K2-139 b: A low-mass warm Jupiter on a 29-d orbit transiting an active K0 V star
This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record Barragán, O. et al. "K2-139 b: A low-mass warm Jupiter on a 29-d orbit transiting an active K0 V star" is available online at: http://doi.org/10.1093/mnras/stx3207 ; We announce the discovery of K2-139 b (EPIC 218916923 b), a transiting warm-Jupiter (Teq= 547± 25 K) on a 29-d orbit around an active (logR'HK=-4.46±0.06) K0V star in K2 Campaign 7.We derive the system's parameters by combining the K2 photometry with groundbased follow-up observations. With a mass of 0.387-0.033+0.075MJand radius of 0.808-0.033+0.034RJ, K2-139 b is one of the transiting warm Jupiters with the lowest mass known to date. The planetary mean density of 0.91-0.20+0.24g cm-3can be explained with a core of ~50M⊕. Given the brightness of the host star (V=11.653 mag), the relatively short transit duration (~5 h), and the expected amplitude of the Rossiter-McLaughlin effect (~25m s-1), K2-139 is an ideal target to measure the spin-orbit angle of a planetary system hosting a warm Jupiter ; D. Gandolfi gratefully acknowledges the financial support of the Programma Giovani Ricercatori – Rita Levi Montalcini – Rientro dei Cervelli (2012) awarded by the Italian Ministry of Education, Universities and Research (MIUR). Sz. Csizmadia thanks the Hungarian OTKA Grant K113117. H. J. Deeg and D. Nespral acknowledge support by grant ESP2015-65712-C5-4-R of the Spanish Secretary of State for R& D&i (MINECO). D. Lorenzo-Oliveira acknowledges the support from FAPESP (2016/20667-8). This research was supported by the Ministerio de Economia y Competitividad under project FIS2012-31079. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2013-2016) under grant agreement No. 312430 (OPTICON).