Year: 2026
Type: preprint
Abstract: We present TOI-6981 b, a cold (Teq= 175^{+6}_{-5} K, assuming an Earth-like albedo) sub-Neptune (Rb=2.51+/-0.11 R_oplus) orbiting on a 60.8 day orbit around around its M4-type host star (R*=0.304 +/- 0.012 R_odot, M*=0.296 +/- 0.026 M_odot, Teff = 3215+/-58K), part of the SPECULOOS TEMPOS program. We validate the planetary nature of TOI-6981 b using ground-based follow-up photometry, statistical validation and high-resolution spectroscopy. At such cold temperatures, TOI-6981 b sits roughly at the location of the water ice line (approx 170 K). Given its orbital period and high transmission spectroscopy metric (TSM=56 +/- 10), it is one of the only planets in the sparsely populated cold planet regime amenable for atmospheric studies with JWST. Therefore, TOI-6981 b could. possibly become a crucial benchmark in cold chemistry studies, tests of Hycean world hypotheses, and drawling parallels to the Solar System's ice giants. Additionally, given its current orbit, it may provide insight into planetary formation and migration at or beyond the water ice line.
Source: arXiv (Cornell University)
Authors: Scott, Madison G., Triaud, Amaury H. M. J, Pass, Emily K., Adamson, Aleyna, Collins, Karen A., Barkaoui, Khalid, Bieryla, Allyson, Burgasser, Adam J., Everett, Mark E., Howell, Steve B., Latham, David W., Rackham, Benjamin V., Safonov, Boris S., Serra-Ricart, Miquel, Soubkiou, Abderahmane, Dransfield, Georgina, Hesse, Katharine, de Diego, Pipa Fernandez, Softich, Emma, Srdoc, Gregor, Timmermans, Mathilde, Audenaert, Jeroen, Alonso, Roi, Burdanov, Artem Y., Davis, Yasmin T., Davoudi, Fatemeh, de Wit, Julien, Dholakia, Shishir, Ducrot, Elsa, Gillon, Michaël, Chew, Yilen Gomez Maqueo, Hooton, Matthew J., Janó-Muñoz, Clàudia, Jehin, Emmanuel, Khandelwal, Akanksha, Marriott, Thomas R., Pedersen, Peter P., Marcano, Manuel Pichardo, Pozuelos, Francisco J., Rebolo-López, Rafael, Stalport, Manu, Venner, Alexander, Yalçinkaya, Selçuk, Lang, Francis Zong, Zúñiga-Fernández, Sebastián
Institutions: University of Birmingham, Massachusetts Institute of Technology, Center for Astrophysics Harvard & Smithsonian, University of California San Diego, NSF NOIRLab, Ames Research Center, Lomonosov Moscow State University, University of Liège, Universidad de La Laguna, Instituto de Astrofísica de Canarias, University of Southern Queensland, Centre National de la Recherche Scientifique, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, Astrophysique, Instrumentation et Modélisation, University of Cambridge, Universidad Nacional Autónoma de México, ETH Zurich, Institute for Particle Physics and Astrophysics, Instituto de Astrofísica de Andalucía, Max Planck Institute for Astronomy, University of Bern, Center for Space and Habitability
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, UK Research and Innovation, Ministerio de Ciencia, Innovación y Universidades, European Commission, University of Birmingham, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Fonds De La Recherche Scientifique - FNRS, Ministry of Science, ICT and Future Planning, Ministerio de Ciencia e Innovación, Fondation Merac, Instituto de Astrofísica de Canarias, Science Mission Directorate, Science and Technology Facilities Council, Agencia Estatal de Investigación
Awards: G101150294, G121809054, G1272900390, G1288897701, G13101216, An upgrade to the mount of the ASTEP telescope, G1381791653, G1814045685, G1853635042, Red-enhanced cameras to seek rocky planets transiting Ultra-Cool Dwarfs, G2309174360, G2459365730, G2579336268, G2660406951, G3106129878, G322776270, G3228472174, G3453057146, G3518538256, G3696727022, G373897614, G4126913923, G4212894969, G4334099265, G4408153509, G463062595, G5059192377, G5404395142, G5635532810, G5811331711, G5881647929, G5894067328, Discovering and probing the atmospheres of rocky exoplanets, G6201089904, Temperate exoplanets from Chile & Antarctica, G6686480456, Discovering and probing the atmospheres of rocky exoplanets, G7075130942, G7276812026, G745419941, G748919333, G7518687652, G7719629023, G7805626310, G8211471405, Alexander von Humboldt and the Globalization of Science: Networks of Knowledge between Germany and the United States in the 19th Century, Characterization of the expression of Retinoic acid receptor during early chick development, G8597195001, G8827130585, G8920660035, G897484643
OpenAlex ID: W7214963695