THE MASS OF CoRoT-7b

Journal Article · Sat Dec 10 00:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/743/1/75· OSTI ID:22004490

Hatzes, Artie P; Wuchterl, Guenther ^[1]; Fridlund, Malcolm; Gandolfi, Davide ^[2]; Nachmani, Gil; Mazeh, Tsevi ^[3]; Valencia, Diana ^[4]; Hebrard, Guillaume; Borde, Pascal ^[5]; Carone, Ludmila; Paetzold, Martin ^[6]; Udry, Stephane ^[7]; Bouchy, Francois ^[8]; Deleuil, Magali; Moutou, Claire; Barge, Pierre ^[9]; Deeg, Hans; Tingley, Brandon ^[10]; Dvorak, Rudolf ^[11]; Ferraz-Mello, Sylvio ^[12] ; others, and

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1. Thueringer Landessternwarte, D-07778 Tautenburg (Germany)
2. European Space Agency, ESTEC, SRE-SA, P.O. Box 299, NL-2200AG, Noordwijk (Netherlands)
3. School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv (Israel)
4. Observatoire de la Cote d'Azur, BP 4229, F-06304 Nice Cedex 4 (France)
5. Institut d'Astrophysique de Paris, UMR 7095 CNRS, Universite Pierre and Marie Curie, 98bis boulevard Arago, F-75014 Paris (France)
6. Rheinisches Institut fuer Umweltforschung, Universitaet zu Koeln, Abt. Planetenforschung, Aachener Str. 209, D-50931 Koeln (Germany)
7. Observatoire de l'Universite de Geneve, 51 chemin des Maillettes, 1290 Sauverny (Switzerland)
8. Observatoire de Haute Provence, F-04670 Saint Michel l'Observatoire (France)
9. Laboratoire d'Astrophysique de Marseille, CNRS and University of Provence, 38 rue Frederic Joliot-Curie, F-13388 Marseille Cedex 13 (France)
10. Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)
11. University of Vienna, Institute of Astronomy, Tuerkenschanzstr. 17, A-1180, Vienna (Austria)
12. IAG, University of Sao Paulo (Brazil)

The mass of CoRoT-7b, the first transiting super-Earth exoplanet, is still a subject of debate. A wide range of masses have been reported in the literature ranging from as high as 8 M{sub Circled-Plus} to as low as 2.3 M{sub Circled-Plus }. This range in mass is largely due to the activity level of the star that contributes a significant amount of radial velocity (RV) 'jitter' and how the various methods correct this jitter. Although most mass determinations give a density consistent with a rocky planet, the lower value permits a bulk composition that can be up to 50% water. We present an analysis of the CoRoT-7b RV measurements that uses very few and simple assumptions in treating the activity signal. By analyzing those RV data for which multiple measurements were made in a given night, we remove the activity related RV contribution without any a priori model. We argue that the contribution of activity to the final RV curve is negligible and that the K-amplitude due to the planet is well constrained. This yields a mass of 7.42 {+-} 1.21 M{sub Circled-Plus} and a mean density of {rho} = 10.4 {+-} 1.8 gm cm{sup -3}. CoRoT-7b is similar in mass and radius to the second rocky planet to be discovered, Kepler-10b, and within the errors they have identical bulk densities-they are virtual twins. These bulk densities lie close to the density-radius relationship for terrestrial planets similar to what is seen for Mercury. CoRoT-7b and Kepler-10b may have an internal structure more like Mercury than the Earth.

• OSTI ID: 22004490
• Journal Information: Astrophysical Journal, Vol. 743, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACTIVITY LEVELS
AMPLITUDES
BULK DENSITY
EARTH PLANET
MERCURY PLANET
RADIAL VELOCITY
STARS