The GAPS programme with HARPS-N at TNG IX. The multi-planet system KELT-6: Detection of the planet KELT-6 c and measurement of the Rossiter-McLaughlin effect for KELT-6 b

Damasso, M.; Esposito, M.; Nascimbeni, V.; Desidera, S.; Bonomo, A.S.; Bieryla, A.; Malavolta, L.; Biazzo, K.; Sozzetti, A.; Covino, E.; Latham, D.W.; Gandolfi, D.; Rainer, M.; Petrovich, C.; Collins, K.A.; Boccato, C.; Claudi, R.U.; Cosentino, R.; Gratton, R.; Lanza, A.F.; Maggio, A.; Micela, G.; Molinari, E.; Pagano, I.; Piotto, G.; Poretti, E.; Smareglia, R.; Di Fabrizio, L.; Giacobbe, P.; Gomez-Jimenez, M.; Murabito, S.; Molinaro, M.; Affer, L.; Barbieri, M.; Bedin, L.R.; Benatti, S.; Borsa, F.; Maldonado, J.; Mancini, L.; Scandariato, G.; Southworth, J.; Zanmar Sanchez, R.

Abstract

Aims. For more than 1.5 years we spectroscopically monitored the star KELT-6 (BD+31?2447), which is known to host the transiting hot-Saturn KELT-6?b, because a previously observed long-term trend in radial velocity time series suggested that there is an outer companion.

Methods. We collected a total of 93 new spectra with the HARPS-N and TRES spectrographs. A spectroscopic transit of KELT-6?b was observed with HARPS-N, and simultaneous photometry was obtained with the IAC-80 telescope.

Results. We proved the existence of an outer planet with a mininum mass Mpsin i = 3.71 ± 0.21 MJup and a moderately eccentric orbit (e = 0.21-0.036+0.039) of period P ~ 3.5 years. We improved the orbital solution of KELT-6?b and obtained the first measurement of the Rossiter-McLaughlin effect, showing that the planet has a likely circular, prograde, and slightly misaligned orbit with a projected spin-orbit angle of ? = -36 ± 11 degrees. We improved the KELT-6?b transit ephemeris from photometry and provide new measurements of the stellar parameters. KELT-6 appears as an interesting case for studying the formation and evolution of multi-planet systems.

Citation

Damasso, M., Esposito, M., Nascimbeni, V., Desidera, S., Bonomo, A., Bieryla, A., …Zanmar Sanchez, R. (2015). The GAPS programme with HARPS-N at TNG IX. The multi-planet system KELT-6: Detection of the planet KELT-6 c and measurement of the Rossiter-McLaughlin effect for KELT-6 b. Astronomy & Astrophysics, 581, Article L6. https://doi.org/10.1051/0004-6361/201526995

• Journal Article Type: Article
• Acceptance Date: Aug 25, 2015
• Online Publication Date: Sep 16, 2015
• Publication Date: 2015-09
• Journal: Astronomy & Astrophysics
• Print ISSN: 0004-6361
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 581
• Article Number: L6
• DOI: https://doi.org/10.1051/0004-6361/201526995
• Keywords: stars, KELT-6, planetary systems, radial velocities, photometric, astrophysics
• Publisher URL: http://dx.doi.org/10.1051/0004-6361/201526995