The Astronomical Journal (Jan 2023)
Validation of TOI-1221 b: A Warm Sub-Neptune Exhibiting Transit Timing Variations around a Sun-like Star
- Christopher Mann,
- David Lafreniére,
- Diana Dragomir,
- Samuel N. Quinn,
- Thiam-Guan Tan,
- Karen A. Collins,
- Steve B. Howell,
- Carl Ziegler,
- Andrew W. Mann,
- Keivan G. Stassun,
- Martti H. Kristiansen,
- Hugh Osborn,
- Tabetha Boyajian,
- Nora Eisner,
- Coel Hellier,
- George R. Ricker,
- Roland Vanderspek,
- David W. Latham,
- S. Seager,
- Joshua N. Winn,
- Jon M. Jenkins,
- Jesus Noel Villaseñor,
- Brian McLean,
- Pamela Rowden,
- Guillermo Torres,
- Douglas A. Caldwell,
- Kevin I. Collins,
- Richard P. Schwarz
Affiliations
- Christopher Mann
- ORCiD
- Université de Montréal , Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montreal, QC, H2V 0B3, Canada ; [email protected]; Trottier Institute for Research on Exoplanets (iREx) , Montréal, of Physics, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montreal, QC, H2V 0B3, Canada
- David Lafreniére
- ORCiD
- Université de Montréal , Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montreal, QC, H2V 0B3, Canada ; [email protected]; Trottier Institute for Research on Exoplanets (iREx) , Montréal, of Physics, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montreal, QC, H2V 0B3, Canada
- Diana Dragomir
- ORCiD
- Department of Physics and Astronomy, University of New Mexico , 1919 Lomas Boulevard, NE Albuquerque, NM 87131, USA
- Samuel N. Quinn
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Thiam-Guan Tan
- ORCiD
- Perth Exoplanet Survey Telescope , Perth, Western Australia, Australia
- Karen A. Collins
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Steve B. Howell
- 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
- Andrew W. Mann
- ORCiD
- Department of Physics and Astronomy, The University of North Carolina at Chapel Hill , Chapel Hill, NC 27599-3255, USA
- Keivan G. Stassun
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , Nashville, TN 37235, USA
- Martti H. Kristiansen
- ORCiD
- Brorfelde Observatory , Observator Gyldenkernes Vej 7, DK-4340 Tølløse, Denmark
- Hugh Osborn
- Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA; Physikalisches Institut, University of Bern , Gesellsschaftstrasse 6, 3012 Bern, Switzerland
- Tabetha Boyajian
- ORCiD
- Louisiana State University , 202 Nicholson Hall, Baton Rouge, LA 70803, USA
- Nora Eisner
- ORCiD
- Sub-department of Astrophysics, University of Oxford , Keble Rd, OX1 3RH, Oxford, UK
- Coel Hellier
- ORCiD
- Astrophysics Group, Keele University , Staffordshire, ST5 5BG, UK
- George R. Ricker
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Roland Vanderspek
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- David W. Latham
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- S. Seager
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology , Cambridge, MA 02139, USA; Department of Aeronautics and Astronautics, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Joshua N. Winn
- ORCiD
- Department of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA
- Jon M. Jenkins
- ORCiD
- NASA Ames Research Center , Moffett Field, CA 94035, USA
- Jesus Noel Villaseñor
- ORCiD
- Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Brian McLean
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Pamela Rowden
- ORCiD
- Royal Astronomical Society , Burlington House, Piccadilly, London, W1J 0BQ, UK
- Guillermo Torres
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Douglas A. Caldwell
- ORCiD
- NASA Ames Research Center , Moffett Field, CA 94035, USA; SETI Institute , 339 Bernardo Ave, Mountain View, CA 94043, USA
- Kevin I. Collins
- ORCiD
- George Mason University , 4400 University Drive, Fairfax, VA 22030 USA
- Richard P. Schwarz
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- DOI
- https://doi.org/10.3847/1538-3881/acc8d4
- Journal volume & issue
-
Vol. 165,
no. 5
p. 217
Abstract
We present a validation of a long-period ( ${91.68278}_{-0.00041}^{+0.00032}$ days) transiting sub-Neptune planet, TOI-1221 b (TIC 349095149.01), around a Sun-like ( m _V = 10.5) star. This is one of the few known exoplanets with a period >50 days, and belongs to the even smaller subset of which have bright enough hosts for detailed spectroscopic follow-up. We combine Transiting Exoplanet Survey Satellite light curves and ground-based time-series photometry from the Perth Exoplanet Survey Telescope (0.3 m) and Las Cumbres Observatory global telescope network (1.0 m) to analyze the transit signals and rule out nearby stars as potential false-positive sources. High-contrast imaging from the Southern Astrophysical Research Telescope and Gemini/Zorro rule out nearby stellar contaminants. Reconnaissance spectroscopy from CHIRON sets a planetary scale upper mass limit on the transiting object (1.1 and 3.5 M _Jup at 1 σ and 3 σ , respectively) and shows no sign of a spectroscopic binary companion. We determine a planetary radius of ${R}_{{\rm{p}}}={2.91}_{-0.12}^{+0.13}{R}_{\oplus }$ , placing it in the sub-Neptune regime. With a stellar insolation of $S={6.06}_{-0.77}^{+0.85}\ {S}_{\oplus }$ , we calculate a moderate equilibrium temperature of T _eq = 440 K, assuming no albedo and perfect heat redistribution. We find a false-positive probability from the TRICERATOPS tool of FPP = 0.0014 ± 0.0003 as well as other qualitative and quantitative evidence to support the statistical validation of TOI-1221 b. We find significant evidence (>5 σ ) of oscillatory transit timing variations, likely indicative of an additional nontransiting planet.
Keywords
