TESS discovery of a super-Earth and two sub-Neptunes orbiting the bright, nearby, Sun-like star HD 22946

¹ Department of Physics “Ettore Pancini”, University of Naples, Federico II, 80138 Napoli NA, Italy
e-mail: luca.cacciapuoti@eso.org
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Munchen, Germany
³ Science and Technology Department, Parthenope University of Naples, CDN IC4, 80143 Napoli, Italy
⁴ INAF-Osservatorio Astronomico di Capodimonte, Salita Moraliello, 16, 80131 Napoli, Italy
⁵ INFN, Sezione di Napoli, Strada Comunale Cinthia, 80126 Napoli NA, Italy
⁶ NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory (Code 667), Greenbelt, MD 20771, USA
⁷ Vanderbilt University, Department of Physics & Astronomy, 6301 Stevenson Center Lane, Nashville, TN 37235, USA
⁸ Fisk University, Department of Physics, 1000 18th Avenue N., Nashville, TN 37208, USA
⁹ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
¹⁰ Department of Astronomy, University of California Berkeley, Berkeley, CA 94720-3411, USA
¹¹ Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA
¹² SETI Institute, 189 Bernardo Ave, Suite 200, Mountain View, CA 94043, USA
¹³ Department of Physics and Astronomy, Bishops University 2600 College St, Sherbrooke, QC J1M 1Z7, Canada
¹⁴ Tsinghua International School, Beijing 100084, PR China
¹⁵ George Mason University, 4400 University Drive, Fairfax, VA 22030 USA
¹⁶ Center for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
¹⁷ Perth Exoplanet Survey Telescope, Perth, Western Australia, Australia
¹⁸ Departamento de Matemática y Física Aplicadas, Facultad de Ingeniería, Universidad Católica de la Santísima Concepción, Alonso de Rivera 2850, Concepción, Chile
¹⁹ Caltech/IPAC-NASA Exoplanet Science Institute, 770 S. Wilson Avenue, Pasadena, CA 91106, USA
²⁰ NASA Exoplanet Science Institute, Caltech/IPAC, Mail Code 10022, 1200 E. California Blvd., Pasadena, CA 91125, USA
²¹ NASA Ames Research Center, Moffett Field, CA 94035, USA
²² Department of Physics, Engineering and Astronomy, Stephen F. Austin State University, 1936 North St, Nacogdoches, TX 75962, USA
²³ Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
²⁴ Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255, USA
²⁵ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 3902139, USA
²⁶ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
²⁷ Institute of Space Astrophysics and Planetology INAF-IAPS, Via Fosso del Cavaliere 100, 00133 Rome, Italy
²⁸ Western Connecticut State University, 181 White Street, Danbury, CT 06810, USA
²⁹ Department of Astronomy and Carl Sagan Institute, Cornell University, 122 Sciences Drive, Ithaca, NY 14853, USA
³⁰ Proto-Logic LLC, 1718 Euclid Street NW, Washington, DC 20009, USA
³¹ Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³² Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³³ SETI Institute, Mountain View, CA 94043, USA
³⁴ Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
³⁵ Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³⁶ Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³⁷ University of Southern Queensland, Centre for Astrophysics, West Street, Toowoomba, QLD 4350 Australia
³⁸ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³⁹ Curtin Institute of Radio Astronomy, Curtin University, Bentley, Western Australia 6102, Australia
⁴⁰ Department of Physics and Astronomy, University of New Mexico, 210 Yale Blvd NE, Albuquerque, NM 87106, USA
⁴¹ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
⁴² University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA

Received: 16 March 2022
Accepted: 14 September 2022

Abstract

We report the Transiting Exoplanet Survey Satellite (TESS) discovery of a three-planet system around the bright Sun-like star HD 22946 (V ≈ 8.3 mag), also known as TIC 100990000, located 63 pc from Earth. The system was observed by TESS in Sectors 3, 4, 30, and 31 and two planet candidates, labeled TESS Objects of Interest (TOIs) 411.01 (planet c) and 411.02 (planet b), were identified on orbits of 9.57 and 4.04 days, respectively. In this work, we validate the two planets and recover an additional single transit-like signal in the light curve, which suggests the presence of a third transiting planet with a longer period of about 46 days. We assess the veracity of the TESS transit signals and use follow-up imaging and time-series photometry to rule out false-positive scenarios, including unresolved binary systems, nearby eclipsing binaries, and contamination of the light curves by background or foreground stars. Parallax measurements from Gaia Early Data Release 3 together with broad-band photometry and spectroscopic follow-up by the TESS FollowUp Observing Program (TFOP) allowed us to constrain the stellar parameters of TOI-411, including its radius of 1.157 ± 0.025 R_⊙. Adopting this value, we determined the radii for the three exoplanet candidates and found that planet b is a super-Earth with a radius of 1.48 ± 0.06 R_⊕, while planets c and d are sub-Neptunian planets with radii of 2.35 ± 0.08 R_⊕ and 2.78 ± 0.13 R_⊕ respectively. Using dynamical simulations, we assessed the stability of the system and evaluated the possibility of the presence of other undetected, non-transiting planets by investigating its dynamical packing. We find that the system is dynamically stable and potentially unpacked, with enough space to host at least one more planet between c and d. Finally, given that the star is bright and nearby, we discuss possibilities for detailed mass characterisation of its surrounding worlds and opportunities for the detection of their atmospheres with the James Webb Space Telescope.