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

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 RE, a mass of 9.50 ± 0.88 ME, 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 RE and a mass of 6.63 ± 0.99 ME, 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 RE and mass 13.6 ± 1.2 ME. 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 (RP = 1.36 RE, P = 0.53 d), we find a 2ó upper mass limit of 1.6 ME, whereas TOI-125.05 (RP = 4.2+2.4-1.4 RE, P = 13.28 d) is unlikely a viable planet candidate with an upper mass limit of 2.7 ME. We discuss the internal structure of the three confirmed planets, as well as dynamical stability and system architecture for this intriguing exoplanet system.

Original languageEnglish
Pages (from-to)5399-5412
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - 2020
Externally publishedYes


FundersFunder number
Doctorado Nacional-21140646AFB-170002
Gaia Data Processing and Analysis Consortium
Geneva University
Programa Operacional Competitividade e Internacionalização
Spanish Ministry under the Ramon y Cajal fellowshipRYC-2015-17697
Swiss National Centre of Competence inResearch
National Aeronautics and Space Administration
Ames Research Center
California Institute of Technology
Horizon 2020 Framework Programme851555
Gruber Foundation
UK Space Agency
Heising-Simons Foundation
Diabetes Patient Advocacy Coalition
Science and Technology Facilities CouncilST/R00384X/1
Royal Society
European Research Council
European Space Agency
Deutsche ForschungsgemeinschaftRA714/14-1
Japan Society for the Promotion of Science18H01265, JP18H05439
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
Swedish National Space Agency174/18, DNR 163/16
Fundação para a Ciência e a Tecnologia
Fondo Nacional de Desarrollo Científico y Tecnológico1161218
Ministério da Ciência, Tecnologia e Ensino SuperiorPTDC/FIS-AST/32113/2017, IF/01312/2014/CP1215/CT0004, PTDC/FIS-AST/28953/2017, PD/BD/128119/2016, DL 57/2016/CP1364/CT0004, POCI-01-0145-FEDER-028953, UID/FIS/04434/2019, IF/00650/2015/CP1273/CT0001, POCI-01-0145-FEDER-032113
Université de Genève
Horizon 2020832738, 724427
European Regional Development Fund
Precursory Research for Embryonic Science and TechnologyPZ00P2 174028, JPMJPR1775
Agencia Estatal de InvestigaciónMDM-2017-0737, ESP2017-87676-C5-1-R


    • Planets and satellites: detection
    • Planets and satellites: individual: (TOI-125, TIC 52368076)


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