Examinando por Autor "Brahm, R."

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    Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602
    (American Astronomical Society (Aas), 2020) Bouma, L. G.; Hartman, J. D.; Brahm, R.; Evans, P.; Collins, K. A.; Zhou, G.; Sarkis, P.; Quinn, S. N.; De Leon, J.; Livingston, J.; Bergmann, C.; Stassun, K. G.; Bhatti, W.; Winn, J. N.; Bakos, G. Á.; Abe, L.; Crouzet, N.; Dransfield, G.; Guillot, T.; Marie-Sainte, W.; Mékarnia, D.; Triaud, A. H. M. J.; Tinney, C. G.; Henning, T.; Espinoza, N.; Jordán, A.; Barbieri, M.; Nandakumar, S.; Trifonov, T.; Vines, J. I.; Vuckovic, M.; Ziegler, C.; Law, N.; Mann, A. W.; Ricker, G. R.; Vanderspek, R.; Seager, S.; Jenkins, J. M.; Burke, C. J.; Dragomir, D.; Levine, A. M.; Quintana, E. V.; Rodriguez, J. E.; Smith, J. C.; Wohler, B.
    We report the discovery of TOI 837b and its validation as a transiting planet. We characterize the system using data from the NASA Transiting Exoplanet Survey Satellite mission, the ESA Gaia mission, ground-based photometry from El Sauce and ASTEP400, and spectroscopy from CHIRON, FEROS, and Veloce. We find that TOI 837 is a T = 9.9 mag G0/F9 dwarf in the southern open cluster IC 2602. The star and planet are therefore ${35}_{-5}^{+11}$ million years old. Combining the transit photometry with a prior on the stellar parameters derived from the cluster color–magnitude diagram, we find that the planet has an orbital period of $8.3\,\mathrm{days}$ and is slightly smaller than Jupiter (${R}_{{\rm{p}}}={0.77}_{-0.07}^{+0.09}\,{R}_{\mathrm{Jup}}$). From radial velocity monitoring, we limit ${M}_{{\rm{p}}}\sin i$ to less than 1.20 MJup (3σ). The transits either graze or nearly graze the stellar limb. Grazing transits are a cause for concern, as they are often indicative of astrophysical false-positive scenarios. Our follow-up data show that such scenarios are unlikely. Our combined multicolor photometry, high-resolution imaging, and radial velocities rule out hierarchical eclipsing binary scenarios. Background eclipsing binary scenarios, though limited by speckle imaging, remain a 0.2% possibility. TOI 837b is therefore a validated adolescent exoplanet. The planetary nature of the system can be confirmed or refuted through observations of the stellar obliquity and the planetary mass. Such observations may also improve our understanding of how the physical and orbital properties of exoplanets change in time.
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    Ítem
    Four Jovian planets around low-luminosity giant stars observed by the EXPRESS and PPPS
    (European Southern Observatory (ESO), 2021) Jones, M. I.; Wittenmyer, R.; Aguilera-Gómez, C.; Soto, M. G.; Torres, P.; Trifonov, T.; Jenkins, J. S.; Zapata, A.; Sarkis, P.; Zakhozhay, O.; Brahm, R.; Ramírez, R.; Santana, F.; Vines, J. I.; Díaz, M. R.; Vučković, M.; Pantoja, B.
    We report the discovery of planetary companions orbiting four low-luminosity giant stars with M⋆ between 1.04 and 1.39 M⊙. All four host stars have been independently observed by the EXoPlanets aRound Evolved StarS (EXPRESS) program and the Pan-Pacific Planet Search (PPPS). The companion signals were revealed by multi-epoch precision radial velocities obtained in nearly a decade. The planetary companions exhibit orbital periods between ~1.2 and 7.1 yr, minimum masses of mpsin i ~ 1.8–3.7 MJ, and eccentricities between 0.08 and 0.42. With these four new systems, we have detected planetary companions to 11 out of the 37 giant stars that are common targets in the EXPRESS and PPPS. After excluding four compact binaries from the common sample, we obtained a fraction of giant planets (mp ≳ 1– 2 MJ) orbiting within 5 AU from their parent star of f = 33.3−7.1+9.0%. This fraction is slightly higher than but consistent at the 1σ level with previous results obtained by different radial velocity surveys. Finally, this value is substantially higher than the fraction predicted by planet formation models of gas giants around stars more massive than the Sun.