HIP 33609 b: An Eccentric Brown Dwarf Transiting a V = 7.3 Rapidly Rotating B Star
Kostov, Veselin B.; Torres, Guillermo; Vanderburg, Andrew; Lester, Kathryn V.; Triaud, Amaury H. M. J.; Bieryla, Allyson; Latham, David W.; Quinn, Samuel N.; Littlefield, Colin; Stassun, Keivan G.; Zhou, George; Howell, Steve B.; Ziegler, Carl; Collins, Karen A.; Ricker, George R.; Winn, Joshua N.; Jenkins, Jon M.; Seager, S.; Kraus, Adam L.; Howard, Saburo; Guillot, Tristan; Bendjoya, Philippe; Gasparetto, Thomas; Günther, Maximilian N.; Marie-Sainte, Wenceslas; Mékarnia, Djamel; Suarez, Olga; Shporer, Avi; Collins, Kevin I.; Rapetti, David; Mann, Andrew W.; Rodriguez, Joseph E.; Eastman, Jason D.; Levine, Alan M.; Sefako, Ramotholo; Vanderspek, R.; Osborn, Hugh P.; Srdoc, Gregor; Carmichael, Theron W.; Vowell, Noah; Hooton, Matthew J.; Buttu, Marco; ABE, Lyu; Bush, Jonathan L.; Fields, Matthew J.
United States, Australia, United Kingdom, France, Italy, Netherlands, Antarctica, Switzerland, South Africa, Croatia
Abstract
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 ( $v\sin {i}_{* }=55.6\pm 1.8$ 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.