2001/03/02 by Hee-Won Lee, Yong-Woo Kang, Yong-Ik Byun · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/319830
8 pages, 2 figures, accepted for publication in the Astrophysical Journal Letters
arxiv created 2001/03/02 · openalex publication_date 2001/04/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
In this Letter, we report the detection of an emission feature at around 6545 Å in the spectra of the bipolar planetary nebula M2-9 and the symbiotic stars RR Telescopii and He 2-106 and propose to identify it as the He II Raman-scattered feature. This feature was predicted by Nussbaumer, Schmid, & Vogel, who suggested that it was formed through Raman scattering by atomic hydrogen of He II n = 6 → n = 2 photons with a slightly shorter wavelength than that of Lyβ. The scattering cross section, ~10 -20 cm 2 for this process, implies the existence of a neutral hydrogen component with a column density N ~ 10 20 cm -2 around the He II emission regions in these objects, which are believed to be associated with the mass-loss process in the late stage of stellar evolution. Brief discussions on the astrophysical implications of Raman scattering in these objects are presented.