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Title: A CORRELATION BETWEEN THE ECLIPSE DEPTHS OF KEPLER GAS GIANT CANDIDATES AND THE METALLICITIES OF THEIR PARENT STARS

Abstract

Previous studies of the interior structure of transiting exoplanets have shown that the heavy-element content of gas giants increases with host star metallicity. Since metal-poor planets are less dense and have larger radii than metal-rich planets of the same mass, one might expect that metal-poor stars host a higher proportion of gas giants with large radii than metal-rich stars. Here I present evidence for a negative correlation at the 2.3{sigma} level between eclipse depth and stellar metallicity in the Kepler gas giant candidates. Based on Kendall's {tau} statistics, the probability that eclipse depth depends on star metallicity is 0.981. The correlation is consistent with planets orbiting low-metallicity stars being, on average, larger in comparison with their host stars than planets orbiting metal-rich stars. Furthermore, since metal-rich stars have smaller radii than metal-poor stars of the same mass and age, a uniform population of planets should show a rise in median eclipse depth with [M/H]. The fact that I find the opposite trend indicates that substantial changes in the gas giant interior structure must accompany increasing [M/H]. I investigate whether the known scarcity of giant planets orbiting low-mass stars could masquerade as an eclipse depth-metallicity correlation, given the degeneracy between metallicitymore » and temperature for cool stars in the Kepler Input Catalog. While the eclipse depth-metallicity correlation is not yet on firm statistical footing and will require spectroscopic [Fe/H] measurements for validation, it is an intriguing window into how the interior structure of planets and even the planet formation mechanism may be changing with Galactic chemical evolution.« less

Authors:
 [1]
  1. Astronomy Department, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712 (United States)
Publication Date:
OSTI Identifier:
22037073
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 752; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; CORRELATIONS; ECLIPSE; GALACTIC EVOLUTION; HYDROGEN; IRON; MASS; PLANETS; SATELLITES; STARS; STATISTICS

Citation Formats

Dodson-Robinson, Sarah E., E-mail: sdr@astro.as.utexas.edu. A CORRELATION BETWEEN THE ECLIPSE DEPTHS OF KEPLER GAS GIANT CANDIDATES AND THE METALLICITIES OF THEIR PARENT STARS. United States: N. p., 2012. Web. doi:10.1088/0004-637X/752/1/72.
Dodson-Robinson, Sarah E., E-mail: sdr@astro.as.utexas.edu. A CORRELATION BETWEEN THE ECLIPSE DEPTHS OF KEPLER GAS GIANT CANDIDATES AND THE METALLICITIES OF THEIR PARENT STARS. United States. https://doi.org/10.1088/0004-637X/752/1/72
Dodson-Robinson, Sarah E., E-mail: sdr@astro.as.utexas.edu. 2012. "A CORRELATION BETWEEN THE ECLIPSE DEPTHS OF KEPLER GAS GIANT CANDIDATES AND THE METALLICITIES OF THEIR PARENT STARS". United States. https://doi.org/10.1088/0004-637X/752/1/72.
@article{osti_22037073,
title = {A CORRELATION BETWEEN THE ECLIPSE DEPTHS OF KEPLER GAS GIANT CANDIDATES AND THE METALLICITIES OF THEIR PARENT STARS},
author = {Dodson-Robinson, Sarah E., E-mail: sdr@astro.as.utexas.edu},
abstractNote = {Previous studies of the interior structure of transiting exoplanets have shown that the heavy-element content of gas giants increases with host star metallicity. Since metal-poor planets are less dense and have larger radii than metal-rich planets of the same mass, one might expect that metal-poor stars host a higher proportion of gas giants with large radii than metal-rich stars. Here I present evidence for a negative correlation at the 2.3{sigma} level between eclipse depth and stellar metallicity in the Kepler gas giant candidates. Based on Kendall's {tau} statistics, the probability that eclipse depth depends on star metallicity is 0.981. The correlation is consistent with planets orbiting low-metallicity stars being, on average, larger in comparison with their host stars than planets orbiting metal-rich stars. Furthermore, since metal-rich stars have smaller radii than metal-poor stars of the same mass and age, a uniform population of planets should show a rise in median eclipse depth with [M/H]. The fact that I find the opposite trend indicates that substantial changes in the gas giant interior structure must accompany increasing [M/H]. I investigate whether the known scarcity of giant planets orbiting low-mass stars could masquerade as an eclipse depth-metallicity correlation, given the degeneracy between metallicity and temperature for cool stars in the Kepler Input Catalog. While the eclipse depth-metallicity correlation is not yet on firm statistical footing and will require spectroscopic [Fe/H] measurements for validation, it is an intriguing window into how the interior structure of planets and even the planet formation mechanism may be changing with Galactic chemical evolution.},
doi = {10.1088/0004-637X/752/1/72},
url = {https://www.osti.gov/biblio/22037073}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 752,
place = {United States},
year = {Sun Jun 10 00:00:00 EDT 2012},
month = {Sun Jun 10 00:00:00 EDT 2012}
}