet Studies of the Stars in the Populous Cluster NGC 2100 in the Large Magellenic Cloud" 1985 by P. Hodge, E. Böhm-Vitense, and C. R. Proffitt, Astrophysical Journal, 292, 130-142.

"Cygnus X-2: Neutron Star or Degenerate Dwarf?" 1984, by J. E. McClintock, L. Petro, G. Hammerschlag-Hensberge, C. R. Proffitt, and R. Remillard, Astrophysical Journal, 283, 794-800.

"UV Analysis of the Peculiar Supergiant HD 112374 = HR 4912" 1984, by E. Böhm-Vitense, and C. R. Proffitt, Publications of the Astronomical Society of the Pacific, 96, 897-902.

"The Problem of the Ba Stars" 1984, E. Böhm-Vitense, J. Nemec, and C. R. Proffitt, Astrophysical Journal, 278, 726-738.

Abstracts and Proceedings:

"GHRS Spectroscopy of Chemically Peculiar Stars: The Chi Lupi Pathfinder Project" 1998, D.S. Leckrone, S.G. Johansson, G.M. Wahlgren, C.R. Proffitt, T. Brage, in The Scientific Impact of the Goddard High Resolution Spectrograph ASP Conference Series; Vol. 143, eds. John C. Brandt; Thomas B. Ake, and Carolyn Collins Petersen, p. 135 

"Selections from the GHRS Atlas of the HgMn Star $\chi$ Lupi" 1998, C. R. Proffitt, T. Brage, G. M. Wahlgren, J. Brandt, D. S. Leckrone, Sveneric Johansson and the GHRS Team in The Scientific Impact of the Goddard High Resolution Spectrograph, eds. J. Brandt, C. C. Petersen, and T. Ake, ASP Conference Series, Vol. 143, p. 322.

"Abundances of Very Heavy Elements in the HgMn Star $\chi$ Lupi" 1998, G. M. Wahlgren, D. S. Leckrone, T. Brage, C. R. Proffitt, and Sveneric Johansson in The Scientific Impact of the Goddard High Resolution Spectrograph, eds. J. Brandt, C. C. Petersen, and T. Ake, ASP Conference Series, Vol. 143, p. 330. 

"Atomic Calculations Inspired by the GHRS - gf-Values, Hyperfine Structure Constants, and Isotope Shifts for Heavy Elements", T., Brage, C.R. Proffitt, G.M. Wahlgren, D.S. Leckrone, S. Johansson, in The Scientific Impact of the Goddard High Resolution Spectrograph ASP Conference Series; Vol. 143; eds. John C. Brandt, Thomas B. Ake, and Carolyn Collins Petersen, p. 378 

"The Importance of Helium and Metals Diffusion in Stars" 1997, by C. R. Proffitt in the book "Fundamental Stellar Properties: The Interaction between Observation and Theory: Proceedings of the 189th Symposium of the International Astronomical Union", eds. T. R. Bedding, A. J. Booth, and J. Davis, Kluwer Academic Publishers: Dordrect, p. 355

"Non-LTE Calculations of Radiative Forces for Thallium in the Atomspheres of HgMn Stars" 1996, by C. R. Proffitt, T. Brage, \& D. S. Leckrone, in the proceedings of the 5th Vienna Workshop on Model Atmospheres and Spectrum Synthesis, (Astronomical Society of the Pacific: San Francisco), Vol. 108, p. 103.

"Mechanisms of Separation of Elements" 1992, by G. Michaud and C. R. Proffitt, in IAU Colloquium 138, Peculiar versus Normal Phenomena in A-type and Related Stars, ed. M. Dworetsky, F. Castelly and R. Faraggiana 

"Coulomb Corrections and Globular Cluster Evolution" 1993, by C. R. Proffitt, in IAU Colloquium 137, Inside the Stars, eds. W. Weiss and A. Baglin, (Astronomical Society of the Pacific: San Francisco), 451-453.

"Particle Transport Processes" 1993, by G. Michaud and C. R. Proffitt, in IAU Colloquium 137, Inside the Stars, , eds. W. Weiss and A. Baglin, (Astronomical Society of the Pacific: San Francisco), 246-259. 

"Mass Accretion and the Internal Structure of T-Tauri Stars" 1991, by C. R. Proffitt in Cool Stars, Stellar Systems, and the Sun, the Seventh Cambridge Workshop, eds. M. S. Giampapa and J. A. Bookbinder, (Astronomical Society of the Pacific: San Francisco), 448-450.

"Diffusion in Metal Poor Low Mass Stars" 1989, by C. R. Proffitt, G. Michaud, and J. Richer, in Cool Stars, Stellar Systems, and the Sun, the Sixth Cambridge Workshop, edG. Wallerstein, (Astronomical Society of the Pacific: San Francisco), 351-352.

"Nonlinear Pulsations of He Stars" 1987, by C. R. Proffitt and A. N. Cox, in Stellar Pulsation, ed. by A. N. Cox, W. M. Sparks and S. G. Starrfield, (Springer Verlag: Berlin) Proceedings of a conference held at the Los Alamos National Laboratory, Los Alamos N.M., U.S.A. 11-15 August 1986, 379-382.

"Theoretical Interpretations of Anomalous Cepheid Pulsations" 1986, by A. N. Cox, and C. R. Proffitt, in Cool Stars, Stellar Systems, and the Sun, the Fourth Cambridge Workshop, eds. M. Zeilik and D. M. Gibson, (Springer Verlag: Berlin), 397-399.

"Light and Velocity Curves of Bump Cepheids" 1986, by C. R. Proffitt and A. N. Cox, in Cool Stars, Stellar Systems, and the Sun, eds. M. Zeilik and D. M. Gibson, (Springer Verlag: Berlin), 400-402.

"The HR Diagram for the Populous Cluster NGC 2100 in the LMC" 1984, by E. Böhm-Vitense, P. Hodge, and C. R. Proffitt, in The Future of Ultraviolet Astronomy with the International Ultraviolet Explorer, NASA Conference Publ., No. 2344, 191-195.

"The White Dwarf Companion of the Mild Barium Star Xi One Ceti" 1984 by E. Böhm-Vitense, C. R. Proffitt, and H. Johnson, in The Future of Ultraviolet Astronomy with the International Ultraviolet Explorer, NASA Conference Publ., No. 2344, 293-294.

"Blue Companions of Cepheids" 1984 by E. Böhm-Vitense, and C. R. Proffitt, in The Future of Ultraviolet Astronomy with the International Ultraviolet Explorer, NASA Conference Publ., No. 2344, 344-347.

"Ultraviolet Observations of the Population II Cepheids ST Pup and W Vir" 1984 by E. Böhm-Vitense, C. R. Proffitt, and G. Wallerstein, in The Future of Ultraviolet Astronomy with the International Ultraviolet Explorer, NASA Conference Publ., No. 2344, 348-351.

"UV Analysis of the Peculiar F Supergiant HD 112374" 1984 by E. Böhm-Vitense, and C. R. Proffitt, in The Future of Ultraviolet Astronomy with the International Ultraviolet Explorer, NASA Conference Publ., No. 2344, 352-354.

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