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Ofer Cohen

Ofer Cohen headshot
Dr. Ofer CohenAssistant Professor
  • College
    College of Sciences
  • Department
  • Phone
    (978) 934-4913
  • Office
    Olney Hall - 101A
  • Email
  • Profile Links

Research Interests

Heliophysics, Exoplanets, Stellar astrophysics, Space weather, Planetary atmospheres


  • Ph D: Space and Planetary Physics, (2008), University of Michigan, Department of Atmospheric, Oceanic, & Space Sciences - Ann Arbor, MI
    Dissertation/Thesis Title: The Solar Corona through Numerical Eyes
  • MS, (2002), Tel-Aviv University, Department of Geophysics & Planetary Sciences - Tel- Aviv, Israel
  • BS, (2000), Tel-Aviv University, Department of Geophysics & Planetary Sciences - Tel- Aviv, Israel


During his graduate studies Professor Cohen developed a cutting-edge numerical model to study the solar corona and the solar wind. This model has been also used as a prototype for a forecasting system to predict space weather and its impact on satellites, astronauts and space-born technology. After completing his PhD., Professor Cohen moved to the Harvard-Smithsonian center for astrophysics as an NSF fellow. He continued to work on studies of the solar corona, but at the same time began to implement his solar model of other stars in order to study stellar astrophysics problems, such as the spindown and mass-loss rates of low-mass stars. These parameters are very important for stellar evolution, but they cannot be directly measured. Thus, Professor Cohen’s modeling work on stellar winds has provided a significant advancement. In addition, Professor Cohen has been implementing models that have been developed to connect the Earth and solar system objects to the study of exoplanets. This approach provided a much more realistic view on exoplanets and their characteristics. Professor Cohen has established himself as an interdisciplinary researcher who works on many topics falling within the range of planetary science, heliophysics, solar physics and astrophysics. He has served as a scientific reviewer in many review panels of NASA and the NSF, a long list of scientific journals and graduate student and postdoc review panels

Selected Awards and Honors

  • NASA Postdoc Fellowship (NPP) (2016) - NASA
  • NSF Postdoctoral Fellow (2010) - Harvard-Smithsonian CfA

Selected Publications

  • Cohen, O. (2017) "A Comparison Between Physics-based and Polytropic MHD Models for Stellar Coronae and Stellar Winds of Solar Analogs," arXiv preprint arXiv:1701.01146
  • Cohen, O., Yadav, R., Garraffo, C., Saar, S.H., Wolk, S.J., Kashyap, V.L., Drake, J.J., Pillitteri, I. (2017) "Giant Coronal Loops Dominate the Quiescent X-Ray Emission in Rapidly Rotating M Stars," The Astrophysical Journal 834:1 pp. 14
  • Garraffo, C., Drake, J.J., Cohen, O. (2016) "The missing magnetic morphology term in stellar rotation evolution," Astronomy & Astrophysics 595: pp. A110
  • Garraffo, C., Drake, J.J., Cohen, O. (2016) "The Space Weather of Proxima Centauri b," The Astrophysical Journal Letters 833:1 pp. L4
  • Garraffo, C., Drake, J., Cohen, O.!!!, . (2016) "The Missing Magnetic Morphology Term in Stellar Rotation Evolution," ArXiv e-prints
  • Ginsburg, I., Wang, X., Loeb, A., Cohen, O. (2016) "Detecting stars at the galactic centre via synchrotron emission," Monthly Notices of the Royal Astronomical Society 455: pp. L21-L25
  • Cohen, O. (2015) "Quantifying the Difference Between the Flux-Tube Expansion Factor at the Source Surface and at the Alfvén Surface Using a Global MHD Model for the Solar Wind," Solar Physics 290: pp. 2245-2263
  • Garraffo, C., Drake, J., Cohen, O.!!!, . (2015) "Magnetic Complexity as an Explanation for Bimodal Rotation Populations among Young Stars," The Astrophysical Journal, Letters 807: pp. L6
  • Cohen, O., Ma, Y., Drake, J., Glocer, A., Garraffo, C., Bell, J., Gombosi, T.I.!!!, . (2015) "The Interaction of Venus-like, M-dwarf Planets with the Stellar Wind of Their Host Star," The Astrophysical Journal 806: pp. 41
  • Garraffo, C., Drake, J., Cohen, O.!!!, . (2015) "Magnetic Modulation of Stellar Angular Momentum Loss," 18: pp. 177-182
  • Le Chat, G., Kasper, J., Cohen, O., Spangler, S.R. !!!, . (2014) "Diagnostics of the Solar Corona from Comparison between Faraday Rotation Measurements and Magnetohydrodynamic Simulations," The Astrophysical Journal 789: pp. 163
  • Cohen, O., Drake, J., Glocer, A., Garraffo, C., Poppenhaeger, K., Bell, J., Ridley, A., Gombosi, T.I.!!!, . (2014) "Magnetospheric Structure and Atmospheric Joule Heating of Habitable Planets Orbiting M-dwarf Stars," The Astrophysical Journal 790: pp. 57

Selected Presentations

  • - NASA’s Heliophysics summer school, July 2014 - Boulder CO
  • - Physics colloquium, April 2014
  • - Space Science colloquium, October 2013 - Durham, NH
  • - ESS Colloquium, April 2013
  • - Physics Colloquium, February 2013
  • - Heliophysics division seminar, November 2012
  • - LPL colloquium, October 2012
  • - Astrophysics Seminar, May 2010 - Rehovot, Israel
  • - Dep. Of Geophysics seminar, May 2010 - Tel-Aviv, Israel
  • - Physics Colloquium and Space Physics seminar, January 2010
  • - Solar Stellar & Planetary Astrophysics Division weekly seminar, October 2009 - Cambridge, MA
  • - Theoretical Astrophysics Division luncheon, October 2009 - Cambridge, MA
  • - High Energy Division weekly seminar, October 2008
  • - Astrophysics seminar, June 2008 - Beer-Sheva, Israel

Selected Contracts, Fellowships, Grants and Sponsored Research

  • Geophysically Relevant Prediction of Solar Cycle 25 (2016), Grant -
    Cohen, O.
  • The Heliosphere in Time: Scaling Heliospheric Parameters with Stellar Evolution of Solar Analogs and Studying Heliospheric Consequences of Young Active Suns (2016), Grant - NASA LWS
    Cohen, O. (Principal)
  • The Living, Breathing Planet (2015), Grant - NASA NEXSS
    Cohen, O.
  • Can Exoplanets Around Red Dwarfs Maintain Habitable Atmospheres? (2014), Grant - SI Competitive Grants Program for Science
    Cohen, O. (Co-Principal), Drake, J. (Principal)
  • Lessons from Mars: Are Habitable Atmospheres on Planets around M Dwarfs Viable? (2014), Grant - The Smithsonian Consortia
    Cohen, O. (Co-Principal), Drake, J.
  • 3D MHD Modeling of Stellar Coronae (2012), Grant - Chandra theory program cycle 13
    Cohen, O. (Principal)
  • The Faint Young sun Paradox (2012), Grant - The Smithsonian Consortia
    Cohen, O. (Co-Principal), Latham, D. (Principal)
  • Life and the Cosmos: Building the Consortium (2011), Grant - The Smithsonian Consortia
    Cohen, O. (Co-Principal), Drake, J. (Principal)
  • The Role of Coronal Mass Ejections in Reversal the Open Magnetic Flux of the Sun (2008), Grant - National Science Foundation
    Cohen, O. (Principal)