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http://hdl.handle.net/20.500.12386/31642
Title: | The Multiplanet System TOI-421: A Warm Neptune and a Super Puffy Mini-Neptune Transiting a G9 V Star in a Visual Binary* | Authors: | CARLEO, Ilaria Gandolfi, Davide Barragán, Oscar Livingston, John H. Persson, Carina M. Lam, Kristine W. F. Vidotto, Aline Lund, Michael B. Villarreal D'Angelo, Carolina Collins, Karen A. Fossati, Luca Schlieder, Joshua E. Ségransan, Damien Shectman, Stephen Skarka, Marek Smith, Alexis M. S. Smith, Jeffrey C. Stassun, Keivan Teske, Johanna Twicken, Joseph D. Van Eylen, Vincent Howard, Andrew W. Wang, Sharon Weiss, Lauren M. Wyttenbach, Aurélien Kubyshkina, Daria Brahm, Rafael Oklopčić, Antonija Mollière, Paul Redfield, Seth Serrano, Luisa Maria Dai, Fei Fridlund, Malcolm BORSA, Francesco Korth, Judith Esposito, Massimiliano Díaz, Matías R. Dyregaard Nielsen, Louise Hellier, Coel Mathur, Savita Deeg, Hans J. Hatzes, Artie P. BENATTI, SERENA Rodler, Florian Alarcon, Javier SPINA, LORENZO Santos, Ângela R. G. Georgieva, Iskra García, Rafael A. González-Cuesta, Lucía Ricker, George R. Vanderspek, Roland Latham, David W. Seager, Sara Winn, Joshua N. Jenkins, Jon M. Albrecht, Simon Batalha, Natalie M. Beard, Corey Boyd, Patricia T. Bouchy, François Burt, Jennifer A. Butler, R. Paul Cabrera, Juan Chontos, Ashley Ciardi, David R. Cochran, William D. Collins, Kevin I. Crane, Jeffrey D. Crossfield, Ian Csizmadia, Szilard Dragomir, Diana Dressing, Courtney Eigmüller, Philipp Endl, Michael Erikson, Anders Espinoza, Nestor Fausnaugh, Michael Feng, Fabo Flowers, Erin Fulton, Benjamin Gonzales, Erica J. Grieves, Nolan Grziwa, Sascha Guenther, Eike W. Guerrero, Natalia M. Henning, Thomas Hidalgo, Diego Hirano, Teruyuki Hjorth, Maria Huber, Daniel Isaacson, Howard Jones, Matias Jordán, Andrés Kabáth, Petr Kane, Stephen R. Knudstrup, Emil Lubin, Jack Luque, Rafael Mireles, Ismael Narita, Norio Nespral, David Niraula, Prajwal Nowak, Grzegorz Palle, Enric Pätzold, Martin Petigura, Erik A. Prieto-Arranz, Jorge Rauer, Heike Robertson, Paul Rose, Mark E. Roy, Arpita Sarkis, Paula |
Issue Date: | 2020 | Journal: | THE ASTRONOMICAL JOURNAL | Number: | 160 | Issue: | 3 | First Page: | 114 | Abstract: | We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations—comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Échelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements—and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P<SUB>b</SUB> = 5.19672 ± 0.00049 days, a mass of M<SUB>b</SUB> = 7.17 ± 0.66 M<SUB>⊕</SUB>, and a radius of R<SUB>b</SUB> = ${2.68}_{-0.18}^{+0.19}$ R<SUB>⊕</SUB>, whereas the outer warm Neptune, TOI-421 c, has a period of P<SUB>c</SUB> = 16.06819 ± 0.00035 days, a mass of M<SUB>c</SUB> = ${16.42}_{-1.04}^{+1.06}$ M<SUB>⊕</SUB>, a radius of R<SUB>c</SUB> = ${5.09}_{-0.15}^{+0.16}$ R<SUB>⊕</SUB>, and a density of ρ<SUB>c</SUB> = ${0.685}_{-0.072}^{+0.080}$ g cm<SUP>-3</SUP>. With its characteristics, the outer planet (ρ<SUB>c</SUB> = ${0.685}_{-0.072}^{+0.080}$ g cm<SUP>-3</SUP>) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Lyα transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH<SUB>4</SUB> in the atmosphere of TOI-421 c if equilibrium chemistry is assumed. <SUP>*</SUP> Based on observations made with ESO Telescopes at the La Silla Observatory under programs ID 1102.C-0923, 0103.C-0874, 0103.C-0759, 0103.C-0442, and 60.A-970. Based on observations obtained with the Nordic Optical Telescope (NOT), operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos (ORM) of the Instituto de Astrofísica de Canarias (IAC). This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. This work makes use of observations from the LCOGT network. | URI: | http://hdl.handle.net/20.500.12386/31642 | URL: | https://iopscience.iop.org/article/10.3847/1538-3881/aba124 https://api.elsevier.com/content/abstract/scopus_id/85093505241 |
ISSN: | 0004-6256 | DOI: | 10.3847/1538-3881/aba124 | Bibcode ADS: | 2020AJ....160..114C | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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2004.10095.pdf | preprint | 4.7 MB | Adobe PDF | View/Open |
Carleo_2020_AJ_160_114.pdf | [Administrators only] | 10.14 MB | Adobe PDF |
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