The Astronomical Journal (Jan 2024)
GJ 238 b: A 0.57 Earth Radius Planet Orbiting an M2.5 Dwarf Star at 15.2 pc
- Evan Tey,
- Avi Shporer,
- Zifan Lin,
- Keivan G. Stassun,
- Jack J. Lissauer,
- Coel Hellier,
- Karen A. Collins,
- Kevin I. Collins,
- Geof Wingham,
- Howard M. Relles,
- Franco Mallia,
- Giovanni Isopi,
- John F. Kielkopf,
- Dennis M. Conti,
- Richard P. Schwarz,
- Aldo Zapparata,
- Steven Giacalone,
- Elise Furlan,
- Zachary D. Hartman,
- Steve B. Howell,
- Nicholas J. Scott,
- Carl Ziegler,
- César Briceño,
- Nicholas Law,
- Andrew W. Mann,
- David Charbonneau,
- Zahra Essack,
- Stephanie Striegel,
- George R. Ricker,
- Roland Vanderspek,
- Sara Seager,
- Joshua N. Winn,
- Jon M. Jenkins
Affiliations
- Evan Tey
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Science , Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; [email protected]
- Avi Shporer
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Science , Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; [email protected]
- Zifan Lin
- ORCiD
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Keivan G. Stassun
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , Nashville, TN 37235, USA; Department of Physics, Fisk University , Nashville, TN 37208, USA
- Jack J. Lissauer
- ORCiD
- NASA Ames Research Center , Moffett Field, CA 94035, USA
- Coel Hellier
- ORCiD
- Astrophysics Group, Keele University , Staffordshire ST5 5BG, UK
- Karen A. Collins
- ORCiD
- Center for Astrophysics ∣Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Kevin I. Collins
- ORCiD
- George Mason University , 4400 University Drive, Fairfax, VA 22030, USA
- Geof Wingham
- Mt. Stuart Observatory , New Zealand
- Howard M. Relles
- Center for Astrophysics ∣Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Franco Mallia
- ORCiD
- Campo Catino Astronomical Observatory , Regione Lazio, Guarcino (FR), 03010, Italy
- Giovanni Isopi
- Campo Catino Astronomical Observatory , Regione Lazio, Guarcino (FR), 03010, Italy
- John F. Kielkopf
- ORCiD
- Department of Physics and Astronomy, University of Louisville , Louisville, KY 40292, USA
- Dennis M. Conti
- ORCiD
- American Association of Variable Star Observers , 185 Alewife Brook Parkway, Suite 410, Cambridge, MA 02138, USA
- Richard P. Schwarz
- ORCiD
- Center for Astrophysics ∣Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Aldo Zapparata
- ORCiD
- Campo Catino Astronomical Observatory , Regione Lazio, Guarcino (FR), 03010, Italy
- Steven Giacalone
- ORCiD
- Department of Astronomy, California Institute of Technology , Pasadena, CA 91125, USA
- Elise Furlan
- ORCiD
- Caltech/IPAC-NASA Exoplanet Science Institute , 770 S. Wilson Avenue, Pasadena, CA 91106, USA
- Zachary D. Hartman
- ORCiD
- Gemini Observatory/NSF's NOIRLab , 670 A’ohoku Place, Hilo, HI 96720, USA
- Steve B. Howell
- ORCiD
- NASA Ames Research Center , Moffett Field, CA 94035, USA
- Nicholas J. Scott
- ORCiD
- NASA Ames Research Center , Moffett Field, CA 94035, USA
- Carl Ziegler
- Department of Physics, Engineering and Astronomy, Stephen F. Austin State University , 1936 North Street, Nacogdoches, TX 75962, USA
- César Briceño
- ORCiD
- Cerro Tololo Inter-American Observatory/NSF's NOIRLab , Casilla 603, La Serena 1700000, Chile
- Nicholas Law
- ORCiD
- Department of Physics and Astronomy, The University of North Carolina at Chapel Hill , Chapel Hill, NC 27599-3255, USA
- Andrew W. Mann
- ORCiD
- Department of Physics and Astronomy, The University of North Carolina at Chapel Hill , Chapel Hill, NC 27599-3255, USA
- David Charbonneau
- ORCiD
- Center for Astrophysics ∣Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Zahra Essack
- ORCiD
- Department of Physics and Astronomy, The University of New Mexico , 210 Yale Boulevard NE, Albuquerque, NM 87106, USA
- Stephanie Striegel
- ORCiD
- NASA Ames Research Center , Moffett Field, CA 94035, USA; SETI Institute , Mountain View, CA 94043, USA
- George R. Ricker
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Science , Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; [email protected]
- Roland Vanderspek
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Science , Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; [email protected]
- Sara Seager
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Science , Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; [email protected]; Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology , Cambridge, MA 02139, USA; Department of Aeronautics and Astronautics, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Joshua N. Winn
- ORCiD
- Department of Astrophysical Sciences, Princeton University , Princeton, NJ 08544, USA
- Jon M. Jenkins
- ORCiD
- NASA Ames Research Center , Moffett Field, CA 94035, USA
- DOI
- https://doi.org/10.3847/1538-3881/ad3df1
- Journal volume & issue
-
Vol. 167,
no. 6
p. 283
Abstract
We report the discovery of the transiting planet GJ 238 b, with a radius of 0.566 ± 0.014 R _⊕ (1.064 ± 0.026 times the radius of Mars) and an orbital period of 1.74 days. The transit signal was detected by the TESS mission and designated TOI-486.01. The star’s position close to the southern ecliptic pole allows for almost continuous observations by TESS when it is observing the southern sky. The host star is an M2.5 dwarf with V = 11.57 ± 0.02 mag, K = 7.030 ± 0.023 mag, a distance of 15.2156 ± 0.0030 pc, a mass of ${0.4193}_{-0.0098}^{+0.0095}$ M _☉ , a radius of ${0.4314}_{-0.0071}^{+0.0075}$ R _☉ , and an effective temperature of 3485 ± 140 K. We validate the planet candidate by ruling out or rendering highly unlikely each of the false positive scenarios, based on archival data and ground-based follow-up observations. Validation was facilitated by the host star’s small size and high proper motion of 892.633 ± 0.025 mas yr ^–1 .
Keywords
