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Title: A MOLECULAR LINE SURVEY OF THE CARBON-RICH PROTOPLANETARY NEBULA AFGL 2688 IN THE 3 mm AND 1.3 mm WINDOWS

We present a spectral line survey of the protoplanetary nebula (PPN) AFGL 2688 in the frequency ranges of 71-111 GHz, 157-160 GHz, and 218-267 GHz using the Arizona Radio Observatory 12 m telescope and the Heinrich Hertz Submillimeter Telescope. A total of 143 individual spectral features associated with 32 different molecular species and isotopologues were identified. The molecules C{sub 3}H, CH{sub 3}CN, H{sub 2}CO, H{sub 2}CS, and HCO{sup +} were detected for the first time in this object. By comparing the integrated line strengths of different transitions, we are able to determine the rotation temperatures, column densities, and fractional abundances of the detected molecules. The C, O, and N isotopic ratios in AFGL 2688 are compared with those in IRC+10216 and the Sun, and were found to be consistent with stellar nucleosynthesis theory. Through comparisons of molecular line strengths in asymptotic giant branch stars, PPNs, and planetary nebulae, we discuss the evolution in circumstellar chemistry in the late stages of evolution.
Authors:
; ; ;  [1] ;  [2]
  1. Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (Hong Kong)
  2. Institute of Physics, Vietnam Academy of Science and Technology, 10 DaoTan Street, BaDinh, Hanoi (Viet Nam)
Publication Date:
OSTI Identifier:
22131046
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACETONITRILE; CARBON; FORMALDEHYDE; GHZ RANGE; GIANT STARS; ISOTOPE RATIO; METHANOL; MOLECULES; NITROGEN; NUCLEOSYNTHESIS; OXYGEN; PLANETARY NEBULAE; PROTOPLANETS; ROTATION; SUN; TELESCOPES