Aperture synthesis observations of molecules in CRL 2688

Nguyen-Q-Rieu, John H Bieging

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We have used the BIMA-Hat Creek interferometer to map the line emission of H13CN, HC3N, HNC, and SiS at 3 mm toward the bipolar object CRL 2688 (the " Egg nebula "). The molecular emission distributions show a slight departure from spherical geometry and have a major axis (∼10″) almost aligned with the direction of the dust lane of the Egg nebula. The SiS emission is less extended than that of the organic molecules and is confined to the central region of the envelope. A pedestal emission at both redshifted (∼ -15 to ∼ -5 km s-1) and blueshifted (∼ -65 to ∼ -45 km s-1) wings detected in the H13CN, and HC3N spectra may arise from a bipolar outflow or a time-variable wind corresponding to a high-speed wind phase. The abundances of H13CN, HC3N, and HNC in CRL 2688 are comparable to those observed in IRC + 10216. SiS is depleted in CRL 2688 by an order of magnitude with respect to the average SiS abundance observed in IRC +10216. It is shown that the determination of the abundances of HCN and H13CN is strongly affected by the self-absorption of the optically thick blended hyperfine components in the expanding envelope. If self-absorption is ignored, the HCN and H13CN abundances could be underestimated by a factor of ∼3.

Original languageEnglish (US)
Pages (from-to)131-137
Number of pages7
JournalAstrophysical Journal
Volume359
Issue number1
StatePublished - Aug 10 1990
Externally publishedYes

Fingerprint

apertures
self absorption
eggs
synthesis
nebulae
molecules
envelopes
egg
interferometer
wings
outflow
interferometers
dust
wind velocity
high speed
geometry

Keywords

  • Interstellar: molecules
  • Nebulae: abundances
  • Nebulae: individual (CRL 2688)
  • Nebulae: structure

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Aperture synthesis observations of molecules in CRL 2688. / Nguyen-Q-Rieu, ; Bieging, John H.

In: Astrophysical Journal, Vol. 359, No. 1, 10.08.1990, p. 131-137.

Research output: Contribution to journalArticle

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N2 - We have used the BIMA-Hat Creek interferometer to map the line emission of H13CN, HC3N, HNC, and SiS at 3 mm toward the bipolar object CRL 2688 (the " Egg nebula "). The molecular emission distributions show a slight departure from spherical geometry and have a major axis (∼10″) almost aligned with the direction of the dust lane of the Egg nebula. The SiS emission is less extended than that of the organic molecules and is confined to the central region of the envelope. A pedestal emission at both redshifted (∼ -15 to ∼ -5 km s-1) and blueshifted (∼ -65 to ∼ -45 km s-1) wings detected in the H13CN, and HC3N spectra may arise from a bipolar outflow or a time-variable wind corresponding to a high-speed wind phase. The abundances of H13CN, HC3N, and HNC in CRL 2688 are comparable to those observed in IRC + 10216. SiS is depleted in CRL 2688 by an order of magnitude with respect to the average SiS abundance observed in IRC +10216. It is shown that the determination of the abundances of HCN and H13CN is strongly affected by the self-absorption of the optically thick blended hyperfine components in the expanding envelope. If self-absorption is ignored, the HCN and H13CN abundances could be underestimated by a factor of ∼3.

AB - We have used the BIMA-Hat Creek interferometer to map the line emission of H13CN, HC3N, HNC, and SiS at 3 mm toward the bipolar object CRL 2688 (the " Egg nebula "). The molecular emission distributions show a slight departure from spherical geometry and have a major axis (∼10″) almost aligned with the direction of the dust lane of the Egg nebula. The SiS emission is less extended than that of the organic molecules and is confined to the central region of the envelope. A pedestal emission at both redshifted (∼ -15 to ∼ -5 km s-1) and blueshifted (∼ -65 to ∼ -45 km s-1) wings detected in the H13CN, and HC3N spectra may arise from a bipolar outflow or a time-variable wind corresponding to a high-speed wind phase. The abundances of H13CN, HC3N, and HNC in CRL 2688 are comparable to those observed in IRC + 10216. SiS is depleted in CRL 2688 by an order of magnitude with respect to the average SiS abundance observed in IRC +10216. It is shown that the determination of the abundances of HCN and H13CN is strongly affected by the self-absorption of the optically thick blended hyperfine components in the expanding envelope. If self-absorption is ignored, the HCN and H13CN abundances could be underestimated by a factor of ∼3.

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