Roberta Humphreys

woman with glasses

Roberta Humphreys

Professor Emerita, School of Physics and Astronomy


John T. Tate Hall
Room 285-07
116 Church Street Se
Minneapolis, MN 55455


Minnesota Institute for Astrophysics (MIfA)


Ph.D., University of Michigan, 1969

B. A., Indiana University, 1965 

Professional Background

  • NASA Senior Review of the Hubble Space Telescope 2019
  • NASA Senior Review of the Hubble Space Telescope, 2014
  • AAS Henry Norris Russell Prize Committee, 2011-2013
  • Chair SOC for Workshop on Outstanding Problems in Massive Star, 2012
  • Faculty Senate 2007-2010
  • Space Telescope Institute Council (AURA) 2004-2010
  • University of Minnesota Member Representative to AURA 2001- 2010
  • Associate Dean for Academic Affairs, Institute of Technology, 2002-2007
  • AURA Nominating Committee 2006
  • NASA Senior Review (The Universe) 2006
  • NVO Science Definition Team 2001-2002
  • NASA Senior Review (Office of Space Science) 2001
  • NSF Special Review Panel for ITR/NVO 2001
  • AAS Nominating Committee 1998-2000, Chair, 2000
  • NSF Special Review for AURA 2000
  • Vice-Chair University/Faculty Senate 1995-96, 1999-2000
  • Senate/Faculty Consultative Committee 1995-96, 1998-2000
  • AAS Tinsley Prize Committee 1994-96, Chair 1995-96
  • NASA UV/Optical Review Panel 1995

Scientific & Professional Societies

  • Honorary Fellow, Royal Astronomical Society
  • Fellow, American Astronomical Society


During the “tenure wars” of 1995-96, when the Board of Regents and central administration tried to revise the tenure code and effectively remove tenure, I was one of the faculty leaders opposing the administration and worked with the AAUP during the collective bargaining campaign. As Associate Dean I was responsible for faculty affairs for the college including promotion and tenure. In 2005 I initiated and served as co-PI on an ADVANCE proposal to NSF for the advancement of women in science and engineering. I also led the organization of 16 Minnesota colleges and universities for the submission of an LSAMP proposal to NSF. The latter was successful.

Research Interests

Roberta Humphreys' studies of “Luminous Stars in Nearby Galaxies” (Papers 1 – VIII) demonstrated the existence of an empirical upper luminosity boundary in the HR Diagram and by implication an upper limit to the masses of stars that could evolve to become red supergiants (Humphreys & Davidson 1979). This upper limit, sometimes called the Humphreys-Davidson limit, was not predicted by theory and greatly influenced future work on massive star evolution. They suggested then and in two subsequent papers (1984, 1994) that massive stars above this limit encountered an instability, possibly due to the opacity-modified Eddington limit, and experienced high mass loss episodes which prevented their evolution to cooler temperatures. The Luminous Blue Variables (LBVs) and stars like eta Car are examples of this high mass loss phase. As part of this work she also obtained the first spectra and IR photometry of individual stars outside the Local Group. In recent years, she has used the HST to study individual evolved, cool stars that define this upper luminosity limit, the cool hypergiants. Using high resolution spectroscopy and multi-epoch imaging, she has found that some of these stars experience localized high mass loss events probably due to large scale convective activity.She also led the Automated Plate Scanner (APS) project for nearly 20 years. One of their major activities was the digitization of the POSS I and creation of the on-line database ( The APS group was the first to use neural networks for object classification. She and her students (Larsen, Parker and Cabanela) have used the database for large scale studies of the Milky Way.

Honors and Awards

  • Fellow, American Astronomical Society, 2021
  • Honorary Fellow, Royal Astronomical Society, 2013
  • Mullen-Spector-Truax Women's Leadership Award, 2008
  • Distinguished Professor, College of Science and Engineering, 2001
  • Humboldt Senior Scientist Award, Federal Republic of Germany, 1988
  • George W. Taylor Research Award, Institute of Technology, 1985
  • Fellow, American Association for the Advancement of Science, 1980

Selected Publications

  1. R. Humphreys, K. Davidson, A.M.S. Richards, L.M. Ziurys, T.J. Jones, and K. Ishibashi, The Mass Loss History of the Red Hypergiant VY CMa, AJ, 2021, 161, 98
  2. R. Humphreys, G. Helmel, T.J. Jones, and M. Gordon, The Mass Loss Histories of the Red Supergiants, AJ, 2020, 160, 145
  3. R. Humphreys, The Complex Upper HR Diagram, in Special Issue, 2019 MDPI, Galaxies, vol. 7, issue 3.
  4. R. Humphreys et al., The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa, ApJ Letters, 2019, 874L
  5. R. Humphreys, K. Davidson, S.D. Van Dyk, and M, Gordon, A Tale of Two Impostors: SN2002kg and SN1954J in NGC 2403, ApJ. 2017, 848, article id. 86
  6. R. Humphreys, K. Davidson, D. Hahn, J.C. Martin, and K. Weis, Luminous and Variable Stars in M31 and M33. V. The Upper HR Diagram, ApJ. 2017, 844
  7. R. Humphreys, K. Weis, K. Davidson, and M. Gordon, On the Social Traits of Luminous Blue Variables", ApJ, 825, 64 (2016)
  8. R. Humphreys, K. Weis, K. Davidson, D.J. Bomans, and B. Burggraf, Luminous and Variable Stars in M31 and M33. II. Luminous Blue Variables, Candidate LBVs, Fe II Emission Line Stars, and Other Supergiants, ApJ, 790, 48H (2014)
  9. R Humphreys, K. Davidson, K. Grammer, N. Kneeland, J.C. Martin, K. Weis, and B. Burggraf, Luminous and Variable Stars in M31 and M33. I. The Warm Hypergiants and Post-Red Supergiant Evolution, ApJ,773, 46H (2013)
  10. R. Humphreys and K. Davidson (Eds.), Book: Eta Carinae and the Supernova Impostors, (2012)
  11. R. Humphreys et al., The Photometric and Spectral Evolution of the 2008 Luminous Optical Transient in NGC 300, A.J. 743, 118 (2011)
  12. R. M. Humphreys, T.C. Beers, J.E. Cabanela, S. Grammer, Y-S Lee, and J.A. Larsen, Mapping the Asymmetric Thick Disk. III. The Kinematics and Interaction with the Galactic Bar, (2011)
  13. R. M. Humphreys, A. Mehner, K. Davidson, J.C. Martin, K. Ishibashi, G. Ferland, and N. Walborn, A Sea Change in Eta Carinae", A.J. Letters (2010)
  14. R. M. Humphreys, K. Davidson, and M. Koppelman, The Early Spectra of Eta Carinae 1893 - 1941 and the Onset of Its High Excitation Emission Spectrum”, A.J. (2008)
  15. R. M. Humphreys, L.A. Helton, and T. J. Jones , “The 3D Morphology of VY Canis Majoris I. The Kinematics of the Ejecta”, A.J. (2007)
  16. R. M. Humphreys, K. Davidson, G. Ruch and G. Wallerstein, “High-Resolution, Long-Slit Spectroscopy of VY Canis Majoris: The Evidence for Localized High Mass Loss Events”, A.J. (2005)