A 1.55 R habitable-zone planet hosted by TOI-715, an M4 star near the ecliptic South Pole

Georgina Dransfield, Mathilde Timmermans, Amaury H.M.J. Triaud, Martín Dévora-Pajares, Christian Aganze, Khalid Barkaoui, Adam J. Burgasser, Karen A. Collins, Marion Cointepas, Elsa Ducrot, Maximilian N. Günther, Steve B. Howell, Catriona A. Murray, Prajwal Niraula, Benjamin V. Rackham, Daniel Sebastian, Keivan G. Stassun, Sebastián Zúñiga-Fernández, José Manuel Almenara, Xavier BonfilsFrançois Bouchy, Christopher J. Burke, David Charbonneau, Jessie L. Christiansen, Laetitia Delrez, Tianjun Gan, Lionel J. García, Michaël Gillon, Yilen Gómez Maqueo Chew, Katharine M. Hesse, Matthew J. Hooton, Giovanni Isopi, Emmanuël Jehin, Jon M. Jenkins, David W. Latham, Franco Mallia, Felipe Murgas, Peter P. Pedersen, Francisco J. Pozuelos, Didier Queloz, David R. Rodriguez, Nicole Schanche, Sara Seager, Gregor Srdoc, Chris Stockdale, Joseph D. Twicken, Roland Vanderspek, Robert Wells, Joshua N. Winn, Julien de Wit, Aldo Zapparata

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

A new generation of observatories is enabling detailed study of exoplanetary atmospheres and the diversity of alien climates, allowing us to seek evidence for extraterrestrial biological and geological processes. Now is therefore the time to identify the most unique planets to be characterized with these instruments. In this context, we report on the discovery and validation of TOI-715 b, a Rb = 1.55 ± 0.06R planet orbiting its nearby (42 pc) M4 host (TOI-715/TIC 271971130) with a period Pb = 19.288004+−00000024000027 d. TOI-715 b was first identified by TESS and validated using ground-based photometry, high-resolution imaging and statistical validation. The planet’s orbital period combined with the stellar effective temperature Teff = 3075 ± 75 K give this planet an installation Sb = 0.67+−002015 S, placing it within the most conservative definitions of the habitable zone for rocky planets. TOI-715 b’s radius falls exactly between two measured locations of the M-dwarf radius valley; characterizing its mass and composition will help understand the true nature of the radius valley for low-mass stars. We demonstrate TOI-715 b is amenable for characterization using precise radial velocities and transmission spectroscopy. Additionally, we reveal a second candidate planet in the system, TIC 271971130.02, with a potential orbital period of P02 = 25.60712+−000003600031 d and a radius of R02 = 1.066 ± 0.092 R, just inside the outer boundary of the habitable zone, and near a 4:3 orbital period commensurability. Should this second planet be confirmed, it would represent the smallest habitable zone planet discovered by TESS to date.

Original languageEnglish (US)
Pages (from-to)35-52
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume527
Issue number1
DOIs
StatePublished - Jan 1 2024

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • planets
  • planets and satellites: detection
  • planets and satellites: fundamental parameters
  • satellites: terrestrial planets

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