Research

I work on a variety of projects related to low-mass stars and extrasolar planets.  M dwarfs are small stars; they are less than half the mass of the sun and less than half the diameter.  They are the most common stars in the Universe, but you can't see any of them with the naked eye because they are faint.  Despite being so common, they are poorly understood in many ways: we have trouble determining their true sizes (and the sizes of exoplanets found to orbit them) and we don't really know if they can host habitable, Earth-like planets.  I am researching novel methods to accurately determine the masses, sizes and luminosities of these interesting stars.

I also like to build instruments for telescopes that measure light from stars in new, unique ways.  My involvement in astronomical instruments has led me into new areas of research including studies of white dwarfs, nova, supernova and outbursting pre-main sequence stars.  See the Papers and Abstracts section for details.

Below I list some specific scientific results and projects of mine with links to papers and press releases:

Small Stars with Small Planets (or White Dwarfs):

KOI-256 - Using gravitational lensing in an eclipsing post-common envelope binary to measure accurate M dwarf/white dwarf masses, radii and temperatures.  Here is a NASA press release about this study with a great video by IPAC's Dr. Robert Hurt:

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KOI-961 (now Kepler 42) - A small star with 3 sub-Earth-sized planets!  Here is a news article in Nature
about this study.

Distilling Nearby M-Dwarfs for Terrestrial Exoplanets - A new Keck-HIRES Radial Velocity Planet Search.  Uses new methods for measuring M dwarf metallicities, developed by Bárbara Rojas-Ayala

Characterizing the Cool KOIs - Identifying compelling Kepler planet-candidates that orbit cool stars (aka Cool KOIs) with Katherine Hamren, Everett Schlawin, Bárbara Rojas-Ayala, Kevin Covey and James Lloyd.  Here's a talk I gave about this work at the First Kepler Science Conference, and a news article in Science Magazine.


Instrumentation:

LAEDI - A technique to measure ultra-precise stellar radial velocities with Gautam Vasisht and J. Kent Wallace (JPL).
 

Project Minerva - High-cadence radial velocity monitoring of nearby Stars with John Johnson and Co

TEDI - Precision radial velocities in the near-infrared
with Jerry Edelstein, David Erskine, Matthew Muterspaugh and James Lloyd

Mass-producing efficient NIR spectrographs with the TripleSpec Collaboration (Cornell/Caltech/UVA/Toronto)

Infrared interferometric imaging led by John Monnier

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