Early Results from the HUMDRUM Survey: A Small, Earth-mass Planet Orbits TOI-1450A

Madison Brady, Jacob L. Bean, Andreas Seifahrt, David Kasper, Rafael Luque, Guđmundur Stefánsson, Julian Stürmer, David Charbonneau, Karen A. Collins, John P. Doty, Zahra Essack, Akihiko Fukui, Ferran Grau Horta, Christina Hedges, Coel Hellier, Jon M. Jenkins, Norio Narita, Samuel N. Quinn, Avi Shporer, Richard P. SchwarzSara Seager, Keivan G. Stassun, Stephanie Striegel, Cristilyn N. Watkins, Joshua N. Winn, Roberto Zambelli

Research output: Contribution to journalArticlepeer-review

Abstract

M-dwarf stars provide us with an ideal opportunity to study nearby small planets. The HUnting for M Dwarf Rocky planets Using MAROON-X (HUMDRUM) survey uses the MAROON-X spectrograph, which is ideally suited to studying these stars, to measure precise masses of a volume-limited (<30 pc) sample of transiting M-dwarf planets. TOI-1450 is a nearby (22.5 pc) binary system containing a M3 dwarf with a roughly 3000 K companion. Its primary star, TOI-1450A, was identified by the Transiting Exoplanet Survey Satellite (TESS) to have a 2.04 days transit signal, and is included in the HUMDRUM sample. In this paper, we present MAROON-X radial velocities (RVs) which confirm the planetary nature of this signal and measure its mass at nearly 10% precision. The 2.04 days planet, TOI-1450A b, has R b = 1.13 ± 0.04 R and M b = 1.26 ± 0.13 M . It is the second-lowest-mass transiting planet with a high-precision RV mass measurement. With this mass and radius, the planet’s mean density is compatible with an Earth-like composition. Given its short orbital period and slightly sub-Earth density, it may be amenable to JWST follow-up to test whether the planet has retained an atmosphere despite extreme heating from the nearby star. We also discover a nontransiting planet in the system with a period of 5.07 days and a M sin i c = 1.53 ± 0.18 M ⊕ . We also find a 2.01 days signal present in the systems’s TESS photometry that likely corresponds to the rotation period of TOI-1450A’s binary companion, TOI-1450B. TOI-1450A, meanwhile, appears to have a rotation period of approximately 40 days, which is in line with our expectations for a mid-M dwarf.

Original languageEnglish (US)
Article number67
JournalAstronomical Journal
Volume168
Issue number2
DOIs
StatePublished - Aug 1 2024

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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