Publication details

It Takes Two Planets in Resonance to Tango around K2-146

Authors	LAM Kristine W. F. KORTH Judith MASUDA Kento CSIZMADIA Szilard EIGMULLER Philipp KARI STEFANSSON Gumundur ENDL Michael ALBRECHT Simon ROBERTSON Paul LUQUE Rafael LIVINGSTON John H. HIRANO Teruyuki ALONSO SOBRINO Roi BARRAGAN Oscar CABRERA Juan CARLEO Ilaria CHAUSHEV Alexander COCHRAN William D. DAI Fei DE LEON Jerome DEEG Hans J. ERIKSON Anders ESPOSITO Massimiliano FRIDLUND Malcolm FUKUI Akihiko GANDOLFI Davide GEORGIEVA Iskra GONZALEZ CUESTA Luca GRZIWA Sascha GUENTHER Eike W. HATZES Artie P. HIDALGO Diego HJORTH Maria KABATH Petr KNUDSTRUP Emil LUND Mikkel N. MAHADEVAN Suvrath MATHUR Savita MONTANES RODRIGUEZ Pilar MURGAS Felipe NARITA Norio NESPRAL David NIRAULA Prajwal PALLE Enric PATZOLD Martin PERSSON Carina M. PRIETO-ARRANZ Jorge RAUER Heike REDFIELD Seth RIBAS Ignasi SKARKA Marek SMITH Alexis M. S. SUBJAK Jan VAN EYLEN Vincent
Year of publication	2020
Type	Article in Periodical
Magazine / Source	Astronomical Journal
MU Faculty or unit	Faculty of Science
Citation
Web	https://doi.org/10.3847/1538-3881/ab66c9
Doi	http://dx.doi.org/10.3847/1538-3881/ab66c9
Keywords	Exoplanet astronomy; Transit photometry; Timing variation methods; Mini Neptunes; Exoplanet systems; Photometry; Astrometric exoplanet detection; Transit timing variation method
Description	K2-146 is a cool, 0.358M dwarf that was found to host a mini-Neptune with a 2.67 day period. The planet exhibited strong transit timing variations (TTVs) of greater than 30 minutes, indicative of the presence of an additional object in the system. Here we report the discovery of the previously undetected outer planet in the system, K2-146 c, using additional photometric data. K2-146 c was found to have a grazing transit geometry and a 3.97 day period. The outer planet was only significantly detected in the latter K2 campaigns presumably because of precession of its orbital plane. The TTVs of K2-146 b and c were measured using observations spanning a baseline of almost 1200 days. We found strong anti -correlation in the TTVs, suggesting the two planets are gravitationally interacting. Our TTV and transit model analyses revealed that K2-146 b has a radius of 2.25 0.10 Re and a mass of 5.6 0.7 Me, whereas K2-146 c has a radius of 2.591 Re and a mass of 7.1 0.9 Me. The inner and outer planets likely have moderate eccentricities of e = 0.14 0.07 and 0.16 0.07, respectively. Long-term numerical integrations of the two -planet orbital solution show that it can be dynamically stable for at least 2 Myr. We show that the resonance angles of the planet pair are librating, which may be an indication that K2-146 b and c are in a 3:2 mean motion resonance. The orbital architecture of the system points to a possible convergent migration origin.