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TESS-Keck Survey. V. twin Sub-Neptunes transiting the nearby G Star HD 63935
Scarsdale, Nicholas
Murphy, Joseph
Batalha, Natalie
Crossfield, Ian
Dressing, Courtney
Fulton, Benjamin
Howard, Andrew
Huber, Daniel
Isaacson, Howard
Kane, Stephen
Petigura, Erik
Robertson, Paul
Roy, Arpita
Weiss, Lauren
Beard, Corey
Behmard, Aida
Chontos, Ashley
Christiansen, Jessie
Ciardi, David
Claytor, Zachary
Collins, Karen
Collins, Kevin
Dai, Fei
Dalba, Paul
Dragomir, Diana
Fetherolf, Tara
Fukui, Akihiko
Giacalone, Steven
Gonzales, Erica
Hill, Michelle
Hirsch, Lea
Jensen, Eric
Kosiarek, Molly
de Leon, Jerome
Lubin, Jack
Lund, Michael
Luque, Rafael
Mayo, Andrew
Močnik, Teo
Mori, Mayuko
Narita, Norio
Nowak, Grzegorz
Pallé, Enric
Rosenthal, Lee
Rubenzahl, Ryan
Schlieder, Joshua
Shporer, Avi
Stassun, Keivan
Twicken, Joe
Wang, Gavin
Yahalomi, Daniel
Jenkins, Jon
Latham, David
Ricker, George
Seager, S.
Vanderspek, Roland
Winn, Joshua
IOP Publishing
2021
We present the discovery of two nearly identically sized sub-Neptune transiting planets orbiting HD 63935, a bright (V = 8.6 mag), Sun-like (Teff = 5560 K) star at 49 pc. TESS identified the first planet, HD 63935 b (TOI509.01), in Sectors 7 and 34. We identified the second signal (HD 63935 c) in Keck High Resolution Echelle Spectrometer and Lick Automated Planet Finder radial velocity data as part of our follow-up campaign. It was subsequently confirmed with TESS photometry in Sector 34 as TOI-509.02. Our analysis of the photometric and radial velocity data yielded a robust detection of both planets with periods of 9.0600 ± 0.007 and 21.40 ± 0.0019 days, radii of 2.99 ± 0.14 and 2.90 ± 0.13 R⊕, and masses of 10.8 ± 1.8 and 11.1 ± 2.4 M⊕. We calculated densities for planets b and c consistent with a few percent of the planet mass in hydrogen/helium envelopes. We also describe our survey’s efforts to choose the best targets for James Webb Space Telescope atmospheric followup. These efforts suggest that HD 63935 b has the most clearly visible atmosphere of its class. It is the best target for transmission spectroscopy (ranked by the transmission spectroscopy metric, a proxy for atmospheric observability) in the so far uncharacterized parameter space comprising sub-Neptune-sized (2.6 R⊕ < Rp < 4 R⊕), moderately irradiated (100 F⊕ < Fp < 1000 F⊕) planets around G stars. Planet c is also a viable target for transmission spectroscopy, and given the indistinguishable masses and radii of the two planets, the system serves as a natural laboratory for examining the processes that shape the evolution of sub-Neptune planets.
Mini Neptunes (1063)
Radial velocity (1332)
Transit photometry (1709)
Exoplanet atmospheres (487)