David M. Kipping, William R. Dunn, Jamie M. Jasinski, Varun P. Manthri
We present a novel method to determine eccentricity constraints of extrasolar
planets in systems with multiple transiting planets through photometry alone.
Our method is highly model independent, making no assumptions about the stellar
parameters and requiring no radial velocity, transit timing or occultation
events. Our technique exploits the fact the light curve derived stellar density
must be the same for all planets transiting a common star. Assuming a circular
orbit, the derived stellar density departs from the true value by a predictable
factor, Psi, which contains information on the eccentricity of the system. By
comparing multiple stellar densities, any differences must be due to
eccentricity and thus meaningful constraints can be placed in the absence of
any other information. The technique, dubbed "Multibody Asterodensity
Profiling" (MAP), is a new observable which can be used alone or in combination
with other observables, such as radial velocities and transit timing
variations. An eccentricity prior can also be included as desired. MAP is most
sensitive to the minimum pair-combined eccentricity e.g. (e1 + e2)[min].
Individual eccentricity constraints are less stringent but an empirical
eccentricity posterior is always derivable and is freely available from transit
photometry alone. We present a description of our technique using both analytic
and numerical implementations, followed by two example analyses on synthetic
photometry as a proof of principle. We point out that MAP has the potential to
constrain the eccentricity, and thus habitability, of Earth-like planets in the
absence of radial velocity data, which is likely for terrestrial-mass objects.
View original:
http://arxiv.org/abs/1112.2700
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