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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 693564.0, MPI für Astronomie / Publikationen_mpia
ALMA continuum observations of a 30 Myr old gaseous debris disk around HD 21997
Authors:Moór, A.; Juhász, A.; Kóspál, Á.; Ábrahám, P.; Apai, D.; Csengeri, T.; Grady, C.; Henning, Th.; Hughes, A. M.; Kiss, Cs.; Pascucci, I.; Schmalzl, M.; Gabányi, K.
Date of Publication (YYYY-MM-DD):2013
Title of Journal:The Astrophysical Journal Letters
Issue / Number:2
Start Page:id. L25 (6 pp)
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Circumstellar disks around stars older than 10 Myr are expected to be gas-poor. There are, however, two examples of old (30-40 Myr) debris-like disks containing a detectable amount of cold CO gas. Here we present Atacama Large Millimeter/Submillimeter Array (ALMA) and Herschel Space Observatory observations of one of these disks, around HD 21997, and study the distribution and origin of the dust and its connection to the gas. Our ALMA continuum images at 886 μm clearly resolve a broad ring of emission within a diameter of ~4.''5, adding HD 21997 to the dozen debris disks resolved at (sub)millimeter wavelengths. Modeling the morphology of the ALMA image with a radiative transfer code suggests inner and outer radii of ~55 and ~150 AU, and a dust mass of 0.09 M . Our data and modeling hints at an extended cold outskirt of the ring. Comparison with the morphology of the CO gas in the disk reveals an inner dust-free hole where gas nevertheless can be detected. Based on dust grain lifetimes, we propose that the dust content of this gaseous disk is of secondary origin and is produced by planetesimals. Since the gas component is probably primordial, HD 21997 is one of the first known examples of a hybrid circumstellar disk, a thus-far little studied late phase of circumstellar disk evolution.
Free Keywords:circumstellar matter; infrared: stars; stars: individual: HD 21997
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X [ID No:1]
URL:http://cdsads.u-strasbg.fr/abs/2013ApJ...777L..25M [ID No:2]
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