Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TESS and CHEOPS

Shishir Dholakia*, Larissa Palethorpe*, Alexander Venner, Annelies Mortier, Thomas G Wilson, Chelsea X Huang, Ken Rice, Vincent Van Eylen, Emma Nabbie, Ryan Cloutier, Walter Boschin, David Ciardi, Laetitia Delrez, Georgina Dransfield, Elsa Ducrot, Zahra Essack, Mark E Everett, Michaël Gillon, Matthew J Hooton, Michelle KunimotoDavid W Latham, Mercedes López-Morales, Bin Li, Fan Li, Scott McDermott, Simon J Murphy, Catriona A Murray, Sara Seager, Mathilde Timmermans, Amaury Triaud, Daisy A Turner, Joseph D Twicken, Andrew Vanderburg, Su Wang, Robert A Wittenmyer, Duncan Wright

*Corresponding author for this work

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Abstract

We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors 42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory, as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of 12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
Original languageEnglish
Pages (from-to)1276-1293
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume531
Issue number1
Early online date23 May 2024
DOIs
Publication statusPublished - Jun 2024

Keywords

  • planets and satellites: detection
  • planets and satellites: terrestrial planets
  • techniques: photometric
  • stars: individual: Gliese 12
  • planets and satellites: individual: Gliese 12 b

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