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Low-excitation atomic gas around evolved stars. II. ISO observations of O-rich nebulae

Castro-Carrizo, A. and Bujarrabal, V. and Fong, D. and Meixner, M. and Tielens, A. G. G. M. and Latter, W. B. and Barlow, M. J. (2001) Low-excitation atomic gas around evolved stars. II. ISO observations of O-rich nebulae. Astronomy and Astrophysics, 367 (2). pp. 674-693. ISSN 0004-6361. doi:10.1051/0004-6361:20000433.

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We have observed atomic fine-structure lines in the far-infrared (FIR) from 12 oxygen-rich evolved stars. The sample is composed of mostly proto-planetary nebulae (PPNe) and some planetary nebulae (PNe) and asymptotic giant branch (AGB) stars. ISO LWS and SWS observations of [O i], [C ii], [N ii], [Si i], [Si ii], [S i], [Fe i], and [Fe ii] lines were obtained. Taking into account also the sample presented by Fong et al. (Paper I) of carbon-rich evolved stars, we find that PPNe emit in these low-excitation atomic transitions only when the central star is hotter than ∼10 000 K. This result suggests that such lines predominantly arise from photodissociation regions (PDRs), and not from shocked regions. The line widths determined from our Fabry-Perot data also suggest that the FIR lines arise from relatively quiescent PDR gas, as opposed to shocked gas. Our results are in reasonable agreement with predictions from PDR emission models, allowing the estimation of the density of the emitting layers by comparison with the model results. On the other hand, the comparison with predictions of the emission from J-type and C-type shocked regions suggests that detected lines do not come from shocks. The [C ii] line flux has been used to measure the mass of the low-excitation atomic component in PPNe, since this transition has been found to be a useful model-independent probe to estimate the total mass of these PDRs. The derivation of the mass formula and assumptions made are also discussed.

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Additional Information:© 2001 ESO. Article published by EDP Sciences. Received 11 July 2000; Accepted 24 November 2000; Published online 15 February 2001. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the United Kingdom) and with the participation of ISAS and NASA. A. Castro-Carrizo and V. Bujarrabal have been partially supported by the CYCIT and the PNIE under grants PB96-104, 1FD97-1442 and ESP99-1291-E. D. Fong and M. Meixner have been supported by NASA JPL 961504 and NASA NAG 5-3350. M. Meixner has also been supported by NSF AST-97-33697. W. B. Latter and A. G. G. M. Tielens acknowledge additional support from NASA grant 399-20-61 from the Long Term Space Astrophysics Program. We are grateful to N. Trams, A. Heras and D. Kunze for their help in the analysis of the data. We also thank A. K. Speck for the enlightening discussions about properties of dust and J. Alcolea for his help during the first phases of the project. The ISO Spectral Analysis Package (ISAP) is a joint development by the LWS and SWS Instrument Teams and Data Centers. Contributing institutes are CESR, IAS, IPAC, MPE, RAL and SRON. OSIA is a joint development of the SWS consortium. Contributing institutes are SRON, MPE, KUL and the ESA Astrophysics Division.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Comisión Interministerial de Ciencia y Tecnología (CICYT)PB96-104
Comisión Interministerial de Ciencia y Tecnología (CICYT)1FD97-1442
Comisión Interministerial de Ciencia y Tecnología (CICYT)ESP99-1291-E
NASANAG 5-3350
Subject Keywords:atomic data - stars: AGB and post-AGB - (Stars:) circumstellar matter - stars: mass-loss - (ISM:) planetary nebulae
Issue or Number:2
Record Number:CaltechAUTHORS:20180213-161335427
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Official Citation:Low-excitation atomic gas around evolved stars - II. ISO observations of O-rich nebulae A. Castro-Carrizo, V. Bujarrabal, D. Fong, M. Meixner, A. G. G. M. Tielens, W. B. Latter and M. J. Barlow A&A, 367 2 (2001) 674-693. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84818
Deposited By: Tony Diaz
Deposited On:14 Feb 2018 00:27
Last Modified:15 Nov 2021 20:23

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