3,490 research outputs found
The Metallicities of Stars With and Without Transiting Planets
Host star metallicities have been used to infer observational constraints on
planet formation throughout the history of the exoplanet field. The giant
planet metallicity correlation has now been widely accepted, but questions
remain as to whether the metallicity correlation extends to the small
terrestrial-sized planets. Here, we report metallicities for a sample of 518
stars in the Kepler field that have no detected transiting planets and compare
their metallicity distribution to a sample of stars that hosts small planets
(Rp < 1.7 R_Earth). Importantly, both samples have been analyzed in a
homogeneous manner using the same set of tools (Stellar Parameters
Classification tool; SPC). We find the average metallicity of the sample of
stars without detected transiting planets to be [m/H]_SNTP,dwarf = -0.02 +-
0.02 dex and the sample of stars hosting small planets to be [m/H]_STP = -0.02
+- 0.02 dex. The average metallicities of the two samples are indistinguishable
within the uncertainties, and the two-sample Kolmogorov-Smirnov test yields a
p-value of 0.68 (0.41 sigma), indicating a failure to reject the null
hypothesis that the two samples are drawn from the same parent population. We
conclude that the homogeneous analysis of the data presented here support the
hypothesis that stars hosting small planets have a metallicity similar to stars
with no known transiting planets in the same area of the sky.Comment: Accepted for publication in Ap
Detection of Planetary Transits Across a Sun-like Star
We report high precision, high cadence photometric measurements of the star
HD 209458, which is known from radial velocity measurements to have a planetary
mass companion in a close orbit. We detect two separate transit events at times
that are consistent with the radial velocity measurements. In both cases, the
detailed shape of the transit curve due to both the limb darkening of the star
and the finite size of the planet is clearly evident. Assuming stellar
parameters of 1.1 R_Sun and 1.1 M_Sun, we find that the data are best
interpreted as a gas giant with a radius of 1.27 +/- 0.02 R_Jup in an orbit
with an inclination of 87.1 +/- 0.2 degrees. We present values for the
planetary surface gravity, escape velocity, and average density, and discuss
the numerous observations that are warranted now that a planet is known to
transit the disk of its parent star.Comment: 10 pages, 3 figures, accepted by ApJ Letter
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