Characterizing Long-Period Transiting Planets Observed by Kepler

TL;DR

This paper demonstrates that combining Kepler photometry of long-period transiting planets with follow-up radial velocity measurements allows for accurate estimation of their periods and masses, even for planets with periods longer than the mission duration.

Contribution

It introduces a method to estimate the periods and masses of long-period transiting planets using combined photometry and radial velocity data, assuming circular orbits.

Findings

Periods can be estimated within 20% for planets larger than Neptune.

Masses can be estimated within a factor of 2 for planets similar or larger than Jupiter.

Eccentricity impacts the accuracy of parameter estimates.

Abstract

Kepler will monitor a sufficient number of stars that it is likely to detect single transits of planets with periods longer than the mission lifetime. We show that by combining the exquisite Kepler photometry of such transits with precise radial velocity observations taken over a reasonable timescale (~ 6 months) after the transits, and assuming circular orbits, it is possible to estimate the periods of these transiting planets to better than 20%, for planets with radii greater than that of Neptune, and the masses to within a factor of 2, for planets with masses larger than or about equal to the mass of Jupiter. Using a Fisher matrix analysis, we derive analytic estimates for the uncertainties in the velocity of the planet and the acceleration of the star at the time of transit, which we then use to derive the uncertainties for the planet mass, radius, period, semimajor axis, and orbital inclination. Finally, we explore the impact of orbital eccentricity on the estimates of these quantities.