My work focuses on detecting, confirming, and characterizing cool companions to hot stars -- both transiting exoplanets and single-lined eclipsing binaries. As part of the Kilodegree Extremely Little Telescope (KELT) survey, I reduce the survey data; operate the transiting planet candidate selection pipeline; and coordinate high-precision follow-up efforts for the northern half of the survey. In a related effort, I am working on precisely and accurately measuring masses and radii for single-lined eclipsing binaries with M dwarf companions.
Current Research Projects
I am working with Scott Gaudi and others to measure masses and radii for AFG-M binaries without invoking stellar models and isochrones. Until recently, double-lined eclipsing binaries have been the most accessible systems for which we can precisely and accurately measure stellar paremters; however, analysis of M-M binaries is especially challenging for several reasons, so relatively few M dwarfs are well-characterized. The few well-characterized M dwarfs, however, suggest that the stellar models are under-estimating the radius and over-estimating the effective temperature, and many causes have been invoked to explain these discrepancies. I am demonstrating that distance measurements to single-lined EBs breaks the mass and radius degeneracy for these systems, enabling me to measure model-independent masses and radii for M dwarfs in these binaries. Given that single-lined EBs are commonly found by ground-based transit surveys, I can increase the sample of exquisitely characterized low-mass stars significantly with this method.
With Scott Gaudi and Keivan Stassun, I am determining precise effective temperatures, bolometric fluxes, and angular diameters for over 1.6 million stars in the Tycho-2 catalog; I am also determining radii for the subset of these stars that have sufficiently precise parallaxes from the Gaia Data Release 1 catalog.
Previous Research Projects
I led the discovery of KELT-12b, a highly inflated hot Jupiter on a ~5-day orbital period around a star at the end of its main-sequence lifetime. I also examined radius inflation in hot Jupiters: while hot Jupiters receiving more than 2x10^8 erg/s/cm^2 flux from their host stars tend to have larger radii, I found that hot Jupiters around hot stars (stars with effective temperatures above the Kraft break at ~6,250K, where heat transport in the core switches from convective to radiative) are generically puffier regardless of insolation. However, there are few hot Jupiters around hot stars that receive low amounts of incident flux, so we need more such systems and a better accounting of systematics affecting the demographics of planets discovered by ground-based surveys before saying anything definitive.
With Scott Gaudi, I showed how a minimum mass Msin(i) of an exoplanet discovered via radial velocity, along with an assumed exoplanet mass distribution, changes the transit probability of that system. Based on simulated exoplanet mass distributions, I found that Earths and super-Earths have a posterior transit probability that is 50% larger than the prior transit probability, R*/a. Super-Jupiters also have a boosted posterior transit probability, and the magnitude of the increase depends on the "dryness" of the brown dwarf desert. Here is the ADS abstract. A short video summarizing parts of this paper can be found on YouTube.