paper

KOI-3278: A Self-Lensing Binary Star System

arXiv:1404.4379 · doi:10.1126/science.1251999

Abstract

Over 40% of Sun-like stars are bound in binary or multistar systems. Stellar remnants in edge-on binary systems can gravitationally magnify their companions, as predicted 40 years ago. By using data from the Kepler spacecraft, we report the detection of such a "self-lensing" system, in which a 5-hour pulse of 0.1% amplitude occurs every orbital period. The white dwarf stellar remnant and its Sun-like companion orbit one another every 88.18 days, a long period for a white dwarf-eclipsing binary. By modeling the pulse as gravitational magnification (microlensing) along with Kepler's laws and stellar models, we constrain the mass of the white dwarf to be ~63% of the mass of our Sun. Further study of this system, and any others discovered like it, will help to constrain the physics of white dwarfs and binary star evolution.

Published in Science. Main text 6 pages, 3 figures. Supplement 16 pages, 7 figures. Code used for analysis is available at http://github.com/ethankruse/koi3278 . Animation showing ingress of the lensing event at https://www.dropbox.com/s/eb3pznxi990vn00/KOI3278_pulse_starspots2_1024.mp4 . Executive summary for non-astronomers available at http://www.astro.washington.edu/users/eakruse/papers.php

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