Abstract Details

Title: Finding habitable earths around white dwarfs with a robotic telescope transit survey

Authors: Eric Agol

Institute/Affiliation: University of Washington

Abstract Type: talk

Abstract Information:

To date the search for habitable Earth-like planets has primarily focused on nuclear burning stars. I propose that this search should be expanded to cool white dwarf stars that have expended their nuclear fuel. I define the continuously habitable zone of white dwarfs, and show that it extends from about 0.005 to 0.02 AU for white dwarfs with masses from 0.4-0.9 solar masses, temperatures less than 10,000 K, and habitable durations of at least 3 Gyr. As they are similar in size to Earth, white dwarfs may be completely eclipsed by terrestrial planets that orbit edge-on, which can easily be detected with ground-based telescopes. If planets can migrate inward or reform near white dwarfs, I show that a global robotic telescope network could carry out a transit survey of nearby white dwarfs placing interesting constraints on the presence of habitable Earths. If planets were detected, I show that the survey would favor detection of planets similar to Earth: similar size, temperature, and rotation period. The host stars of such planets would appear similar to the Sun for an observer on the planet surface. The Large Synoptic Survey Telescope (LSST) could place even tighter constraints on the frequency of habitable Earths around white dwarfs for a cost that is much less than space telescope searches around nuclear burning stars. The confirmation and characterization of these planets, if found close enough to us, might be carried out with the next generation of large ground and space telescopes.