Teegarden’s Star revisited

A nearby planetary system with at least three planets^★,★★

¹ Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
e-mail: dreizler@astro.physik.uni-goettingen.de
² Department of Astronomy & Astrophysics, University of Chicago, Chicago, IL 60637, USA
³ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁴ Institut de Ciències de l’Espai (ICE, CSIC), Campus UAB, C/ Can Magrans s/n, 08193 Bellaterra, Spain
⁵ Institut d’Estudis Espacials de Catalunya, C/ Gran Capità, 2–4, 08028 Barcelona, Spain
⁶ Astrobiology Research Unit, Université de Liège, 19C Allée du 6 Août, 4000 Liège, Belgium
⁷ Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium
⁸ Centro de Astrobiología (CSIC-INTA), ESAC campus, Camino bajo del castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
⁹ Instituto de Astrofísica de Canarias, Av. Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
¹⁰ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
¹¹ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
¹² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹³ Departamento de Física de la Tierra y Astrofísica and IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040, Madrid, Spain
¹⁴ Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
¹⁵ Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
¹⁶ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
¹⁷ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08540, USA
¹⁸ Centro Astronónomico Hispano en Andalucía, Observatorio de Calar Alto, Sierra de los Filabres, 04550 Gérgal, Almería, Spain

Received: 21 September 2023
Accepted: 15 January 2024

Abstract

The two known planets in the planetary system of Teegarden’s Star are among the most Earth-like exoplanets currently known. Revisiting this nearby planetary system with two planets in the habitable zone aims at a more complete census of planets around very low-mass stars. A significant number of new radial velocity measurements from CARMENES, ESPRESSO, MAROON-X, and HPF, as well as photometry from TESS motivated a deeper search for additional planets. We confirm and refine the orbital parameters of the two know planets Teegarden’s Star b and c. We also report the detection of a third planet d with an orbital period of 26.13 ± 0.04 days and a minimum mass of 0.82 ± 0.17 M_⊕. A signal at 96 days is attributed to the stellar rotation period. The interpretation of a signal at 172 days remains open. The TESS data exclude transiting short-period planets down to about half an Earth radius. We compare the planetary system architecture of very low-mass stars. In the currently known configuration, the planetary system of Teegarden’s star is dynamically quite different from that of TRAPPIST-1, which is more compact, but dynamically similar to others such as GJ 1002.