The TESS-Keck Survey. II. An Ultra-short-period Rocky Planet and Its Siblings Transiting the Galactic Thick-disk Star TOI-561

Weiss, Lauren M.; Dai, Fei; Huber, Daniel; Brewer, John M.; Collins, Karen A.; Ciardi, David R.; Matthews, Elisabeth C.; Ziegler, Carl; Howell, Steve B.; Batalha, Natalie M.; Crossfield, Ian J. M.; Dressing, Courtney D.; Fulton, B. J.; Howard, Andrew W.; Isaacson, Howard; Kane, Stephen R.; Petigura, Erik A.; Robertson, Paul; Roy, Arpita; Rubenzahl, Ryan A.; Twicken, Joseph D.; Claytor, Zachary R.; Stassun, Keivan G.; MacDougall, Mason G.; Chontos, Ashley; Giacalone, Steven; Dalba, Paul A.; Močnik, Teo; Hill, Michelle L.; Beard, Corey; Murphy, Joseph M. Akana; Rosenthal, Lee J.; Behmard, Aida; Zandt, Judah Van; Polanski, Alex S.; Kosiarek, Molly R.; Lund, Michael B.; Christiansen, Jessie L.; Matson, Rachel A.; Beichman, Charles; Schlieder, Joshua E.; Gonzales, Erica J.; Briceño, César; Law, Nicholas M.; Mann, Andrew W.; Collins, Kevin I.; Evans, P.; Fukui, A.; Jensen, Eric L. N.; Murgas, F.; Narita, Norio; Πάλλη, Ε.; Parviainen, H.; Schwarz, Richard P.; Tan, T. G.; Acton, Jack S.; Bryant, Edward M.; Chaushev, Alexander; Gill, Samuel; Eigmüller, Philipp; Jenkins, Jon M.; Ricker, G.; Seager, Sara; Winn, Joshua N.

doi:10.3847/1538-3881/abd409

Cited by 40 publications

(40 citation statements)

References 121 publications

(119 reference statements)

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“…Examples of such recent discoveries from TESS include the TOI-561 system (Lacedelli et al 2021;Weiss et al 2020), TOI-130 system (Sozzetti et al 2021), and TOI-178 system (Leleu et al 2021).…”

Section: Introductionmentioning

confidence: 99%

New Perspectives on the Exoplanet Radius Gap from a Mathematica Tool and Visualized Water Equation of State

Zeng

Jacobsen

Hyung

et al. 2021

ApJ

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Recent astronomical observations obtained with the Kepler and TESS missions and their related ground-based follow-ups revealed an abundance of exoplanets with a size intermediate between Earth and Neptune (1 R ⊕ ≤ R ≤ 4 R ⊕). A low occurrence rate of planets has been identified at around twice the size of Earth (2 × R ⊕), known as the exoplanet radius gap or radius valley. We explore the geometry of this gap in the mass–radius diagram, with the help of a Mathematica plotting tool developed with the capability of manipulating exoplanet data in multidimensional parameter space, and with the help of visualized water equations of state in the temperature–density (T–ρ) graph and the entropy–pressure (s–P) graph. We show that the radius valley can be explained by a compositional difference between smaller, predominantly rocky planets (<2 × R ⊕) and larger planets (>2 × R ⊕) that exhibit greater compositional diversity including cosmic ices (water, ammonia, methane, etc.) and gaseous envelopes. In particular, among the larger planets (>2 × R ⊕), when viewed from the perspective of planet equilibrium temperature (T eq), the hot ones (T eq ≳ 900 K) are consistent with ice-dominated composition without significant gaseous envelopes, while the cold ones (T eq ≲ 900 K) have more diverse compositions, including various amounts of gaseous envelopes.

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Section: Introductionmentioning

confidence: 99%

New Perspectives on the Exoplanet Radius Gap from a Mathematica Tool and Visualized Water Equation of State

Zeng

Jacobsen

Hyung

et al. 2021

ApJ

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“…TKS is a consortium performing precise RV (PRV) followup of TESS planet candidates (Dalba et al 2020;Dai et al 2020;Rubenzahl et al 2021;Weiss et al 2021). One of our group's primary science goals is to measure a diverse set of planet masses at high enough precision to be suitable for atmospheric characterization (Batalha et al 2019), particularly with the James Webb Space Telescope (JWST), which is what led us to observe HD 63935.…”

Section: Introductionmentioning

confidence: 99%

“…Because of their relatively small transit signals, such planets represent more challenging targets than similar-sized targets around M or K dwarfs. However, the brightness of the host stars can compensate for this, and a number of compelling targets for atmospheric characterization with JWST around G star hosts have already emerged from TESS (e.g., Gandolfi et al 2018;Mann et al 2020;Weiss et al 2021, Lubin et al 2021Turtelboom et al 2021, in preparation).…”

Section: Introductionmentioning

confidence: 99%

TESS-Keck Survey. V. Twin Sub-Neptunes Transiting the Nearby G Star HD 63935

Scarsdale

Murphy

Batalha

et al. 2021

Self Cite

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We present the discovery of two nearly identically sized sub-Neptune transiting planets orbiting HD 63935, a bright (V = 8.6 mag), Sun-like (T eff = 5560 K) star at 49 pc. TESS identified the first planet, HD 63935 b (TOI-509.01), 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

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“…Specifically, Winn et al (2018) found that the radius distribution of USP planets shows a decline at a physical radius of 2 R ⊕ , indicating that USP planets tend to be small (despite discovery biases against smaller planets). Although only a limited number of USP planets have measurements of both their mass and radius, and their densities are largely consistent with rocky compositions (e.g., Grunblatt et al 2015;Weiss et al 2016;Christiansen et al 2017;Sinukoff et al 2017;Vanderburg et al 2017;Weiss et al 2021), and they often reside in multiplanet systems (Winn et al 2018;Adams et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Migrating Planets into Ultra-short-period Orbits during Episodic Accretion Events

Becker

Batygin

Adams

2021

ApJ

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Ultra-short-period (USP) planets reside inside the expected truncation radius for typical T Tauri disks. As a result, their current orbital locations require an explanation beyond standard disk migration or in situ formation. Modern theories of planet-disk interactions indicate that once a planet migrates close to the disk's inner truncation radius, Type I torques vanish or switch direction, depending on the stellar and disk conditions, so that the planet is expected to stop its orbital decay and become trapped. In this work, we show that that magnetically driven sub-Keplerian gas flow in the inner disk can naturally counteract these effects and produce systems with USP planets at their observed orbital radii. The sub-Keplerian gas flow provides a headwind to small planets, and the resulting torque can overcome the effects of outward Type I migration near the corotation radius. For suitable disk and planet parameters, the torques due to the sub-Keplerian gas flow lead to inward migration on a rapid timescale. Over the time span of an FU Ori outburst, which moves the disk truncation radius inward, the rapid headwind migration can place planets in USP orbits. The combination of headwind migration and FU Ori outbursts thus provides a plausible mechanism to move small planets from a = 0.05-0.1 au down to a = 0.01-0.02 au. This effect is amplified for low-mass planets, consistent with existing observations.

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The TESS-Keck Survey. II. An Ultra-short-period Rocky Planet and Its Siblings Transiting the Galactic Thick-disk Star TOI-561

Abstract: We report the discovery of TOI-561, a multiplanet system in the galactic thick disk that contains a rocky, ultrashort-period planet. This bright (V = 10.2) star hosts three small transiting planets identified in photometry from the NASA TESS mission: TOI-561 b (TOI-561.02,

Cited by 40 publications

References 121 publications

New Perspectives on the Exoplanet Radius Gap from a Mathematica Tool and Visualized Water Equation of State

New Perspectives on the Exoplanet Radius Gap from a Mathematica Tool and Visualized Water Equation of State

TESS-Keck Survey. V. Twin Sub-Neptunes Transiting the Nearby G Star HD 63935

Migrating Planets into Ultra-short-period Orbits during Episodic Accretion Events

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