title: Possible planet formation in the young, low-mass, multiple stellar system GG Tau A.
abstract: The formation of planets around binary stars may be more difficult than around single stars. In a close binary star (with a separation of less than a hundred astronomical units), theory predicts the presence of circumstellar disks around each star, and an outer circumbinary disk surrounding a gravitationally cleared inner cavity around the stars. Given that the inner disks are depleted by accretion onto the stars on timescales of a few thousand years, any replenishing material must be transferred from the outer reservoir to fuel planet formation (which occurs on timescales of about one million years). Gas flowing through disk cavities has been detected in single star systems. A circumbinary disk was discovered around the young low-mass binary system GG Tau A (ref. 7), which has recently been shown to be a hierarchical triple system. It has one large inner disk around the single star, GG Tau Aa, and shows small amounts of shocked hydrogen gas residing within the central cavity, but other than a single weak detection, the distribution of cold gas in this cavity or in any other binary or multiple star system has not hitherto been determined. Here we report imaging of gas fragments emitting radiation characteristic of carbon monoxide within the GG Tau A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disk (around GG Tau Aa) beyond the accretion lifetime, leaving time for planet formation to occur there. These results show the complexity of planet formation around multiple stars and confirm the general picture predicted by numerical simulations.
authors.affiliation: 1] Université de Bordeaux, LAB, UMR 5804, F-33270 Floirac, France [2] Centre National de la Recherche Scientifique (CNRS), LAB, UMR 5804, F-33270 Floirac, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Dutrey
authors.affiliation: 1] Université de Bordeaux, LAB, UMR 5804, F-33270 Floirac, France [2] Centre National de la Recherche Scientifique (CNRS), LAB, UMR 5804, F-33270 Floirac, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Di Folco
authors.affiliation: 1] Université de Bordeaux, LAB, UMR 5804, F-33270 Floirac, France [2] Centre National de la Recherche Scientifique (CNRS), LAB, UMR 5804, F-33270 Floirac, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Guilloteau
authors.affiliation: Centro de Radioastronomia y Astrofisica (CRyA), University of Mexico, Apartado Postal 3-72, 58089 Morelia, Michoacan, Mexico.
authors.forename: Yann
authors.initials: Y
authors.lastname: Boehler
authors.affiliation: Department of Physics and Astronomy, Colgate University, 13 Oak Drive, Hamilton, New York 13346, USA.
authors.forename: Jeff
authors.initials: J
authors.lastname: Bary
authors.affiliation: Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, USA.
authors.forename: Tracy
authors.initials: T
authors.lastname: Beck
authors.affiliation: Institut de Planetologie et d'Astrophysique de Grenoble (IPAG), UMR 5274, BP 53, F-38041 Grenoble Cedex 9, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Beust
authors.affiliation: 1] Université de Bordeaux, LAB, UMR 5804, F-33270 Floirac, France [2] Institut de RadioAstronomie Millimetrique (IRAM), 300 rue de la Piscine, F-38046 Saint Martin d'Hères, France.
authors.forename: Edwige
authors.initials: E
authors.lastname: Chapillon
authors.affiliation: Institut de RadioAstronomie Millimetrique (IRAM), 300 rue de la Piscine, F-38046 Saint Martin d'Hères, France.
authors.forename: Fredéric
authors.initials: F
authors.lastname: Gueth
authors.affiliation: 1] Université de Bordeaux, LAB, UMR 5804, F-33270 Floirac, France [2] Centre National de la Recherche Scientifique (CNRS), LAB, UMR 5804, F-33270 Floirac, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Huré
authors.affiliation: 1] Université de Bordeaux, LAB, UMR 5804, F-33270 Floirac, France [2] Centre National de la Recherche Scientifique (CNRS), LAB, UMR 5804, F-33270 Floirac, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Pierens
authors.affiliation: Institut de RadioAstronomie Millimetrique (IRAM), 300 rue de la Piscine, F-38046 Saint Martin d'Hères, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Piétu
authors.affiliation: Stony Brook University, Stony Brook, New York 11794-3800, USA.
authors.forename: Michal
authors.initials: M
authors.lastname: Simon
authors.affiliation: Academia Sinica Institute of Astronomy and Astrophysics, PO Box 23-141, Taipei 106, Taiwan.
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Tang