Estimating transiting exoplanet masses from precise optical photometry

D. Mislis, R. Heller, J. H.M.M. Schmitt, S. Hodgkin

Research output: Contribution to journalArticle

22 Citations (Scopus)


We present a theoretical analysis of the optical light curves (LCs) for short-period high-mass transiting extrasolar planet systems. Our method considers the primary transit, the secondary eclipse, and the overall phase shape of the LC between the occultations. Phase variations arise from (i) reflected and thermally emitted light by the planet; (ii) the ellipsoidal shape of the star due to the gravitational pull of the planet; and (iii) the Doppler shift of the stellar light as the star orbits the center of mass of the system. Our full model of the out-of-eclipse variations contains information about the planetary mass, orbital eccentricity, the orientation of periastron and the planet's albedo. For a range of hypothetical systems we demonstrate that the ellipsoidal variations (ii) can be large enough to be distinguished from the remaining components and that this effect can be used to constrain the planet's mass. To detect the ellipsoidal variations, the LC requires a minimum precision of 10 -4, which coincides with the precision of the Kepler mission. As a test of our approach, we consider the Kepler LC of the transiting object HAT-P-7. We are able to estimate the mass of the companion, and confirm its planetary nature solely from the LC data. Future space missions, such as PLATO and the James Webb Space Telescope with even higher photometric precision, will be able to reduce the errors in all parameters. Detailed modeling of any out-of-eclipse variations seen in new systems will be a useful diagnostic tool prior to the requisite ground based radial velocity follow-up.

Original languageEnglish
Article numberA4
JournalAstronomy and Astrophysics
Publication statusPublished - 30 Jan 2012



  • celestial mechanics
  • methods: analytical
  • methods: data analysis
  • planetary systems
  • techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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