Examinando por Autor "Rojas, Felipe"

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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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    Stochastic simulation model of attention to response to electrical distribution system faults
    (Elsevier B.V., 2023-03) Jara, Mario; Sabattin, Jorge; Rojas, Felipe; Reyes, Hector; Jones, Francisco; Portales, Hector; Reyes, Marcelo; Gatica, Gustavo; Aliaga, Erwin; Calderon-Ochoa, Andres; Coronado-Hernandez, Jairo R.
    Queuing theory allows simulating scenarios applied to requirements of events of stochastic origin to solve problems in the attention service of electrical networks. Regarding emergency reactions, companies may experience response time delays due to incorrect sizing of the number of crew members, among other parameters. So is the case for a company in the Chilean energy sector called Enel, which is currently experiencing response delay issues. A complete formulation is presented, which can be easily used for planning the crews required for attention to the response to electrical distribution system faults. The formulation is applied to an electrical distribution company located in Chile. © 2023 Elsevier B.V.. All rights reserved.