Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star
Artikel i vetenskaplig tidskrift, 2015

We report the spectroscopic confirmation of the Kepler object of interest KOI-183.01 (Kepler-423b), a half-Jupiter mass planet transiting an old solar-like star every 2.7 days. Our analysis is the first to combine the full Kepler photometry (quarters 1 17) with high-precision radial velocity measurements taken with the FIES spectrograph at the Nordic Optical Telescope. We simultaneously modelled the photometric and spectroscopic data-sets using Bayesian approach coupled with Markov chain Monte Carlo sampling. We found that the Kepler pre-search data conditioned light curve of Kepler-423 exhibits quarter-to-quarter systematic variations of the transit depth, with a peak-to-peak amplitude of similar to 4.3% and seasonal trends reoccurring every four quarters. We attributed these systematics to an incorrect assessment of the quarterly variation of the crowding metric. The host star Kepler-423 is a G4 dwarf with M-* = 0.85 +/- 0.04 M-circle dot, R-* = 0.95 +/- 0.04 R-circle dot, T-eff = 5560 +/- 80 K, [M/H] = -0.10 +/- 0.05 dex, and with an age of 11 +/- 2 Gyr. The planet Kepler-423b has a mass of M-p = 0.595 +/- 0.081 M-Jup and a radius of R-p = 1.192 +/- 0.052 R-Jup, yielding a planetary bulk density of rho(p) = 0.459 +/- 0.083 g cm(-3). The radius of Kepler-423b is consistent with both theoretical models for irradiated coreless giant planets and expectations based on empirical laws. The inclination of the stellar spin axis suggests that the system is aligned along the line of sight. We detected a tentative secondary eclipse of the planet at a 2 sigma confidence level (Delta F-ec = 14.2 +/- 6.6 ppm) and found that the orbit might have a small non-zero eccentricity of 0.019(-0.014)(+0.028) . With a Bond albedo of A(B) = 0.037 +/- 0.019, Kepler-423b is one of the gas-giant planets with the lowest albedo known so far.

stars: fundamental parameters

planets and satellites: detection

planets and satellites: individual: Kepler-423b

techniques: photometric

techniques: radial velocities

planets and satellites: fundamental parameters

Författare

D. Gandolfi

Osservatorio Astrofisico di Catania

Landessternwarte Heidelberg

H. Parviainen

University of Oxford

H. J. Deeg

Instituto Astrofisico de Canarias

Universidad de la Laguna

A. F. Lanza

Osservatorio Astrofisico di Catania

Malcolm Fridlund

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

P. G. P. Moroni

Universita di Pisa

R. Alonso

Universidad de la Laguna

Instituto Astrofisico de Canarias

T. Augusteijn

J. Cabrera

Deutsches Zentrum fur Luft- Und Raumfahrt

T. Evans

University of Oxford

S. Geier

A. Hatzes

T. Holczer

Tel Aviv University

S. Hoyer

Universidad de la Laguna

Instituto Astrofisico de Canarias

T. Kangas

Tuorla Observatory

T. Mazeh

Tel Aviv University

I. Pagano

Osservatorio Astrofisico di Catania

L. Tal-Or

Tel Aviv University

B. Tingley

Aarhus Universitet

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 576

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201425062