The spectra of evolved stars at 20–25 GHz: Tracing circumstellar chemistry during the asymptotic giant branch to planetary nebula transition

2020/04/06 by Yong Zhang, Wayne Chau, W. Y. Chau +3
Chemistry · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Asymptotic giant branch #Molecular Spectroscopy and Structure #Nebula #Physics #Planetary nebula #Protoplanetary nebula #Spectral line #Stars #Stellar evolution #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR

paper · pdf · doi:10.1093/pasj/psaa032

37 pages. 8 figures, Accepted for publication in PASJ

openalex publication_date 2020/04/06 · arxiv created 2020/06/12 · arxiv updated 2020/06/17 · openalex created_date 2020/06/19 · openalex updated_date 2026/08/05

Abstract

Abstract We report an unbiased radio line survey towards the circumstellar envelopes of evolved stars at the frequency range from 20 to 25 GHz, aiming to obtain a more complete unbiased picture of the chemical evolution in the final stages of stellar evolution. The observation sample includes the asymptotic giant branch (AGB) star IRC +10216, the proto-planetary nebulae (PPNs) CRL 2688 and CRL 618, and the young planetary nebula (PN) NGC 7027, representing an evolutionary sequence spanning about 10000 years. Rotational transitions from cyanopolyyne chains and inversion lines from ammonia are detected in the AGB star and PPNs, while the PN displays several recombination lines. The different spectral behaviors of these evolved stars clearly reflect the evolution of circumstellar chemistry during the AGB–PPN–PN transitions.

Citations

• A Spectral Line Survey of NGC 7027 at Millimeter Wavelengths
• A Spectral Line Survey in the 2 and 1.3 mm Windows toward the Carbon‐rich Envelope of IRC +10216
• The Slowly Expanding Envelope of CRL 618 Probed with HC3N Rotational Ladders
• A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz