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Gas lines from the 5-Myr old optically thin disk around HD141569A - Herschel observations and modeling

Thi, W.-F. and Pinte, C. and Pantin, E. and Augereau, J. C. and Meeus, G. and Ménard, F. and Martin-Zaїdi, C. and Woitke, P. and Riviere-Marichalar, P. and Kamp, I. and Carmona, A. and Sandell, G. and Eiroa, C. and Dent, W. and Montesinos, B. and Aresu, G. and Meijerink, R. and Spaans, M. and White, G. and Ardila, D. and Lebreton, J. and Mendigutía, I. and Brittain, S. (2014) Gas lines from the 5-Myr old optically thin disk around HD141569A - Herschel observations and modeling. Astronomy and Astrophysics, 561 . Art. No. A50. ISSN 0004-6361. http://resolver.caltech.edu/CaltechAUTHORS:20140306-153112065

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Abstract

Context. The gas- and dust dissipation processes in disks around young stars remain uncertain despite numerous studies. At the distance of ~99–116 pc, HD 141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disk, probably in transition between a massive primordial disk and a debris disk. Atomic and molecular gases have been found in the structured 5-Myr old HD 141569A disk, making HD 141569A the perfect object within which to directly study the gaseous atomic and molecular component. Aims. We wish to constrain the gas and dust mass in the disk around HD 141569A. Methods. We observed the fine-structure lines of O I at 63 and 145 μm and the C ii line at 157 μm with the PACS instrument onboard the Herschel Space Telescope as part of the open-time large program GASPS. We complemented the atomic line observations with archival Spitzer spectroscopic and photometric continuum data, a ground-based VLT-VISIR image at 8.6 μm, and ^(12)CO fundamental ro-vibrational and pure rotational J = 3–2 observations. We simultaneously modeled the continuum emission and the line fluxes with the Monte Carlo radiative transfer code MCFOST and the thermo-chemical code ProDiMo to derive the disk gas- and dust properties assuming no dust settling. Results. The models suggest that the oxygen lines are emitted from the inner disk around HD 141569A, whereas the [C ii] line emission is more extended. The CO submillimeter flux is emitted mostly by the outer disk. Simultaneous modeling of the photometric and line data using a realistic disk structure suggests a dust mass derived from grains with a radius smaller than 1 mm of ~2.1 × 10^(-7)M_⊙ and from grains with a radius of up to 1 cm of 4.9 × 10^(-6)M_⊙. We constrained the polycyclic aromatic hydrocarbons (PAH) mass to be between 2 × 10^(-11) and 1.4 × 10^(-10)M_⊙ assuming circumcircumcoronene (C_(150)H_(30)) as the representative PAH. The associated PAH abundance relative to hydrogen is lower than those found in the interstellar medium (3 × 10^(-7)) by two to three orders of magnitude. The disk around HD 141569A is less massive in gas (2.5 to 4.9 × 10^(-4)M_⊙ or 67 to 164 M_⊕) and has a flat opening angle (<10%). Conclusions. We constrained simultaneously the silicate dust grain, PAH, and gas mass in a ~5-Myr old Herbig Ae disk. The disk-averaged gas-to-dust-mass is most likely around 100, which is the assumed value at the disk formation despite the uncertainties due to disagreements between the different gas tracers. If the disk was originally massive, the gas and the dust would have dissipated at the same rate.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://www.aanda.org/articles/aa/abs/2014/01/aa22150-13/aa22150-13.htmlPublisherArticle
http://dx.doi.org/10.1051/0004-6361/201322150DOIArticle
http://arxiv.org/abs/1309.5098arXivDiscussion Paper
Additional Information:© 2014 ESO. Received 26 June 2013. Accepted 10 September 2013. Published online 23 December 2013. We thank ANR (contracts ANR-07-BLAN-0221 and ANR- 2010-JCJC-0504-01) and PNPS of CNRS/INSU, France for support. W.F.T., I.K., and P.W. acknowledge funding from the EU FP7-2011 under Grant Agreement No. 284405 (PERG06-GA-2009-256513). F.M. acknowledges support from the Millenium Science Initiative (Chilean Ministry of Economy), through grant “Nucleus P10-022-F”. Computations presented in this paper were performed at the Service Commun de Calcul Intensif de l’Observatoire de Grenoble (SCCI) on the super-computer Fostino funded by Agence Nationale pour la Recherche under contracts ANR-07-BLAN-0221, ANR-2010-JCJC- 0504-01 and ANR-2010-JCJC-0501-01. C. Eiroa, G. Meeus, and B. Montesinos are partly supported by Spanish grant AYA 2011-26202. We thank the referee for the useful comments.
Funders:
Funding AgencyGrant Number
Agence Nationale de la Recherche (ANR) ANR-07-BLAN-0221
Agence Nationale de la Recherche (ANR) ANR-2010-JCJC-0504-01
PNPSUNSPECIFIED
CNRS/INSU (France)UNSPECIFIED
European Union FP7-2011284405
European Commission 7th Framework ProgramPERG06-GA-2009-256513
Chilean Ministry of Economy Millennium Science InitiativeNucleus P10-022-F
Agence Nationale de la Recherche (ANR) ANR-07-BLAN-0221
Agence Nationale de la Recherche (ANR) ANR-2010-JCJC-0504-01
Agence Nationale de la Recherche (ANR) ANR-2010-JCJC-0501-01
Spanish grantAYA 2011-26202
Subject Keywords:stars: pre-main sequence, astrochemistry, protoplanetary disks
Record Number:CaltechAUTHORS:20140306-153112065
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140306-153112065
Official Citation:Gas lines from the 5-Myr old optically thin disk around HD 141569A - Herschel observations and modeling W.-F. Thi, C. Pinte, E. Pantin, J. C. Augereau, G. Meeus, F. Ménard, C. Martin-Zaïdi, P. Woitke, P. Riviere-Marichalar, I. Kamp, A. Carmona, G. Sandell, C. Eiroa, W. Dent, B. Montesinos, G. Aresu, R. Meijerink, M. Spaans, G. White, D. Ardila, J. Lebreton, I. Mendigutía and S. Brittain A&A 561 A50 (2014) DOI: http://dx.doi.org/10.1051/0004-6361/201322150
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44187
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:07 Mar 2014 15:24
Last Modified:07 Mar 2014 15:24

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