Spinning up a Daze: TESS Uncovers a Hot Jupiter Orbiting the Rapid Rotator TOI-778
Bieryla, Allyson; Latham, David W.; Quinn, Samuel N.; Berlind, Perry; Esquerdo, Gilbert A.; Jordán, Andrés; Brahm, Rafael; Kane, Stephen R.; Zhou, George; Bayliss, Daniel; Tan, Thiam-Guan; Wittenmyer, Robert A.; Howell, Steve B.; Horner, Jonathan; Fetherolf, Tara; Jones, Matías I.; Collins, Karen A.; Ricker, George R.; Vanderspek, Roland; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Günther, Maximilian N.; Shporer, Avi; Ciardi, David R.; Lund, Michael B.; McCormac, James; Udry, Stéphane; Rodriguez, Joseph E.; Stockdale, Chris; Jensen, Eric L. N.; Kielkopf, John F.; Bowler, Brendan P.; Smith, Alexis M. S.; Bryant, Edward M.; Wang, Songhu; Bouchy, François; Nielsen, Louise D.; Brown, Carolyn J.; Dressing, Courtney D.; Plavchan, Peter; Hinkel, Natalie R.; Schwarz, Richard P.; Christiansen, Jessie L.; Tinney, C. G.; Clark, Jake T.; Okumura, Jack; Wright, Duncan J.; Díaz, Matías R.; Wingham, Geof; Heitzmann, Alexis; Addison, Brett C.; Mengel, Matthew W.; Davis, Allen B.; Radford, Don J.; Ballard, Sarah; Vach, Sydney; Errico, Adriana; Clerté, Mathieu; Hui-Gen, Liu; Lee, Annette S.; David, Avelyn; Heim, Jessica; Lee, Michele E.; Sevilla, Verónica; Zafar, Naqsh E.; Allen, Bridgette E.; Berberyan, Arthur; Ciardi, Krys N.; Dallant, Jules; Harre, Jan-Vincent; Otegi, Jon
Australia, United States, United Kingdom, China, Switzerland, Chile, Germany, Netherlands, New Zealand
Abstract
NASA's Transiting Exoplanet Survey Satellite (TESS) mission has been uncovering a growing number of exoplanets orbiting nearby, bright stars. Most exoplanets that have been discovered by TESS orbit narrow-line, slow-rotating stars, facilitating the confirmation and mass determination of these worlds. We present the discovery of a hot Jupiter orbiting a rapidly rotating ( $v\sin \,(i)=35.1\pm 1.0$ km s-1) early F3V-dwarf, HD 115447 (TOI-778). The transit signal taken from Sectors 10 and 37 of TESS's initial detection of the exoplanet is combined with follow-up ground-based photometry and velocity measurements taken from MINERVA-Australis, TRES, CORALIE, and CHIRON to confirm and characterize TOI-778 b. A joint analysis of the light curves and the radial velocity measurements yields a mass, a radius, and an orbital period for TOI-778 b of ${2.76}_{-0.23}^{+0.24}$ M J, 1.370 ± 0.043 R J, and ~4.63 days, respectively. The planet orbits a bright (V = 9.1 mag) F3-dwarf with M = 1.40 ± 0.05 M ⊙, R = 1.70 ± 0.05 R ⊙, and $\mathrm{log}g=4.05\pm 0.17$ . We observed a spectroscopic transit of TOI-778 b, which allowed us to derive a sky-projected spin-orbit angle of 18° ± 11°, consistent with an aligned planetary system. This discovery demonstrates the capability of smaller-aperture telescopes such as MINERVA-Australis to detect the radial velocity signals produced by planets orbiting broad-line, rapidly rotating stars.