Browsing by Author "Gandolfi, Davide"

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    K2-280 b - a low density warm sub-Saturn around a mildly evolved star
    (2020) Nowak, Grzegorz; Palle, Enric; Gandolfi, Davide; Deeg, Hans J.; Hirano, Teruyuki; Barragan, Oscar; Kuzuhara, Masayuki; Dai, Fei; Luque, Rafael; Persson, Carina M.; Fridlund, Malcolm; Johnson, Marshall C.; Korth, Judith; Livingston, John H.; Grziwa, Sascha; Mathur, Savita; Hatzes, Artie P.; Prieto-Arranz, Jorge; Nespral, David; Hidalgo, Diego; Hjorth, Maria; Albrecht, Simon; Van Eylen, Vincent; Lam, Kristine W. F.; Cochran, William D.; Esposito, Massimiliano; Csizmadia, Szilard; Guenther, Eike W.; Kabath, Petr; Blay, Pere; Brahm, Rafael; Jordan, Andres; Espinoza, Nestor; Rojas, Felipe; Casasayas Barris, Nuria; Rodler, Florian; Alonso Sobrino, Roi; Cabrera, Juan; Carleo, Ilaria; Chaushev, Alexander; de Leon, Jerome; Eigmueller, Philipp; Endl, Michael; Erikson, Anders; Fukui, Akihiko; Georgieva, Iskra; Gonzalez-Cuesta, Lucia; Knudstrup, Emil; Lund, Mikkel N.; Montanes Rodriguez, Pilar; Murgas, Felipe; Narita, Norio; Niraula, Prajwal; Paetzold, Martin; Rauer, Heike; Redfield, Seth; Ribas, Ignasi; Skarka, Marek; Smith, Alexis M. S.; Subjak, Jano
    We present an independent discovery and detailed characterization of K2-280 b, a transiting low density warm sub-Saturn in a 19.9-d moderately eccentric orbit (e = 0.35(-0.04)(+0.05)) from K2 campaign 7. A joint analysis of high precision HARPS, HARPS-N, and FIES radial velocity measurements and K2 photometric data indicates that K2-280 b has a radius of R-b = 7.50 +/- 0.44 R-circle plus and a mass of M-b = 37.1 +/- 5.6 M-circle plus, yielding a mean density of rho(b) = 0.48(-0.10)(+0.13) g cm(-3). The host star is a mildly evolved G7 star with an effective temperature of T-eff = 5500 +/- 100 K, a surface gravity of log g(star) = 4.21 +/- 0.05 (cgs), and an iron abundance of [Fe/H] = 0.33 +/- 0.08 dex, and with an inferred mass of M-star = 1.03 +/- 0.03 M-circle dot and a radius of R-star = 1.28 +/- 0.07 R-circle dot. We discuss the importance of K2-280 b for testing formation scenarios of sub-Saturn planets and the current sample of this intriguing group of planets that are absent in the Solar system.
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    Mass determination of two Jupiter-sized planets orbiting slightly evolved stars: TOI-2420 b and TOI-2485 b
    (2024) Carleo, Ilaria; Barragan, Oscar; Persson, Carina M.; Fridlund, Malcolm; Lam, Kristine W. F.; Messina, Sergio; Gandolfi, Davide; Smith, Alexis M. S.; Johnson, Marshall C.; Cochran, William; Osborne, Hannah L. M.; Brahm, Rafael; Ciardi, David R.; Collins, Karen A.; Everett, Mark E.; Giacalone, Steven; Guenther, Eike W.; Hatzes, Artie; Hellier, Coel; Horner, Jonathan; Kabath, Petr; Korth, Judith; MacQueen, Phillip; Masseron, Thomas; Murgas, Felipe; Nowak, Grzegorz; Rodriguez, Joseph E.; Watkins, Cristilyn N.; Wittenmyer, Rob; Zhou, George; Ziegler, Carl; Bieryla, Allyson; Boyd, Patricia T.; Clark, Catherine A.; Dressing, Courtney D.; Eastman, Jason D.; Eberhardt, Jan; Endl, Michael; Espinoza, Nestor; Fausnaugh, Michael; Guerrero, Natalia M.; Henning, Thomas; Hesse, Katharine; Hobson, Melissa J.; Howell, Steve B.; Jordan, Andres; Latham, David W.; Lund, Michael B.; Mireles, Ismael; Narita, Norio; Tala Pinto, Marcelo; Pugh, Teznie; Quinn, Samuel N.; Ricker, George; Rodriguez, David R.; Rojas, Felipe I.; Rose, Mark E.; Rudat, Alexander; Sarkis, Paula; Savel, Arjun B.; Schlecker, Martin; Schwarz, Richard P.; Seager, Sara; Shporer, Avi; Smith, Jeffrey C.; Stassun, Keivan G.; Stockdale, Chris; Trifonov, Trifon; Vanderspek, Roland; Winn, Joshua N.; Wright, Duncan
    Context. Hot and warm Jupiters might have undergone the same formation and evolution path, but the two populations exhibit different distributions of orbital parameters. This challenges our understanding of their actual origin. Aims. We report the results of our warm Jupiters survey, which was carried out with the CHIRON spectrograph within the KESPRINT collaboration. We addressed the question of the population origin by studying two planets that might help to bridge the gap between the two populations. Methods. We confirm two planets and determine their mass. One is a hot Jupiter (with an orbital period shorter than 10 days), TOI-2420 b, and the other is a warm Jupiter, TOI-2485 b. We analyzed them using a wide variety of spectral and photometric data in order to characterize these planetary systems. Results. We found that TOI-2420 b has an orbital period of P-b=5.8 days, a mass of M-b=0.9 M-J, and a radius of R-b=1.3 R-J, with a planetary density of 0.477 g cm(-3). TOI-2485 b has an orbital period of P-b=11.2 days, a mass of M-b=2.4 M-J, and a radius of R-b=1.1 R-J with a density of 2.36 g cm(-3). Conclusions. With the current parameters, the migration history for TOI-2420 b and TOI-2485 b is unclear: Scenarios of a high-eccentricity migration cannot be ruled out, and the characteristics of TOI-2485 b even support this scenario.
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    Stellar Astrophysics and Exoplanet Science with the Maunakea Spectroscopic Explorer (MSE)
    (2019) Bergemann, Maria; Huber, Daniel; Adibekyan, Vardan; Angelou, George; Barría, Daniela; Beers, Timothy C.; Beck, Paul G.; Bellinger, Earl P.; Bestenlehner, Joachim M.; Bitsch, Bertram; Burgasser, Adam; Buzasi, Derek; Cassisi, Santi; Catelan, Marcio; Escorza, Ana; Fleming, Scott W.; Gänsicke, Boris T.; Gandolfi, Davide; García, Rafael A.; Gieles, Mark; Karakas, Amanda; Lebreton, Yveline; Lodieu, Nicolas; Melis, Carl; Merle, Thibault; Mészáros, Szabolcs; Miglio, Andrea; Molaverdikhani, Karan; Monier, Richard; Morel, Thierry; Neilson, Hilding R.; Oshagh, Mahmoudreza; Rybizki, Jan; Serenelli, Aldo; Smiljanic, Rodolfo; Szabó, Gyula M.; Toonen, Silvia; Tremblay, Pier-Emmanuel; Valentini, Marica; Van Eck, Sophie; Zwintz, Konstanze; Bayo, Amelia; Cami, Jan; Casagrande, Luca; Gabdeev, Maksim; Gaulme, Patrick; Guiglion, Guillaume; Handler, Gerald; Hillenbrand, Lynne; Yildiz, Mutlu; Marley, Mark; Mosser, Benoit; Price-Whelan, Adrian M.; Prsa, Andrej; Hernández Santisteban, Juan V.; Silva Aguirre, Victor; Sobeck, Jennifer; Stello, Dennis; Szabo, Robert; Tsantaki, Maria; Villaver, Eva; Wright, Nicholas J.; Xu, Siyi; Zhang, Huawei; Anguiano, Borja; Bedell, Megan; Chaplin, Bill; Collet, Remo; Kamath, Devika; Martell, Sarah; Sousa, Sérgio G.; Ting, Yuan-Sen; Venn, Kim
    The Maunakea Spectroscopic Explorer (MSE) is a planned 11.25-m aperture facility with a 1.5 square degree field of view that will be fully dedicated to multi-object spectroscopy. A rebirth of the 3.6m Canada-France-Hawaii Telescope on Maunakea, MSE will use 4332 fibers operating at three different resolving powers (R ~ 2500, 6000, 40000) across a wavelength range of 0.36-1.8mum, with dynamical fiber positioning that allows fibers to match the exposure times of individual objects. MSE will enable spectroscopic surveys with unprecedented scale and sensitivity by collecting millions of spectra per year down to limiting magnitudes of g ~ 20-24 mag, with a nominal velocity precision of ~100 m/s in high-resolution mode. This white paper describes science cases for stellar astrophysics and exoplanet science using MSE, including the discovery and atmospheric characterization of exoplanets and substellar objects, stellar physics with star clusters, asteroseismology of solar-like oscillators and opacity-driven pulsators, studies of stellar rotation, activity, and multiplicity, as well as the chemical characterization of AGB and extremely metal-poor stars....