Examinando por Autor "Sousa, Sergio G."

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    HD 213885b: A transiting 1-d-period super-Earth with an Earth-like composition around a bright (V = 7.9) star unveiled by TESS
    (Oxford University Press, 2020-01-01) Espinoza, Néstor; Brahm, Rafael; Henning, Thomas; Jordán, Andrés; Dorn, Caroline; Rojas, Felipe; Sarkis, Paula; Kossakowski, Diana; Schlecker, Martin; Díaz, Matías R.; Jenkins, James S.; Aguilera-Gomez, Claudia; Jenkins, Jon M.; Twicken, Joseph D.; Collins, Karen A.; Lissauer, Jack; Armstrong, David J.; Adibekyan, Vardan; Barrado, David; Barros, Susana C.C.; Battley, Matthew; Bayliss, Daniel; Bouchy, François; Bryant, Edward M.; Cooke, Benjamin F.; Olivier D.S.; Dumusque, Xavier; Figueira, Pedro; Giles, Helen; Lillo-Box, Jorge; Lovis, Christophe; Nielsen, Louise D.; Pepe, Francesco; Pollacco, Don; Santos, Nuno C.; Sousa, Sergio G.; Udry, Stéphane; Wheatley, Peter J.; Turner, Oliver; Marmier, Maxime; Ségransan, Damien; Ricker, George; Latham, David; Seager, Sara; Winn, Joshua N.; Kielkopf, John F.; Hart, Rhodes; Wingham, Geof; Jensen, Eric L.N.; Hełminiak, Krzysztof G.; Tokovinin A.; Briceño C.; Ziegler, Carl; Law, Nicholas M.; Mann, Andrew W.; Daylan, Tansu; Doty, John P.; Guerrero, Natalia; Boyd, Patricia; Crossfield, Ian
    We report the discovery of the 1.008-d, ultrashort period (USP) super-Earth HD 213885b (TOI-141b) orbiting the bright (V= 7.9) star HD 213885 (TOI-141, TIC 403224672), detected using photometry from the recently launched TESS mission. Using FEROS, HARPS, and CORALIE radial velocities, we measure a precise mass of 8.8 ±0.6M⊙ for this 1.74±0.05R⊙ exoplanet, which provides enough information to constrain its bulk composition - similar to Earth's but enriched in iron. The radius, mass, and stellar irradiation of HD 213885b are, given our data, very similar to 55 Cancri e, making this exoplanet a good target to perform comparative exoplanetology of short period, highly irradiated super-Earths. Our precise radial velocities reveal an additional 4.78-d signal which we interpret as arising from a second, non-transiting planet in the system, HD 213885c, whose minimum mass of 19.9 ± 1.4 M⊙ makes it consistent with being a Neptune-mass exoplanet. The HD 213885 system is very interesting from the perspective of future atmospheric characterization, being the second brightest star to host an USP transiting super-Earth (with the brightest star being, in fact, 55 Cancri). Prospects for characterization with present and future observatories are discussed.
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    The metallicity–period–mass diagram of low-mass exoplanets
    (Monthly Notices of the Royal Astronomical Society, 2019-02-28) Sousa, Sergio G.; Adibekyan, Vardan; Santos, Nuno C.; Mortier, Annelies; Barros, Susana C. C.; Delgado-Mena, Elisa; Demangeon, Olivier; Israelian, Garik; Faria, Joao P.; Figueira, Pedro; Rojas-Ayala, Barbara; Tsantaki, Maria; Andreasen, Daniel T.; Brandao, Isa; Ferreira, Andressa C. S.; Montalto, Marco; Santerne, Alexandre
    The number of exoplanet detections continues to grow following the development of better instruments and missions. Key steps for the understanding of these worlds comes from their characterization and statistical studies. We explore the metallicity–period–mass diagram for known exoplanets by using an updated version of The Stellar parameters for stars with ExoplanETs CATalogue (SWEET-Cat), a unique compilation of precise stellar parameters for planet–host stars provided for the exoplanet community. Here, we focus on the planets with minimum mass below 30 M which seems to present a possible correlation in the metallicity–period–mass diagram where the mass of the planet increases with both metallicity and period. Our analysis suggests that the general observed correlation may not be fully explained by observational biases. Additional precise data will be fundamental to confirm or deny this possible correlation.