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Title: A POSSIBLE CARBON-RICH INTERIOR IN SUPER-EARTH 55 Cancri e

Abstract

Terrestrial planets in the solar system, such as the Earth, are oxygen-rich, with silicates and iron being the most common minerals in their interiors. However, the true chemical diversity of rocky planets orbiting other stars is yet unknown. Mass and radius measurements are used to constrain the interior compositions of super-Earths (exoplanets with masses of 1-10 M{sub Circled-Plus }), and are typically interpreted with planetary interior models that assume Earth-centric oxygen-rich compositions. Using such models, the super-Earth 55 Cancri e (mass 8 M{sub Circled-Plus }, radius 2 R{sub Circled-Plus }) has been suggested to bear an interior composition consisting of Fe, silicates, and an envelope ({approx}> 10% by mass) of supercritical water. We report that the mass and radius of 55 Cancri e can also be explained by a carbon-rich solid interior made of Fe, C, SiC, and/or silicates and without a volatile envelope. While the data allow Fe mass fractions of up to 40%, a wide range of C, SiC, and/or silicate mass fractions are possible. A carbon-rich 55 Cancri e is also plausible if its protoplanetary disk bore the same composition as its host star, which has been reported to be carbon-rich. However, more precise estimates of themore » stellar elemental abundances and observations of the planetary atmosphere are required to further constrain its interior composition. The possibility of a C-rich interior in 55 Cancri e opens a new regime of geochemistry and geophysics in extraterrestrial rocky planets, compared to terrestrial planets in the solar system.« less

Authors:
 [1];  [2];  [3]
  1. Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06511 (United States)
  2. Department of Geology and Geophysics, Yale University, New Haven, CT 06511 (United States)
  3. Universite de Franche-Comte, Institut UTINAM, CNRS/INSU, UMR 6213, Observatoire des Sciences de l'Univers THETA, CP 1615, F-25010 Besancon Cedex (France)
Publication Date:
OSTI Identifier:
22078440
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 759; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CARBON; GEOCHEMISTRY; GEOPHYSICS; IRON; MASS; OXYGEN; PLANETARY ATMOSPHERES; PLANETS; PROTOPLANETS; SILICATES; SILICON CARBIDES; SOLAR SYSTEM; STARS; WATER

Citation Formats

Madhusudhan, Nikku, Lee, Kanani K. M., and Mousis, Olivier, E-mail: Nikku.Madhusudhan@yale.edu. A POSSIBLE CARBON-RICH INTERIOR IN SUPER-EARTH 55 Cancri e. United States: N. p., 2012. Web. doi:10.1088/2041-8205/759/2/L40.
Madhusudhan, Nikku, Lee, Kanani K. M., & Mousis, Olivier, E-mail: Nikku.Madhusudhan@yale.edu. A POSSIBLE CARBON-RICH INTERIOR IN SUPER-EARTH 55 Cancri e. United States. doi:10.1088/2041-8205/759/2/L40.
Madhusudhan, Nikku, Lee, Kanani K. M., and Mousis, Olivier, E-mail: Nikku.Madhusudhan@yale.edu. Sat . "A POSSIBLE CARBON-RICH INTERIOR IN SUPER-EARTH 55 Cancri e". United States. doi:10.1088/2041-8205/759/2/L40.
@article{osti_22078440,
title = {A POSSIBLE CARBON-RICH INTERIOR IN SUPER-EARTH 55 Cancri e},
author = {Madhusudhan, Nikku and Lee, Kanani K. M. and Mousis, Olivier, E-mail: Nikku.Madhusudhan@yale.edu},
abstractNote = {Terrestrial planets in the solar system, such as the Earth, are oxygen-rich, with silicates and iron being the most common minerals in their interiors. However, the true chemical diversity of rocky planets orbiting other stars is yet unknown. Mass and radius measurements are used to constrain the interior compositions of super-Earths (exoplanets with masses of 1-10 M{sub Circled-Plus }), and are typically interpreted with planetary interior models that assume Earth-centric oxygen-rich compositions. Using such models, the super-Earth 55 Cancri e (mass 8 M{sub Circled-Plus }, radius 2 R{sub Circled-Plus }) has been suggested to bear an interior composition consisting of Fe, silicates, and an envelope ({approx}> 10% by mass) of supercritical water. We report that the mass and radius of 55 Cancri e can also be explained by a carbon-rich solid interior made of Fe, C, SiC, and/or silicates and without a volatile envelope. While the data allow Fe mass fractions of up to 40%, a wide range of C, SiC, and/or silicate mass fractions are possible. A carbon-rich 55 Cancri e is also plausible if its protoplanetary disk bore the same composition as its host star, which has been reported to be carbon-rich. However, more precise estimates of the stellar elemental abundances and observations of the planetary atmosphere are required to further constrain its interior composition. The possibility of a C-rich interior in 55 Cancri e opens a new regime of geochemistry and geophysics in extraterrestrial rocky planets, compared to terrestrial planets in the solar system.},
doi = {10.1088/2041-8205/759/2/L40},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 759,
place = {United States},
year = {2012},
month = {11}
}