Gregory A. Feiden




Research Summary

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My primary interests lie in stellar evolution theory, which is a very broad and all-encompassing field of stellar astrophysics. Specifically, I work with stellar evolution models—a computational realization of the mathematical theory—that numerically implements a vast array of physics to simulate the interior conditions of stars. The main goal of stellar evolution models is to understand in detail what physical processes contribute to the observed properties of stars. That means models tie observable properties of stars (i.e., photometry and spectoscopy) to the fundamental properties of the stars that produce those observables (i.e., mass, radius, temperature). However, the validity of the “transformation” from observables to fundamental properties (and vice versa) requires that the model physics be accurate (meaning correct). That is where my research comes into the picture: I enjoy testing and modifying the current physics as well as adding new physics, when necessary.

Recently, this endeavor has taken the form of stuyding low-mass—taken to be stars with mass approximately equal to, or less than, that of the Sun—in detached eclipsing binary systems. The stars in these systems have been discovered to be upward of 10% larger than what stellar evolution models predict. It is thought that stellar magnetic fields may be the cause of this observed discrepancy. However, there are no stellar models that account for the effects of stellar magnetism in a self-consistent fashion. As you can probably guess, I've taken up the challenge. For more information on low-mass stars, detached ecipsing binaries, stellar magnetic fields, stellar evolution models, and the intersection of all four concepts, please visit this detailed research page or check out the publications below.


Refereed Publications

  1. Feiden, G. A. & Chaboyer, B. (2013) Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars with a Radiative Core, ApJ, 779, 1.

  2. Feiden, G. A. & Dotter, A. (2013) The Interior Structure Constants as an Age Diagnostic for Low-Mass, Pre-Main Sequence Detached Eclipsing Binary Stars, ApJ, 765, 86.

  3. Feiden, G. A. & Chaboyer, B. (2012) Self-Consistent Stellar Evolution Models of the Detached, Solar-Type Eclipsing Binary EF Aquarii, ApJ, 761, 30.

  4. Terrien, R. C.; Fleming, S. W.; Mahadevan, S.; Deshpande, R.; Feiden, G. A.; Bender, C. F.; & Ramsey, L. W. (2012), The Metallicity of the CM Draconis System, ApJL, 760, L9.

  5. Feiden, G. A. & Chaboyer, B. (2012) Reevaluating the Mass-Radius Relation for Low-Mass, Main Sequence Stars, ApJ, 757, 42.

  6. Brogaard, K.; VandenBerg, D. A.; Bruntt, H.; Grundahl, F.; Frandsen, S.; Bedin, L. R.; Milone, A. P.; Dotter, A.; Feiden, G. A.; Stetson, P. B.; Sandquist, E.; Miglio, A.; Stello, D.; & Jessen-Hansen, J. (2012) Age and helium content of the open cluster NGC 6791 from multiple eclipsing binary members II. age dependencies and new insights, A&A, 543, A106.

  7. Feiden, G. A.; Chaboyer, B.; & Dotter, A. (2011) Accurate Low-Mass Stellar Models of KOI-126, ApJL, 739, L25.

  8. Kanbur, S.; Ngeow, C.-C.; & Feiden, G. A. (2007) Period-colour and amplitude-colour relations in classical Cepheid variables - V. The Small Magellanic Cloud Cepheid models, MNRAS, 380, 819.

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Talks

  1. Do Magnetic Fields Actually Inflate Low-Mass Stars?, Binary 2013: Setting a new standard in the analysis of binary stars, Leuven, Belgium, 17 September 2013.

  2. Do Magnetic Fields Actually Inflate Low-Mass Stars?, IAU Symposium #302: Magnetic Fields Throughout Stellar Evolution, Biarritz, France, 26 August 2013.

  3. Can Magnetic Fields Inflate Low-Mass Stars?, Science Today Colloquium, SUNY Oswego, Oswego, NY, 06 February 2013.

  4. Self-Consistent Magnetic Stellar Evolution Models of Low-Mass Stars in Detached Eclipsing Binaries, Dissertation Presentation — AAS Meeting 221, Long Beach, California, USA, 08 January 2013.

  5. 1-D Magnetic Stellar Evolution Models of Low-Mass Stars, Astrophysics group seminar, NORDITA, Stockholm, Sweden, 19 December 2012.

  6. Self-Consistent Magnetic Stellar Evolution Models, Astronomy seminar, Uppsala Universitet, Uppsala, Sweden, 13 September 2012.