Transiting exoplanets from the CoRoT space mission . XIX. CoRoT-23b: a dense hot Jupiter on an eccentric orbit

Autor(en)

Daniel Rouan, Hannu Parviainen, Claire Moutou, Rudolf Dvorak

Abstrakt

We report the detection of CoRoT-23b, a hot Jupiter transiting in front of

its host star with a period of 3.6314 \pm 0.0001 days. This planet was

discovered thanks to photometric data secured with the CoRoT satellite,

combined with spectroscopic radial velocity (RV) measurements. A photometric

search for possible background eclipsing binaries conducted at CFHT and OGS

concluded with a very low risk of false positives. The usual techniques of

combining RV and transit data simultaneously were used to derive stellar and

planetary parameters. The planet has a mass of Mp = 2.8 \pm 0.3 MJup, a radius

of Rpl = 1.05 \pm 0.13 RJup, a density of \approx 3 g cm-3. RV data also

clearly reveal a non zero eccentricity of e = 0.16 \pm 0.02. The planet orbits

a mature G0 main sequence star of V =15.5 mag, with a mass M\star = 1.14 \pm

0.08 M\odot, a radius R\star = 1. 61 \pm 0.18 R\odot and quasi-solar

abundances. The age of the system is evaluated to be 7 Gyr, not far from the

transition to subgiant, in agreement with the rather large stellar radius. The

two features of a significant eccentricity of the orbit and of a fairly high

density are fairly uncommon for a hot Jupiter. The high density is, however,

consistent with a model of contraction of a planet at this mass, given the age

of the system. On the other hand, at such an age, circularization is expected

to be completed. In fact, we show that for this planetary mass and orbital

distance, any initial eccentricity should not totally vanish after 7 Gyr, as

long as the tidal quality factor Qp is more than a few 105, a value that is the

lower bound of the usually expected range. Even if Corot-23b features a density

and an eccentricity that are atypical of a hot Jupiter, it is thus not an

enigmatic object.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Université de recherche Paris Sciences et Lettres, Instituto de Astrofísica de Canarias (IAC), Université de Provence Aix-Marseille I

Journal

Astronomy & Astrophysics

Band

537

Anzahl der Seiten

7

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/201117916

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/1190440c-0e2a-4145-b22c-a4895d594998