TESS Spots a Super-puff: The Remarkably Low Density of TOI-1420b

Yoshida, Stephanie and Vissapragada, Shreyas and Latham, David W. and Bieryla, Allyson and Thorngren, Daniel P. and Eastman, Jason D. and López-Morales, Mercedes and Barkaoui, Khalid and Beichman, Charles and Berlind, Perry and Buchave, Lars A. and Calkins, Michael L. and Ciardi, David R. and Collins, Karen A. and Cosentino, Rosario and Crossfield, Ian J. M. and Dai, Fei and DiTomasso, Victoria and Dowling, Nicholas and Esquerdo, Gilbert A. and Forés-Toribio, Raquel and Ghedina, Adriano and Goliguzova, Maria V. and Golub, Eli and Gonzales, Erica J. and Horta, Ferran Grau and Higuera, Jesus and Hoch, Nora and Horne, Keith and Howell, Steve B. and Jenkins, Jon M. and Klusmeyer, Jessica and Laloum, Didier and Lissauer, Jack J. and Logsdon, Sarah E. and Malavolta, Luca and Matson, Rachel A. and Matthews, Elisabeth C. and McLeod, Kim K. and Medina, Jennifer V. and Muñoz, Jose A. and Osborn, Hugh P. and Safonov, Boris and Schlieder, Joshua and Schmidt, Michael and Schweiker, Heidi and Seager, Sara and Sozzetti, Alessandro and Srdoc, Gregor and Stefánsson, Guđmundur and Strakhov, Ivan A. and Striegel, Stephanie and Villaseñor, Joel and Winn, Joshua N. (2023) TESS Spots a Super-puff: The Remarkably Low Density of TOI-1420b. The Astronomical Journal, 166 (5). p. 181. ISSN 0004-6256

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Abstract

We present the discovery of TOI-1420b, an exceptionally low-density (ρ = 0.08 ± 0.02 g cm−3) transiting planet in a P = 6.96 days orbit around a late G-dwarf star. Using transit observations from TESS, LCOGT, Observatoire Privé du Mont, Whitin, Wendelstein, OAUV, Ca l'Ou, and KeplerCam, along with radial velocity observations from HARPS-N and NEID, we find that the planet has a radius of Rp = 11.9 ± 0.3R⊕ and a mass of Mp = 25.1 ± 3.8M⊕. TOI-1420b is the largest known planet with a mass less than 50M⊕, indicating that it contains a sizeable envelope of hydrogen and helium. We determine TOI-1420b's envelope mass fraction to be ${f}_{\mathrm{env}}={82}_{-6}^{+7} \% $, suggesting that runaway gas accretion occurred when its core was at most four to five times the mass of the Earth. TOI-1420b is similar to the planet WASP-107b in mass, radius, density, and orbital period, so a comparison of these two systems may help reveal the origins of close-in low-density planets. With an atmospheric scale height of 1950 km, a transmission spectroscopy metric of 580, and a predicted Rossiter–McLaughlin amplitude of about 17 m s−1, TOI-1420b is an excellent target for future atmospheric and dynamical characterization.

Item Type: Article
Subjects: Universal Eprints > Physics and Astronomy
Depositing User: Managing Editor
Date Deposited: 11 Nov 2023 03:52
Last Modified: 11 Nov 2023 03:52
URI: http://journal.article2publish.com/id/eprint/3121

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