17,319 research outputs found
Understanding The Effects Of Stellar Multiplicity On The Derived Planet Radii From Transit Surveys: Implications for Kepler, K2, and TESS
We present a study on the effect of undetected stellar companions on the
derived planetary radii for the Kepler Objects of Interest (KOIs). The current
production of the KOI list assumes that the each KOI is a single star. Not
accounting for stellar multiplicity statistically biases the planets towards
smaller radii. The bias towards smaller radii depends on the properties of the
companion stars and whether the planets orbit the primary or the companion
stars. Defining a planetary radius correction factor , we find that if the
KOIs are assumed to be single, then, {\it on average}, the planetary radii may
be underestimated by a factor of . If typical
radial velocity and high resolution imaging observations are performed and no
companions are detected, this factor reduces to . The correction factor is dependent upon the primary
star properties and ranges from for A and F
stars to for K and M stars. For missions like
K2 and TESS where the stars may be closer than the stars in the Kepler target
sample, observational vetting (primary imaging) reduces the radius correction
factor to . Finally, we show that if the
stellar multiplicity rates are not accounted for correctly, occurrence rate
calculations for Earth-sized planets may overestimate the frequency of small
planets by as much as \%.Comment: 10 pages, 6 Figures, Accepted for publication in The Astrophysical
Journal (Fix typo in Equation 6 of original astroph submission; correction
also submitted to Journal
Statistical properties of exoplanets II. Metallicity, orbital parameters, and space velocities
In this article we present a detailed spectroscopic analysis of more than 50
extra-solar planet host stars. Stellar atmospheric parameters and metallicities
are derived using high resolution and high S/N spectra. The spectroscopy
results, added to the previous studies, imply that we have access to a large
and uniform sample of metallicities for about 80 planet hosts stars. We make
use of this sample to confirm the metal-rich nature of stars with planets, and
to show that the planetary frequency is rising as a function of the [Fe/H].
Furthermore, the source of this high metallicity is shown to have most probably
an ``primordial'' source, confirming previous results. The comparison of the
orbital properties (period and eccentricity) and minimum masses of the planets
with the stellar properties also reveal some emerging but still not significant
trends. These are discussed and some explanations are proposed. Finally, we
show that the planet host stars included in the CORALIE survey have similar
kinematical properties as the whole CORALIE volume-limited planet search
sample. Planet hosts simply seem to occupy the metal-rich envelope of this
latter population.Comment: 15 pages, 10 (eps) figures, Astronomy & Astrophysics, in pres
- β¦