A Class of Eccentric Binaries with Dynamic Tidal Distortions Discovered with Kepler

We have discovered a class of eccentric binary systems within the Kepler data archive that have dynamic tidal distortions and tidally-induced pulsations. Each has a uniquely shaped light curve that is characterized by periodic brightening or variability at time scales of 4-20 days, frequently accompanied by shorter period oscillations. We can explain the dominant features of the entire class with orbitally-varying tidal forces that occur in close, eccentric binary systems. The large variety of light curve shapes arises from viewing systems at different angles. This hypothesis is supported by spectroscopic radial velocity measurements for five systems, each showing evidence of being in an eccentric binary system. Prior to the discovery of these 17 new systems, only four stars, where KOI-54 is the best example, were known to have evidence of these dynamic tides and tidally-induced oscillations. We perform preliminary fits to the light curves and radial velocity data, present the overall properties of this class and discuss the work required to accurately model these systems.

First Results from the Swarms Survey. SDSS 1257+5428: A Nearby, Massive White Dwarf Binary with a Likely Neutron Star or Black Hole Companion

We present the first results from SWARMS (Sloan White dwArf Radial velocity data Mining Survey), an ongoing project to identify compact white dwarf (WD) binaries in the spectroscopic catalog of the Sloan Digital Sky Survey. The first object identified by SWARMS, SDSS 1257+5428, is a single-lined spectroscopic binary in a circular orbit with a period of 4.56 hr and a semiamplitude of 322.7+-6.3 km/s. From the spectrum and photometry, we estimate a WD mass of 0.92(+0.28,-0.32) Msun. Together with the orbital parameters of the binary, this implies that the unseen companion must be more massive than 1.62(+0.20,-0.25) Msun, and is in all likelihood either a neutron star or a black hole. At an estimated distance of 48(+10,-19) pc, this would be the closest known stellar remnant of a supernova explosion.

Spitzer Planet Limits around the Pulsating White Dwarf GD66

We present infrared observations in search of a planet around the white dwarf, GD66. Time-series photometry of GD66 shows a variation in the arrival time of stellar pulsations consistent with the presence of a planet with mass > 2.4Mj. Any such planet is too close to the star to be resolved, but the planets light can be directly detected as an excess flux at 4.5um. We observed GD66 with the two shorter wavelength channels of IRAC on Spitzer but did not find strong evidence of a companion, placing an upper limit of 5--7Mj on the mass of the companion, assuming an age of 1.2--1.7Gyr.