Colloquium on 26 September 2013
A Thermometer for Goldilocks: Accurate Temperatures of Kepler M Dwarfs and Their Planets

Details

Title: A Thermometer for Goldilocks: Accurate Temperatures of Kepler M Dwarfs and Their Planets
Speaker: Eric Gaidos
Date: Thursday, 26 September 2013
Time: 16:00 - 17:00
Venue: SAAO Auditorium

Abstract

M dwarf stars are especially attractive targets in the search for Earth-like planets because small planets are easier to detect around such stars, and the “habitable zone” is closer to the star where planets are more readily detected. The Kepler mission has discovered Earth-size planets transiting M dwarfs, including some that may orbit in the habitable zone. But the properties of these stars, and hence those of their planets, are poorly constrained. We have refined the temperatures of nearby M dwarfs whose angular diameters have been measured by interferometry. We find excellent agreement between certain model spectra and the observed spectra of these stars and use “spectrothermometry” to estimate the temperatures of distant Kepler M dwarfs with a precision of 60K. We then apply model-independent empirical relations to estimate stellar radius, luminosity, and mass, and use these in turn to revise the radii and stellar irradiances of M dwarf planets. We find that a recent estimate of the occurrence of Earth-size planets in the habitable zone of M dwarfs may need to be revised downwards by a factor of four.

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