TOI-6324 b: An Earth-mass Ultra-short-period Planet Transiting a Nearby M Dwarf

Abstract We report the confirmation of TOI-6324 b, an Earth-sized (1.059 ± 0.041 R ⊕ ) ultra-short-period (USP) planet orbiting a nearby (∼20 pc) M dwarf. Using the newly commissioned Keck Planet Finder spectrograph, we have measured the mass of TOI-6324 b 1.17 ± 0.22 M ⊕ . Because of its extremely short orbit of just ∼6.7 hr, TOI-6324 b is intensely irradiated by its M dwarf host and is expected to be stripped of any thick H/He envelope. We were able to constrain its interior composition and found an iron-core mass fraction (CMF = 27% ± 37%) consistent with that of Earth (∼33%) and other confirmed USPs. TOI-6324 b is the closest to an Earth-sized USP confirmed to date. TOI-6324 b is a promising target for JWST phase-curve and secondary eclipse observations (emission spectroscopy metric = 25), which may reveal its surface mineralogy, day–night temperature contrast, and possible tidal deformation. From seven sectors of TESS data, we report a tentative detection of the optical phase-curve variation with an amplitude of 42 ± 28 ppm.

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Publication Details

Journal
The Astrophysical Journal Letters
Published
2025-04-16
DOI
https://doi.org/10.3847/2041-8213/adadd7
Citations
1
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
1.15

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article

TOI-6324 b: An Earth-mass Ultra-short-period Planet Transiting a Nearby M Dwarf

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1 citations
The Astrophysical Journal Letters
Stellar, planetary, and galactic studies
1.15
article

TOI-6324 b: An Earth-mass Ultra-short-period Planet Transiting a Nearby M Dwarf

Joshua E. Schlieder, Michael Greklek-McKeon, Samuel Halverson, Howard Isaacson, Leslie A. Rogers, Matthew A. Brown, Jon M. Jenkins, Jack Lubin, J. M. Joel Ong, Abby P. Shaum, Andrew W. Howard, Jacob K. Luhn, Steven Giacalone, Kyle Lanclos, Corey Beard, Heather A. Knutson, Jonathan Gomez Barrientos, Joel Payne, Aaron Householder, Gautam Vasisht, Sherry Yeh, Daniel Huber, Karen A. Collins, Ian J. M. Crossfield, Casey L. Brinkman, Emily A. Gilbert, W. Garrett Levine, Arpita Roy, Benjamin J. Fulton, Renyu Hu, Sara Seager, Diana Valencia, Erik A. Petigura, Luke B. Handley, B. Holden, Max Brodheim, Daniel Hey, Christian Schwab, Johanna Teske, Martin M. Sirk, David Charbonneau, Te Han, Ashley Baker, Paul M. Robertson, Grant M. Hill, Steven R. Gibson, G. Ricker, Russ R. Laher, Gregory J. Gilbert, Kimberly Paragas, Mykhaylo Plotnykov, John M. O’Meara, Guđmundur Stefánsson, Judah Van Zandt, Alex S. Polanski, David R. Ciardi, Stephanie Striegel, Ryan A. Rubenzahl, William Deich, Rena A. Lee, Sharon X. Wang, Lauren M. Weiss, X. Dumusque, R. Vanderspek, Josh Walawender, Rae Holcomb, Kodi Rider, Nicholas Saunders, Jingwen Zhang, John Valliant, Stephen Kaye, Edward Wishnow, Joshua N. Winn, Fei Dai
article en
1 citations

Abstract

Abstract We report the confirmation of TOI-6324 b, an Earth-sized (1.059 ± 0.041 R ⊕ ) ultra-short-period (USP) planet orbiting a nearby (∼20 pc) M dwarf. Using the newly commissioned Keck Planet Finder spectrograph, we have measured the mass of TOI-6324 b 1.17 ± 0.22 M ⊕ . Because of its extremely short orbit of just ∼6.7 hr, TOI-6324 b is intensely irradiated by its M dwarf host and is expected to be stripped of any thick H/He envelope. We were able to constrain its interior composition and found an iron-core mass fraction (CMF = 27% ± 37%) consistent with that of Earth (∼33%) and other confirmed USPs. TOI-6324 b is the closest to an Earth-sized USP confirmed to date. TOI-6324 b is a promising target for JWST phase-curve and secondary eclipse observations (emission spectroscopy metric = 25), which may reveal its surface mineralogy, day–night temperature contrast, and possible tidal deformation. From seven sectors of TESS data, we report a tentative detection of the optical phase-curve variation with an amplitude of 42 ± 28 ppm.

The Astrophysical Journal LettersVol. 983(2)
University of Notre Dame (US), University of Geneva (CH), California Institute of Technology (US), Ames Research Center (US), Goddard Space Flight Center (US), University of Hawaii System (US), Jet Propulsion Laboratory (US), University of Kansas (US), University of California, Los Angeles (US), University of California, Santa Cruz (US), University of Toronto (CA), University of Southern Queensland (AU), Carnegie Institution for Science (US), Princeton University (US), University of California, Irvine (US), Lowell Observatory (US), W.M. Keck Observatory (US), NASA Exoplanet Science Institute (US), Yale University (US), University of Chicago (US), Center for Astrophysics Harvard & Smithsonian (US), Flatiron Health (United States) (US), Flatiron Institute (US), American Institute of Aeronautics and Astronautics (US), Massachusetts Institute of Technology (US), University of Amsterdam (NL), University of California, Berkeley (US), Macquarie University (AU), Tsinghua University (CN)
National Science Foundation, National Aeronautics and Space Administration, W. M. Keck Foundation, California Institute of Technology, Space Telescope Science Institute, NASA Exoplanet Science Institute, Nuclear Safety and Security Commission, Ames Research Center, Jet Propulsion Laboratory, Science Mission Directorate
Openalex Percentile: Top 20%
Stellar, planetary, and galactic studies
1.15
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