The cool brown dwarf Gliese 229 B is a close binary

• 成果类型: Article
• 署名作者: Xuan, Jerry W.; Merand, A.; Thompson, W.; Zhang, Y.; Lacour, S.; Blakely, D.; Mawet, D.; Oppenheimer, R.; Kammerer, J.; Batygin, K.; Sanghi, A.; Wang, J.; Ruffio, J. -B.; Liu, M. C.; Knutson, H.; Brandner, W.; Burgasser, A.; Rickman, E.; Bowens-Rubin, R.; Salama, M.; Balmer, W.; Blunt, S.; Bourdarot, G.; Caselli, P.; Chauvin, G.; Davies, R.; Drescher, A.; Eckart, A.; Eisenhauer, F.; Fabricius, M.; Feuchtgruber, H.; Finger, G.; Schreiber, N. M. Foerster; Garcia, P.; Genzel, R.; Gillessen, S.; Grant, S.; Hartl, M.; Haussmann, F.; Henning, T.; Hinkley, S.; Honig, S. F.; Horrobin, M.; Houlle, M.; Janson, M.; Kervella, P.; Kral, Q.; Kreidberg, L.; Le Bouquin, J. -B.; Lutz, D.; Mang, F.; Marleau, G. -D.; Millour, F.; More, N.; Nowak, M.; Ott, T.; Otten, G.; Paumard, T.; Rabien, S.; Rau, C.; Ribeiro, D. C.; Bordoni, M. Sadun; Sauter, J.; Shangguan, J.; Shimizu, T. T.; Sykes, C.; Soulain, A.; Spezzano, S.; Straubmeier, C.; Stolker, T.; Sturm, E.; Subroweit, M.; Tacconi, L. J.; van Dishoeck, E. F.; Vigan, A.; Widmann, F.; Wieprecht, E.; Winterhalder, T. O.; Woillez, J.
• 署名单位: California Institute of Technology; European Southern Observatory; University of Victoria; Centre National de la Recherche Scientifique (CNRS); Universite PSL; Observatoire de Paris; Universite Paris Cite; Sorbonne Universite; National Research Council Canada; National Aeronautics & Space Administration (NASA); NASA Jet Propulsion Laboratory (JPL); California Institute of Technology; American Museum of Natural History (AMNH); California Institute of Technology; Northwestern University; Northwestern University; University of California System; University of California San Diego; University of Hawaii System; Max Planck Society; Space Telescope Science Institute; University of California System; University of California Santa Cruz; Johns Hopkins University; Max Planck Society; Centre National de la Recherche Scientifique (CNRS); Universite Cote d'Azur; Observatoire de la Cote d'Azur; University of Cologne; Max Planck Society; Universidade do Porto; Universidade de Lisboa; University of Exeter; University of Southampton; Stockholm University; Communaute Universite Grenoble Alpes; Universite Grenoble Alpes (UGA); Centre National de la Recherche Scientifique (CNRS); Institut de Planetologie et d'Astrophysique de Grenoble (IPAG); University of Duisburg Essen; Eberhard Karls University of Tubingen; University of Bern; University of Cambridge; Academia Sinica - Taiwan; Leiden University - Excl LUMC; Leiden University; Aix-Marseille Universite; Centre National de la Recherche Scientifique (CNRS)
• 刊物名称: Nature
• ISSN/ISSBN: 0028-4008
• DOI: 10.1038/s41586-024-08064-x
• 发表日期: 2024-10-31
• 页码: 1070-+
• 关键词: infrared-spectrum; DISCOVERY; mass; multiplicity; companions; detections; stars

摘要

Owing to their similarities with giant exoplanets, brown dwarf companions of stars provide insights into the fundamental processes of planet formation and evolution. From their orbits, several brown dwarf companions are found to be more massive than theoretical predictions given their luminosities and the ages of their host stars(1-3). Either the theory is incomplete or these objects are not single entities. For example, they could be two brown dwarfs each with a lower mass and intrinsic luminosity(1,4). The most problematic example is Gliese229B (refs.(5,6)), which is at least 2-6 times less luminous than model predictions given its dynamical mass of 71.40.6 Jupiter masses (M-Jup) (ref.(1)). We observed Gliese229B with the GRAVITY interferometer and, separately, the CRIRES+ spectrograph at the Very Large Telescope. Both sets of observations independently resolve Gliese229B into two components, Gliese229Ba and Bb, settling the conflict between theory and observations. The two objects have a flux ratio of 0.47 +/- 0.03 at a wavelength of 2 mu m and masses of 38.1 +/- 1.0 and 34.4 +/- 1.5M(Jup), respectively. They orbit each other every 12.1days with a semimajor axis of 0.042 astronomical units (au). The discovery of Gliese229BaBb, each only a few times more massive than the most massive planets, and separated by 16 times the Earth-moon distance, raises new questions about the formation and prevalence of tight binary brown dwarfs around stars.