TOI-1235 b: A Keystone Super-Earth for Testing Radius Valley Emergence Models around Early M Dwarfs
Journal
Date Issued
2020
Author(s)
Cloutier, Ryan
•
Rodriguez, Joseph E.
•
Irwin, Jonathan
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Charbonneau, David
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Stassun, Keivan G.
•
Mortier, Annelies
•
Latham, David W.
•
Isaacson, Howard
•
Howard, Andrew W.
•
Udry, Stéphane
•
Wilson, Thomas G.
•
Watson, Christopher A.
•
•
Lienhard, Florian
•
•
Guerra, Pere
•
Collins, Karen A.
•
Beiryla, Allyson
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Esquerdo, Gilbert A.
•
Matthews, Elisabeth
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Matson, Rachel A.
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Howell, Steve B.
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Furlan, Elise
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Crossfield, Ian J. M.
•
Winters, Jennifer G.
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Nava, Chantanelle
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Ment, Kristo
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Lopez, Eric D.
•
Ricker, George
•
Vanderspek, Roland
•
Seager, Sara
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Jenkins, Jon M.
•
Ting, Eric B.
•
Tenenbaum, Peter
•
•
Sha, Lizhou
•
Ségransan, Damien
•
Schlieder, Joshua E.
•
Sasselov, Dimitar
•
Roy, Arpita
•
Robertson, Paul
•
Rice, Ken
•
•
Piotto, Giampaolo
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Phillips, David
•
Pepper, Joshua
•
Pepe, Francesco
•
•
Mocnik, Teo
•
•
Mayor, Michel
•
Martinez Fiorenzano, Aldo F.
•
Mallia, Franco
•
Lubin, Jack
•
Lovis, Christophe
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López-Morales, Mercedes
•
Kosiarek, Molly R.
•
Kielkopf, John F.
•
Kane, Stephen R.
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Jensen, Eric L. N.
•
•
Huber, Daniel
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Hill, Michelle L.
•
•
Gonzales, Erica
•
Giacalone, Steven
•
•
Ercolino, Andrea
•
Dumusque, Xavier
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Dressing, Courtney D.
•
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Dalba, Paul A.
•
•
Conti, Dennis M.
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Colón, Knicole D.
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Collins, Kevin I.
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Cameron, Andrew Collier
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Ciardi, David
•
Christiansen, Jessie
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Chontos, Ashley
•
•
Caldwell, Douglas A.
•
Burke, Christopher
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Buchhave, Lars
•
Beichman, Charles
•
Behmard, Aida
•
Beard, Corey
•
Akana Murphy, Joseph M.
Abstract
Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally driven atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/nonrocky transition in period-radius space. Here we present the confirmation of TOI-1235 b (P = 3.44 days, ${r}_{{\rm{p}}}={1.738}_{-0.076}^{+0.087}$ ${R}_{\oplus }$ ), a planet whose size and period are intermediate between the competing model predictions, thus making the system an important test case for emergence models of the rocky/nonrocky transition around early M dwarfs (Rs = 0.630 ± 0.015 ${R}_{\odot }$ , Ms = 0.640 ± 0.016 ${M}_{\odot }$ ). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high-resolution imaging, and a set of 38 precise radial velocities (RVs) from HARPS-N and HIRES. We measure a planet mass of ${6.91}_{-0.85}^{+0.75}$ ${M}_{\oplus }$ , which implies an iron core mass fraction of ${20}_{-12}^{+15}$ % in the absence of a gaseous envelope. The bulk composition of TOI-1235 b is therefore consistent with being Earth-like, and we constrain an H/He envelope mass fraction to be <0.5% at 90% confidence. Our results are consistent with model predictions from thermally driven atmospheric mass loss but not with gas-poor formation, suggesting that the former class of processes remains efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin ( $P={21.8}_{-0.8}^{+0.9}$ days, ${m}_{{\rm{p}}}\sin i={13.0}_{-5.3}^{+3.8}$ ${M}_{\oplus }$ ) that cannot be firmly ruled out by our data.
Volume
160
Issue
1
Start page
22
Issn Identifier
0004-6256
Ads BibCode
2020AJ....160...22C
Rights
open.access
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