Browsing by Author "Kunimoto, Michelle"

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    A 2:1 Mean-motion Resonance Super-Jovian Pair Revealed by TESS, FEROS, and HARPS
    (2023) Bozhilov, Vladimir; Antonova, Desislava; Hobson, Melissa J.; Brahm, Rafael; Jordan, Andres; Henning, Thomas; Eberhardt, Jan; Rojas, Felipe I.; Batygin, Konstantin; Torres-Miranda, Pascal; Stassun, Keivan G.; Millholland, Sarah C.; Stoeva, Denitza; Minev, Milen; Espinoza, Nestor; Ricker, George R.; Latham, David W.; Dragomir, Diana; Kunimoto, Michelle; Jenkins, Jon M.; Ting, Eric B.; Seager, Sara; Winn, Joshua N.; Villasenor, Jesus Noel; Bouma, Luke G.; Medina, Jennifer; Trifonov, Trifon
    We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for planet formation and orbital evolution analysis. The system was discovered thanks to a single-transit event recorded by the Transiting Exoplanet Survey Satellite mission, which pointed to a Jupiter-sized companion with poorly constrained orbital parameters. We began ground-based precise radial velocity (RV) monitoring with HARPS and FEROS within the Warm gIaNts with tEss survey to constrain the transiting body's period, mass, and eccentricity. The RV measurements revealed not one but two massive planets with periods of 76.80(-0.06)(+0.06) and 155.3(-0.7)(+0.7) days, respectively. A combined analysis of transit and RV data yields an inner transiting planet with a mass of 6.14(-0.42)(+0.39) M-Jup and a radius of 1.00(-0.04)(+0.04) R-Jup, and an outer planet with a minimum mass of 8.02(-0.18)(+0.18) M-Jup, indicating a massive giant pair. A detailed dynamical analysis of the system reveals that the planets are locked in a strong firstorder, eccentricity-type 2:1 MMR, which makes TIC 279401253 one of the rare examples of truly resonant architectures supporting disk-induced planet migration. The bright host star, V approximate to 11.9 mag, the relatively short orbital period (P-b = 76.80(-0.06)(+0.06) days), and pronounced eccentricity (e = 0.448(-0.029)(+0.029)) make the transiting planet a valuable target for atmospheric investigation with the James Webb Space Telescope and ground-based extremely large telescopes.
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    THE GEOMETRY OF THE INFRARED AND X-RAY OBSCURER IN A DUSTY HYPERLUMINOUS QUASAR
    (2016) Farrah, Duncan; Balokovic, Mislav; Stern, Daniel; Harris, Kathryn; Kunimoto, Michelle; Walton, Dominic J.; Alexander, David M.; Arévalo, Patricia; Bauer, Franz Erik; Claudio Ricci
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    TOpI-2447 b / NGTS-29 b: a 69-day Saturn around a Solar analogue
    (2024) Gill, Samuel; Bayliss, Daniel; Ulmer-Moll, Solene; Wheatley, Peter J.; Brahm, Rafael; Anderson, David R.; Armstrong, David; Apergis, Ioannis; Alves, Douglas R.; Burleigh, Matthew R.; Butler, R. P.; Bouchy, Francois; Battley, Matthew P.; Bryant, Edward M.; Bieryla, Allyson; Crane, Jeffrey D.; Collins, Karen A.; Casewell, Sarah L.; Carleo, Ilaria; Claringbold, Alastair B.; Dalba, Paul A.; Dragomir, Diana; Eigmueller, Philipp; Eberhardt, Jan; Fausnaugh, Michael; Gunther, Maximilian N.; Grieves, Nolan; Goad, Michael R.; Gillen, Edward; Hagelberg, Janis; Hobson, Melissa; Hedges, Christina; Henderson, Beth A.; Hawthorn, Faith; Henning, Thomas; Jones, Matias, I; Jordan, Andres; Jenkins, James S.; Kunimoto, Michelle; Krenn, Andreas F.; Kendall, Alicia; Lendl, Monika; McCormac, James; Moyano, Maximiliano; Torres-Miranda, Pascal; Nielsen, Louise D.; Osborn, Ares; Otegi, Jon; Osborn, Hugh; Quinn, Samuel N.; Rodriguez, Joseph E.; Ramsay, Gavin; Schlecker, Martin; Shectman, Stephen A.; Seager, Sara; Tilbrook, Rosanna H.; Trifonov, Trifon; Teske, Johanna K.; Udry, Stephane; Vines, Jose, I; West, Richard R.; Wohler, Bill; Winn, Joshua N.; Wang, Sharon X.; Zhou, George; Zivave, Tafadzwa
    Discovering transiting exoplanets with relatively long orbital periods (>10 d) is crucial to facilitate the study of cool exoplanet atmospheres (T-eq < 700 K) and to understand exoplanet formation and inward migration further out than typical transiting exoplanets. In order to discover these longer period transiting exoplanets, long-term photometric, and radial velocity campaigns are required. We report the discovery of TOI-2447 b (=NGTS-29 b), a Saturn-mass transiting exoplanet orbiting a bright (T = 10.0) Solar-type star (T-eff = 5730 K). TOI-2447 b was identified as a transiting exoplanet candidate from a single transit event of 1.3 per cent depth and 7.29 h duration in TESS Sector 31 and a prior transit event from 2017 in NGTS data. Four further transit events were observed with NGTS photometry which revealed an orbital period of P = 69.34 d. The transit events establish a radius for TOI-2447 b of 0.865 +/- 0.010 R-J, while radial velocity measurements give a mass of 0.386 +/- 0.025 M-J. The equilibrium temperature of the planet is 414 K, making it much cooler than the majority of TESS planet discoveries. We also detect a transit signal in NGTS data not caused by TOI-2447 b, along with transit timing variations and evidence for a similar to 150 d signal in radial velocity measurements. It is likely that the system hosts additional planets, but further photometry and radial velocity campaigns will be needed to determine their parameters with confidence. TOI-2447 b/NGTS-29 b joins a small but growing population of cool giants that will provide crucial insights into giant planet composition and formation mechanisms.