The slowly expanding envelope of CRL618 probed with HC3N rotational ladders

Abstract

Lines from HC3N and isotopic substituted species in ground and vibrationally excited states produce crowded millimeter and submillimeter wave spectra in the C-rich protoplanetary nebula CRL618. The complete sequence of HC3N rotational lines from J=9-8 to J=30-29 has been observed with the IRAM 30m telescope toward this object. Lines from a total of 15 different vibrational states (including the fundamental), with energies up to 1100 cm^-1, have been detected for the main HC3N isotopomer. In addition, the CSO telescope has been used to complement this study in the range J=31-30 to J=39-38, with detections in five of these states, all of them below 700 cm^-1. Vibrationally excited HC3N rotational lines exhibit P-Cygni profiles at 3 mm, evolving to pure emission lineshapes at shorter wavelengths. This evolution of the line profile shows little dependence on the vibrational state from which they rotational lines arise. The absorption features are formed against the continuum emission, which has been successfully characterized in this work due to the large frequency coverage. The HC3N column density in front of the the continuum source has been determined by comparing the output of an array of models to the data. The best fits are obtained for column densities in the range 2.0-3.5 10$^17 cm^-2, consistent with previous estimates from ISO data, and TK in the range 250 to 275 K, in very good agreement with estimates made from the same ISO data.

arXiv comment24 pages, 7 figures, accepted in ApJ part I (Jul. 8, 2004)

References in corpus (5)

• Detection of HC11N in the Cold Dust Cloud TMC-1
• Chemical Evolution of the Circumstellar Envelopes of Carbon-rich Post-AGB objects
• Physical conditions in the Protoplanetary Nebula CRL 618 derived from observations of vibrationally excited HCCCN
• Detection of HCN Direct l-Type Transitions Probing Hot Molecular Gas in the Proto-Planetary Nebula CRL 618
• Multiple Molecular H2 Outflows in AFGL 618

Cited by in corpus (18)

• Rotational Excitation of HC_3N by H_2 and He at low temperatures
• Jets and Tori in Proto-Planetary Nebulae
• Molecular survey of CRL618
• Vibrationally excited HC3N in NGC 4418
• A spectral line survey of NGC 7027 at millimeter wavelengths
• New N-bearing species towards OH231.8+4.2: HNCO, HNCS, HC${}_3$N and NO
• Observational evidence of the formation of cyanopolyynes in CRL618 through the polimerization of HCN
• Herschel-SPIRE FTS spectroscopy of the carbon-rich objects AFGL 2688, AFGL 618 and NGC 7027
• Herschel/HIFI observations of molecular emission in protoplanetary nebulae and young planetary nebulae
• Rotational and high-resolution infrared spectrum of HC${}_3$N: global ro-vibrational analysis and improved line catalogue for astrophysical observations
• Herschel/HIFI observations of high-J CO transitions in the protoplanetary nebula CRL618
• Submillimeter Array Observation of the Proto-Planetary Nebula CRL 618 in the CO J=6-5 Line
• The abundances of polyacetylenes towards CRL618
• Mapping the Central Region of the PPN CRL 618 at Sub-arcsecond Resolution at 350 GHz
• A search for CO+ in planetary nebulae
• The molecular envelope of CRL 618: A new model based on Herschel/HIFI observations
• The spectra of evolved stars at 20--25\,GHz: tracing circumstellar chemistry during the asymptotic giant branch to planetary nebula transition
• Detection of 4765 MHz OH Emission in a Pre-Planetary Nebula -- CRL 618