Mass determinations of the three mini-Neptunes transiting TOI-125

Creators: Nielsen, L. D.; Gandolfi, D.; Armstrong, D. J.; Jenkins, J. S.; Fridlund, M.; Santos, N. C.; Dai, F.; Adibekyan, V.; Luque, R.; Steffen, J. H.; Esposito, M.; Meru, F.; Sabotta, S.; Bolmont, E.; Kossakowski, D.; Otegi, J. F.; Murgas, F.; Stalport, M.; Rodler, F.; Díaz, M. R.; Kurtovic, N. T.; Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J. N.; Jenkins, J. M.; Allart, R.; M. Almenara, J.; Barrado, D.; Barros, S. C. C.; Bayliss, D.; Berdiñas, Z. M.; Boisse, I.; Bouchy, F.; Boyd, P.; Brown, D. J. A.; Bryant, E. M.; Burke, C.; Cochran, W. D.; Cooke, B. F.; Demangeon, O. D. S.; Díaz, R. F.; Dittman, J.; Dorn, C.; Dumusque, X.; García, R. A.; González-Cuesta, L.; Grziwa, S.; Georgieva, I.; Guerrero, N.; Hatzes, A. P.; Helled, R.; Henze, C. E.; Hojjatpanah, S.; Korth, J.; Lam, K. W. F.; Lillo-Box, J.; Lopez, T. A.; Livingston, J,; Mathur, S.; Mousis, O.; Narita, N.; Osborn, H. P.; Palle, E.; Peña Rojas, P. A.; Persson, C. M.; Quinn, S. N.; Rauer, H.; Redfield, S.; Santerne, A.; dos Santos, L. A.; Seidel, J. V.; Sousa, S..G.; Ting, E. B.; Turbet, M.; Udry, S.; Vanderburg, A.; Van Eylen, V.; Vines, J. I.; Wheatley, P. J.; Wilson, P. A.

Abstract

The Transiting Exoplanet Survey Satellite, TESS, is currently carrying out an all-sky search for small planets transiting bright stars. In the first year of the TESS survey, a steady progress was made in achieving the mission's primary science goal of establishing bulk densities for 50 planets smaller than Neptune. During that year, the TESS's observations were focused on the southern ecliptic hemisphere, resulting in the discovery of three mini-Neptunes orbiting the star TOI-125, a V = 11.0 K0 dwarf. We present intensive HARPS radial velocity observations, yielding precise mass measurements for TOI-125b, TOI-125c, and TOI-125d. TOI-125b has an orbital period of 4.65 d, a radius of 2.726 ± 0.075 R_E, a mass of 9.50 ± 0.88 M_E, and is near the 2:1 mean motion resonance with TOI-125c at 9.15 d. TOI-125c has a similar radius of 2.759 ± 0.10 R_E and a mass of 6.63 ± 0.99 M_E, being the puffiest of the three planets. TOI-125d has an orbital period of 19.98 d and a radius of 2.93 ± 0.17 R_E and mass 13.6 ± 1.2 M_E. For TOI-125b and d, we find unusual high eccentricities of 0.19 ± 0.04 and 0.17^(+0.08)_(−0.06), respectively. Our analysis also provides upper mass limits for the two low-SNR planet candidates in the system; for TOI-125.04 (R_P = 1.36 R_E, P = 0.53 d), we find a 2σ upper mass limit of 1.6 M_E, whereas TOI-125.05 (⁠RP=4.2^(+2.4)_(−1.4) R_E, P = 13.28 d) is unlikely a viable planet candidate with an upper mass limit of 2.7 M_E. We discuss the internal structure of the three confirmed planets, as well as dynamical stability and system architecture for this intriguing exoplanet system.

Additional Information

© 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Received: 03 December 2019; Revision received: 17 January 2020; Accepted: 17 January 2020; Published: 23 January 2020. We thank the anonymous referee for providing thoughtful comments that allowed us to improve on this paper. This study is based on observations collected at the European Southern Observatory under ESO programmes 0101.C-0829, 1102.C-0249, 1102.C-0923, 0102.C-0525, and 0102.C-0451. We thank the Swiss National Science Foundation (SNSF) and the Geneva University for their continuous support to our planet search programs. This work has been in particular carried out in the framework of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). This publication makes use of DACE, which is a facility based at the University of Geneva (CH) dedicated to extrasolar planets data visualization, exchange, and analysis. DACE is a platform of the Swiss National Centre of Competence in Research (NCCR) PlanetS, federating the Swiss expertise in exoplanet research. The DACE platform is available at https://dace.unige.ch. This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Explorer Program. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. DJA acknowledges support from the STFC via an Ernest Rutherford Fellowship (ST/R00384X/1). The IA/Portuguese team was supported by FCT/MCTES through national funds and by FEDER – Fundo Europeu de Desenvolvimento Regional through COMPETE2020 – Programa Operacional Competitividade e Internacionalização by these grants: UID/FIS/04434/2019; PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER-032113; PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953. VA acknowledges the support from FCT through Investigador FCT contract no. IF/00650/2015/CP1273/CT0001. SH acknowledges support by the fellowships PD/BD/128119/2016 funded by FCT (Portugal). SCCB acknowledges support from FCT through Investigador FCT contracts IF/01312/2014/CP1215/CT0004. ODSD acknowledges the support from FCT (Portugal) through work contract DL 57/2016/CP1364/CT0004. MRD acknowledges support of CONICYT-PFCHA/Doctorado Nacional-21140646 and Proyecto Basal AFB-170002. JSJ acknowledges support from FONDECYT grant 1161218. FM acknowledges support from The Royal Society Dorothy Hodgkin Fellowship. JVS and LAdS are supported by funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project FOUR ACES; grant agreement no. 724427). DJAB acknowledges support from the UK Space Agency. JNW acknowledges support from the Heising-Simons Foundation. NN is supported by JSPS KAKENHI Grant Numbers JP18H01265 and JP18H05439, and JST PRESTO Grant Number JPMJPR1775. CD acknowledges support from the Swiss National Science Foundation under grant PZ00P2_174028. KWFL acknowledges support by DFG grants RA714/14-1 within the DFG Schwerpunkt SPP 1992, 'Exploring the Diversity of Extrasolar Planets'. DB and JLB have been funded by the Spanish State Research Agency (AEI) Project No. ESP2017-87676-C5-1-R and No. MDM-2017-0737 Unidad de Excelencia María de Maeztu Centro de Astrobiología (CSIC-INTA). SM acknowledges support from the Spanish Ministry under the Ramon y Cajal fellowship number RYC-2015-17697. RAG acknowledges the support from PLATO and GOLF CNES grants. This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 832738/ESCAPE. MT acknowledges funding from the Gruber Foundation. MF, IG, and CMP gratefully acknowledge the support of the Swedish National Space Agency (DNR 163/16 and 174/18).

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