Tilling, I. and Woitke, P. and Meeus, G. and Mora, A. and Montesinos, B. and Riviere-Marichalar, P. and Eiroa, C. and Thi, W.-F. and Isella, A. and Roberge, A. and Martin-Zaidi, C. and Kamp, I. and Pinte, C. and Sandell, G. and Vacca, W. D. and Ménard, F. and Mendigutía, I. and Duchêne, G. and Dent, W. R. F. and Aresu, G. and Meijerink, R. and Spaans, M. (2012) Gas modelling in the disc of HD 163296. Astronomy and Astrophysics, 538 . Art. No. A20. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20120404-090545717
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We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of ~4 Myr, with evidence of a circumstellar disc extending out to ~540 AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (GAS in Protoplanetary Systems), consisting of a detection of the [Oi] 63 μm line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the ^(12)CO 3–2, 2–1 and ^(13)CO J = 1–0 line transitions, as well as an upper limit for the H_2 0–0 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9–100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry.
|Additional Information:||© 2012 ESO. Received 18 March 2011. Accepted 2 November 2011. Published online 27 January 2012.|
|Subject Keywords:||circumstellar matter; astrochemistry; stars: pre-main sequence; protoplanetary disks; stars: fundamental parameters; line: formation|
|Official Citation:||Gas modelling in the disc of HD 163296 A20 I. Tilling et al. Published online: 27 January 2012 DOI: http://dx.doi.org/10.1051/0004-6361/201116919|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||04 Apr 2012 16:42|
|Last Modified:||26 Dec 2012 15:01|
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