Mancini, L, Lillo-Box, J, Southworth, J, Borsato, L, Gandolfi, D, Ciceri, S, Barrado, D, Brahm, R and Henning, T (2016) Kepler-539: A young extrasolar system with two giant planets on wide orbits and in gravitational interaction. Astronomy & Astrophysics, 590.

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Abstract

We confirm the planetary nature of Kepler-539 b (aka Kepler object of interest K00372.01), a giant transiting exoplanet orbiting a solar-analogue G2 V star. The mass of Kepler-539 b was accurately derived thanks to a series of precise radial velocity measurements obtained with the CAFE spectrograph mounted on the CAHA 2.2-m telescope. A simultaneous fit of the radial-velocity data and Kepler photometry revealed that Kepler-539 b is a dense Jupiter-like planet with a mass of Mp = 0.97 ± 0.29 MJup and a radius of Rp = 0.747 ± 0.018 RJup, making a complete circular revolution around its parent star in 125.6 days. The semi-major axis of the orbit is roughly 0.5 au, implying that the planet is at ≈0.45 au from the habitable zone. By analysing the mid-transit times of the 12 transit events of Kepler-539 b recorded by the Kepler spacecraft, we found a clear modulated transit time variation (TTV), which is attributable to the presence of a planet c in a wider orbit. The few timings available do not allow us to precisely estimate the properties of Kepler-539 c and our analysis suggests that it has a mass between 1.2 and 3.6 MJup, revolving on a very eccentric orbit (0.4 <e ≤ 0.6) with a period larger than 1000 days. The high eccentricity of planet c is the probable cause of the TTV modulation of planet b. The analysis of the CAFE spectra revealed a relatively high photospheric lithium content, A(Li) = 2.48 ± 0.12 dex, which, together with both a gyrochronological and isochronal analysis, suggests that the parent star is relatively young.

Item Type: Article
Additional Information: © EDP Sciences, This is the final published version of the article Mancini, L. et al., 2016. Kepler-539: A young extrasolar system with two giant planets on wide orbits and in gravitational interaction. A&A, 590, p.A112. It first appeared online via EDP Sciences at http://dx.doi.org/10.1051/0004-6361/201526357 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: planetary systems, stars, fundamental parameters, individual, Kepler-539
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 01 Nov 2016 14:42
Last Modified: 12 Apr 2019 12:52
URI: http://eprints.keele.ac.uk/id/eprint/2397

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