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TOI-2119: a transiting brown dwarf orbiting an active M-dwarf from NASA’s TESS mission

Carmichael, Theron W. and Irwin, Jonathan M. and Murgas, Felipe and Pallé, Enric and Stassun, Keivan G. and Bartnik, Matthew and Collins, Karen A. and de Leon, Jerome and Esparza-Borges, Emma and Fedewa, Jeremy and Fong, William and Fukui, Akihiko and Jenkins, Jon M. and Kagetani, Taiki and Latham, David W. and Lund, Michael B. and Mann, Andrew W. and Moldovan, Dan and Morgan, Edward H. and Narita, Norio and Painter, Shane and Parviainen, Hannu and Quintana, Elisa V. and Ricker, George R. and Schulte, Jack and Schwarz, Richard P. and Seager, Sara and Sokolovsky, Kirill and Twicken, Joseph D. and Winn, Joshua N. (2022) TOI-2119: a transiting brown dwarf orbiting an active M-dwarf from NASA’s TESS mission. Monthly Notices of the Royal Astronomical Society, 514 (4). pp. 4944-4957. ISSN 0035-8711. doi:10.1093/mnras/stac1666.

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We report the discovery of TOI-2119b, a transiting brown dwarf (BD) that orbits and is completely eclipsed by an active M-dwarf star. Using light-curve data from the Transiting Exoplanet Survey Satellite mission and follow-up high-resolution Doppler spectroscopic observations, we find the BD has a radius of R_b = 1.08 ± 0.03 R_J, a mass of M_b = 64.4 ± 2.3 M_J, an orbital period of P = 7.200865 ± 0.00002 d, and an eccentricity of e = 0.337 ± 0.002. The host star has a mass of M⋆ = 0.53 ± 0.02 M_⊙, a radius of R⋆ = 0.50 ± 0.01 R_⊙, an effective temperature of T_(eff) = 3621 ± 48K, and a metallicity of [Fe/H] = +0.06 ± 0.08⁠. TOI-2119b joins an emerging population of transiting BDs around M-dwarf host stars, with TOI-2119 being the ninth such system. These M-dwarf–brown dwarf systems typically occupy mass ratios near q = M_b/M⋆ ≈ 0.1−0.2, which separates them from the typical mass ratios for systems with transiting substellar objects and giant exoplanets that orbit more massive stars. The nature of the secondary eclipse of the BD by the star enables us to estimate the effective temperature of the substellar object to be 2030 ± 84K, which is consistent with predictions by substellar evolutionary models.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemMikulski Archive for Space Telescopes (MAST) ItemEXOFASTv2
Carmichael, Theron W.0000-0001-6416-1274
Murgas, Felipe0000-0001-9087-1245
Pallé, Enric0000-0003-0987-1593
Stassun, Keivan G.0000-0002-3481-9052
Collins, Karen A.0000-0001-6588-9574
de Leon, Jerome0000-0002-6424-3410
Esparza-Borges, Emma0000-0002-2341-3233
Fong, William0000-0003-0241-2757
Fukui, Akihiko0000-0002-4909-5763
Jenkins, Jon M.0000-0002-4715-9460
Kagetani, Taiki0000-0002-5331-6637
Latham, David W.0000-0001-9911-7388
Lund, Michael B.0000-0003-2527-1598
Mann, Andrew W.0000-0003-3654-1602
Morgan, Edward H.0000-0003-1447-6344
Narita, Norio0000-0001-8511-2981
Parviainen, Hannu0000-0001-5519-1391
Quintana, Elisa V.0000-0003-1309-2904
Ricker, George R.0000-0003-2058-6662
Schwarz, Richard P.0000-0001-8227-1020
Seager, Sara0000-0002-6892-6948
Sokolovsky, Kirill0000-0001-5991-6863
Twicken, Joseph D.0000-0002-6778-7552
Winn, Joshua N.0000-0002-4265-047X
Additional Information:© The Author(s) 2022. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Received: 17 February 2022. Revision received: 19 May 2022. Accepted: 07 June 2022. Published: 16 June 2022. Corrected and typeset: 06 July 2022. Funding for the TESS  mission is provided by NASA’s Science Mission directorate. This paper includes data collected by the TESS mission, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). 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. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. This work makes use of observations from the LCOGT network. Part of the LCOGT telescope time was granted by NOIRLab through the Mid-Scale Innovations Program (MSIP). MSIP is funded by NSF. This work is partly supported by JSPS KAKENHI Grant Number JP18H05439, JST CREST Grant Number JPMJCR1761, the Astrobiology Center of National Institutes of Natural Sciences (NINS) (Grant Number AB031010). This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. EE-B acknowledges financial support from the European Union and the State Agency of Investigation of the Spanish Ministry of Science and Innovation (MICINN) under the grant PRE2020-093107 of the Pre-Doc Program for the Training of Doctors (FPI-SO) through FSE funds. TWC acknowledges the efforts of the members of the TESS  Follow-up Program and the Science Processing Operations Center in making the TESS  data readily accessible for the analysis in this work. DATA AVAILABILITY. The light curve data underlying this article were accessed from the Mikulski Archive for Space Telescopes (MAST) at We strongly recommend the use of lightkurve or similar software package for the management of any TESS  data products. The derived light-curve data generated in this research will be shared on reasonable request to the corresponding author. All data used in the analysis of the stellar and brown dwarf parameters are queried and properly formatted by EXOFASTv2 from their respective databases (see Section 3.1). The installation and use instructions for EXOFASTv2 can be found at
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)JP18H05439
Japan Science and Technology AgencyJPMJCR1761
National Institutes of Natural Sciences of JapanAB031010
Gaia Multilateral AgreementUNSPECIFIED
Ministerio de Ciencia e Innovación (MICINN)PRE2020-093107
Subject Keywords:techniques: photometric, techniques: radial velocities, techniques: spectroscopic, (stars:) brown dwarfs, stars: low-mass
Issue or Number:4
Record Number:CaltechAUTHORS:20220802-742059000
Persistent URL:
Official Citation:Theron W Carmichael, Jonathan M Irwin, Felipe Murgas, Enric Pallé, Keivan G Stassun, Matthew Bartnik, Karen A Collins, Jerome de Leon, Emma Esparza-Borges, Jeremy Fedewa, William Fong, Akihiko Fukui, Jon M Jenkins, Taiki Kagetani, David W Latham, Michael B Lund, Andrew W Mann, Dan Moldovan, Edward H Morgan, Norio Narita, Shane Painter, Hannu Parviainen, Elisa V Quintana, George R Ricker, Jack Schulte, Richard P Schwarz, Sara Seager, Kirill Sokolovsky, Joseph D Twicken, Joshua N Winn, TOI-2119: a transiting brown dwarf orbiting an active M-dwarf from NASA’s TESS mission, Monthly Notices of the Royal Astronomical Society, Volume 514, Issue 4, August 2022, Pages 4944–4957,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116008
Deposited By: George Porter
Deposited On:03 Aug 2022 14:39
Last Modified:03 Aug 2022 14:39

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