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I'm a third year graduate student and NSF Research Fellow, conducting research primarily on extrasolar planets and eclipsing binary stars. I also work part-time as an observing specialist for the 3.5-meter telescope at Apache Point, and assist with the operations of NMSU's robotic 1-meter telescope.
Please go to my homepage for information on my research, teaching, publications, and access to IRAF scripts and C++ code I've made available.
Research
Transiting Extrasolar Planets
I have previously studied parameter variations in transiting systems in order to probe for lower mass, possibly Earth-sized planets in those systems. I am currently working on disentangling the effects of limb darkening and atmospheric absorption versus wavelength in order to use ground-based transit data to probe the atmospheric properties of transiting extrasolar planets. I have been working with Dr. Thomas Harrison on a new high-speed photometer that will simultaneously gather observations at 6 different wavelengths, newley installed on the NMSU 1-meter telescope. This are will be the principal focus of my thesis.
Low-Mass Eclipsing Binaries
Observations by currently known low-mass eclipsing binaries (LMB's), of which less than 20 are known, indicate that low-mass stars have radii that are about 10% greater than predicted by current models. Theories for this discrepency include enhanced metallicity, age effects, and enhanced magnetic activity due to enhanced rotation rates, with the latter being the most likely scenario. To test these theories, I have worked on discovering new LMB's, obtaining light and radial-velocity curves, and modeling them to obtain accurate mass and radius measurements. I have obtained time on the recently launched Kepler spacecraft to stare at 1,200 K and M dwarf stars to search for and obtain precise light curves of long-period (P > 10 days) LMB's, where the orbital rate begins to match the natural rotation rates of these stars.
Multi-Wavelength Modeling of Binary Systems as Seen by the Space Interferometry Mission (SIM)
The Space Interferometry Mission (SIM) is a proposed spacecraft that will be capable of obtaining postions of stars to a precision of 1 microarcsecond. The principal scientific mission is to search for Earth-like planets, however time will be set aside for additional scientific targets, namely observations of binary star systems. I am modeling how varying systems' reflex motions will vary versus wavelength as seen by the SIM spacecraft. With multi-wavelength SIM observations, I have determined it will be possible to obtain individual orbits of both stars in a given binary system, thus yielding absolute masses, inclinations, and luminosity ratios. Also, through SIM we will be able to probe starspot cycles on stars in single and binary systems, and even determine absolute inclinations for single stars.
Near Contact and W Uma Stars and Thier Formation
I have studied many near-contact and contact eclipsing binary systems, and am interested in thier evolutionary history and general theories of formation. It is now known that W Uma stars are old systems that have gone through a complicated cycle of mass-transfer and stellar evolution, but many of the details are missing. Although this was work I principally did while in undergrad and my first year in graduate school, it is a subject that I hope to return to one day.
Support
I'm pleased to acknowledge support from a NSF Graduate Research Fellowship, the Kepler Guest Observer Program, the Astrophysical Research Consortium, and the New Mexico Space Grant Consortium.
Papers
Orbital Solutions and Absolute Elements of the Eclipsing Binary MY Cygni
Tucker, R.S., Sowell, J.R., Williamon, R.M., & Coughlin, J.L. 2009, AJ, 137, 2949.
New Observations and a Possible Detection of Parameter Variations in the Transits of Gliese 436b
Coughlin, J.L., Stringfellow, G., Becker, A., López-Morales, M., Mezzalira, F., & Krajci, T. 2008, ApJL, 689, 149
Long-term Photometric Analysis of the Active W Uma-type System TU Boo
Coughlin, J.L., Dale, H.A., & Williamon, R.M. 2008, AJ, 136, 1089
New β Lyrae and Algol Candidates from the Northern Sky Variability Survey
Hoffman, D.I., Harrison, T.E., Coughlin, J.L., et al. 2008, AJ, 136, 1067
Seven New Low-Mass Eclipsing Binaries
Coughlin, J.L. and Shaw, J.S. 2007, SARA, 1, 7C
Observations and Models of Eclipsing Binary Stars
Coughlin, J.L. 2007, Undergraduate Thesis, Emory University
Meetings & Posters
March 2009: The 14th North American Workshop on Cataclysmic Variables and Related Objects
Observing Stellar Binaries with SIM Lite
T. Harrison & J.L. Coughlin
Janurary 2009: American Astronomical Society Meeting
Parameter Variations in the Transits of Gliese 436b
J. Coughlin, G. Stringfellow, A. Becker, M. López-Morales, T. Krajci, F. Mezzalira, & E. Algol
July 2008: Cool Stars XV
Transit Timing Observations of the Extrasolar Hot-Neptune Planet GL436b
G. Stringfellow, J. Coughlin, M. Lopez-Morales, A. Becker, T. Krajci, F. Mezzalira, & E. Algol
January 2008: American Astronomical Society Meeting
Long-term Photometric Analysis of the Active W UMa-type System TU Bootis
J.L. Coughlin, H. Dale, & R.M. Williamon
January 2007: American Astronomical Society Meeting
Five New Low-Mass Eclipsing Binary Systems
J.L. Coughlin, M. López-Morales, & J.S. Shaw
November 2006: 14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
Six New Low-Mass Eclipsing Binaries below One Solar Mass
M. López-Morales, J.S. Shaw, & J.L. Coughlin
Talks
April 2009: New Mexico State University Graduate Research and Arts Symposium
Discovering and Characterizing Transiting Extrsolar Planets
April 2009: University of New Mexico Graduate Research Symposium
Transiting Extrasolar Planets
October 2008: National Radio Astronomy Observatory 24th Annual New Mexico Symposium
Possible detection of a several-earth-mass planet via orbital perturbations in the Gliese 436 system
September 2008: New Mexico State University Pizza Lunch Series
Possible Detection of an 8 Earth Mass Planet via Orbital Perturbations in the Gliese 436 System
February 2008: Penn State Astronomy Club
Extrasolar Planets, Moon Lasers, and Other Adventures in Astronomy