First Detection Of Near-Infrared Line Emission From Organics In Young Circumstellar Disks

dc.contributor.utaustinauthorSalyk, Coletteen_US
dc.creatorMandell, Avi M.en_US
dc.creatorBast, Jeanetteen_US
dc.creatorvan Dishoeck, Ewine F.en_US
dc.creatorBlake, Geoffrey A.en_US
dc.creatorSalyk, Coletteen_US
dc.creatorMumma, Michael J.en_US
dc.creatorVillanueva, Geronimoen_US
dc.description.abstractWe present an analysis of high-resolution spectroscopy of several bright T Tauri stars using the CRIRES spectrograph on the Very Large Telescope and NIRSPEC spectrograph on the Keck Telescope, revealing the first detections of emission from HCN and C2H2 in circumstellar disks at near-infrared wavelengths. Using advanced data reduction techniques, we achieve a dynamic range with respect to the disk continuum of similar to 500 at 3 mu m, revealing multiple emission features of H2O, OH, HCN, and C2H2. We also present stringent upper limits for two other molecules thought to be abundant in the inner disk, CH4 and NH3. Line profiles for the different detected molecules are broad but centrally peaked in most cases, even for disks with previously determined inclinations of greater than 20 degrees, suggesting that the emission has both a Keplerian and non-Keplerian component as observed previously for CO emission. We apply two different modeling strategies to constrain the molecular abundances and temperatures: we use a simplified single-temperature local thermal equilibrium (LTE) slab model with a Gaussian line profile to make line identifications and determine a best-fit temperature and initial abundance ratios, and we compare these values with constraints derived from a detailed disk radiative transfer model assuming LTE excitation but utilizing a realistic temperature and density structure. Abundance ratios from both sets of models are consistent with each other and consistent with expected values from theoretical chemical models, and analysis of the line shapes suggests that the molecular emission originates from within a narrow region in the inner disk (R < 1 AU).en_US
dc.description.sponsorshipGoddard Center for Astrobiologyen_US
dc.description.sponsorshipNetherlands Organization of Scientific Research (NWO) 614.000.605en_US
dc.description.sponsorshipNetherlands Research School for Astronomy (NOVA)en_US
dc.description.sponsorshipW. M. Keck Foundationen_US
dc.identifier.citationMandell, Avi M., Jeanette Bast, Ewine F. Van Dishoeck, Geoffrey A. Blake, Colette Salyk, Michael J. Mumma, and Geronimo Villanueva. "First detection of Near-infrared line emission from organics in young circumstellar disks." The Astrophysical Journal, Vol. 747, No. 2 (Mar., 2012): 92.en_US
dc.relation.ispartofserialAstrophysical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectline: profilesen_US
dc.subjectplanets and satellites: formationen_US
dc.subjectprotoplanetary disksen_US
dc.subjectstars: low-massen_US
dc.subjectt-tauri starsen_US
dc.subjectplanet-forming regionen_US
dc.subjectmidinfrared molecular-emissionen_US
dc.subjectspitzer spectroscopic surveyen_US
dc.subjectprotoplanetary disksen_US
dc.subjectstellar objectsen_US
dc.subjectmass starsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleFirst Detection Of Near-Infrared Line Emission From Organics In Young Circumstellar Disksen_US

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