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Observations of Herbig Ae/Be Stars with Herschel/PACS: The Atomic and Molecular Contents of Their Protoplanetary DiscsWe observed a sample of 20 representative Herbig Ae/Be stars and 5 A-type debris discs with PACS onboard Herschel, as part of the GAS in Protoplanetary Systems (GASPS) project. The observations were done in spectroscopic mode, and cover the far-infrared lines of [OI], [CII], CO, CH+, H20, and OH. We have a [OI]63 micro/ detection rate of 100% for the Herbig Ae/Be and 0% for the debris discs. The [OI] 145 micron line is only detected in 25% and CO J = 18-17 in 45% (and fewer cases for higher J transitions) of the Herbig Ae/Be stars, while for [CII] 157 micron, we often find spatially variable background contamination. We show the first detection of water in a Herbig Ae disc, HD 163296, which has a settled disc. Hydroxyl is detected as well in this disc. First seen in HD 100546, CH+ emission is now detected for the second time in a Herbig Ae star, HD 97048. We report fluxes for each line and use the observations as line diagnostics of the gas properties. Furthermore, we look for correlations between the strength of the emission lines and either the stellar or disc parameters, such as stellar luminosity, ultraviolet and X-ray flux. accretion rate, polycyclic aromatic hydrocarbon (PAH) band strength, and flaring. We find that the stellar ultraviolet flux is the dominant excitation mechanism of [OI] 63 micron, with the highest line fluxes being found in objects with a large amount of flaring and among the largest PAH strengths. Neither the amount of accretion nor the X-ray luminosity has an influence on the line strength. We find correlations between the line flux of [OI]63 micron and [OI] 145 micron, CO J = IS-17 and [OI] 6300 A, and between the continuum flux at 63 micron and at 1.3 mm, while we find weak correlations between the line flux. of [OI] 63 micron and the PAH luminosity, the line flux of CO J = 3-2, the continuum flux at 63 pm, the stellar effective temperature, and the Br-gamma luminosity. Finally, we use a combination of the [OI] 63 micron and C(12)O J = 2-1 line fluxes to obtain order of magnitude estimates of the disc gas masses, in agreement with the values that we find from detailed modelling of two Herbig Ae/Be stars, HD 163296 and HD 169142.
Document ID
20120016037
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Meeus, G.
(Universidad Autonoma de Madrid Cantoblanco, Spain)
Montesinos, B.
(Instituto Nacional de Tecnica Aeroespacial Madrid, Spain)
Mendigutia, I.
(Universidad Autonoma de Madrid Cantoblanco, Spain)
Kamp, I.
(Kapteyn Astronomical Lab. Groningen, Netherlands)
Thi, W. F.
(Centre National de la Recherche Scientifique Grenoble, France)
Eiroa, C.
(Universidad Autonoma de Madrid Cantoblanco, Spain)
Grady, C. A.
(Eureka Scientific, Inc. Laurel, MD, United States)
Mathews, G.
(Hawaii Univ. Honolulu, HI, United States)
Sandell, G.
(Universities Space Research Association Moffett Field, CA, United States)
Martin-Zaidi, C.
(Centre National de la Recherche Scientifique Grenoble, France)
Brittain, S.
(Clemson Univ. SC, United States)
Dent, W. R. F.
(Atacama Large Millimeter Submillimeter Array Santiago, Chile)
Howard, C.
(Universities Space Research Association Moffett Field, CA, United States)
Menard, F.
(Centre National de la Recherche Scientifique Grenoble, France)
Pinte, C.
(Centre National de la Recherche Scientifique Grenoble, France)
Roberge, A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Vandenbussche, B.
(Katholieke Univ. te Leuven Belgium)
Williams, J. P.
(Hawaii Univ. Honolulu, HI, United States)
Date Acquired
August 26, 2013
Publication Date
June 14, 2012
Publication Information
Publication: Astronomy and Astrophysics
Publisher: EDP Sciences
Volume: 544
Subject Category
Astronomy
Report/Patent Number
GSFC.JA.7258.2012
Funding Number(s)
CONTRACT_GRANT: ANR-2010-JCJC-0504-01
CONTRACT_GRANT: PERG06-GA-2009-256513
CONTRACT_GRANT: EU 284405
Distribution Limits
Public
Copyright
Other

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