HIP 33609 b: An Eccentric Brown Dwarf Transiting a V = 7.3 Rapidly Rotating B Star

Noah Vowell, Joseph E. Rodriguez, Samuel N. Quinn, George Zhou, Andrew Vanderburg, Andrew W. Mann, Matthew J. Hooton, Keivan G. Stassun, Saburo Howard, Allyson Bieryla, David W. Latham, Steve B. Howell, Tristan Guillot, Carl Ziegler, Karen A. Collins, Theron W. Carmichael, Jon M. Jenkins, Avi Shporer, Lyu Abe, Philippe BendjoyaJonathan L. Bush, Marco Buttu, Kevin I. Collins, Jason D. Eastman, Matthew J. Fields, Thomas Gasparetto, Maximilian N. Günther, Veselin B. Kostov, Adam L. Kraus, Kathryn V. Lester, Alan M. Levine, Colin Littlefield, Wenceslas Marie-Sainte, Djamel Mékarnia, Hugh P. Osborn, David Rapetti, George R. Ricker, S. Seager, Ramotholo Sefako, Gregor Srdoc, Olga Suarez, Guillermo Torres, Amaury H.M.J. Triaud, R. Vanderspek, Joshua N. Winn

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite as TOI-588 b. HIP 33609 b is a large (R b = 1.580 − 0.070 + 0.074 R J) brown dwarf on a highly eccentric (e = 0.560 − 0.031 + 0.029 ) orbit with a 39 days period. The host star is a bright (V = 7.3 mag), T eff = 10,400 − 660 + 800 K star with a mass of M * = 2.383 − 0.095 + 0.10 M and radius of R * = 1.863 − 0.082 + 0.087 R , making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M b = 68.0 − 7.1 + 7.4 M J as well as the host star's rotation rate ( v sin i * = 55.6 ± 1.8 km s−1). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 ± 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.

Original languageEnglish (US)
Article number268
JournalAstronomical Journal
Issue number6
StatePublished - Jun 1 2023

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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