An episodically variable stellar wind in the planetary nebula IC\,4997
Luis F. Miranda, Jos\'e M. Torrelles, Jorge Lillo-Box

TL;DR
This study reveals episodic variability in the stellar wind of planetary nebula IC 4997 through high-resolution spectral analysis over decades, showing changes in emission profiles and linking wind activity to nebular line variations.
Contribution
It provides the first detailed temporal analysis of IC 4997's spectral line profile changes and links stellar wind variability to episodic nebular emission fluctuations.
Findings
Hα P Cygni profile changed to single-peaked, indicating wind weakening
Broad Hα wings narrowed, suggesting decreased Raman scattering efficiency
High-velocity [N II] component disappeared, likely due to lower electron density
Abstract
IC\,4997 is a planetary nebula well known by its variability. We present high-resolution spectra of IC\,4997 obtained in 1993, 2019, and 2020 that reveal changes in the H and [N\,{\sc ii}] emission line profiles, which had never been reported for this object. The H P\,Cygni emission profile observed in 1993 changed to a single-peaked profile in 2019--2020, implying that the stellar wind has largely weakened. The very broad H emission wings narrowed by a factor of 2 between 1993 and 2019--2020, indicating that the efficiency of the Rayleigh--Raman scattering has noticeably decreased. A high-velocity [N\,{\sc ii}] nebular component detected in 1993 is missing in 2019 and 2020, probably due to a decrease in its electron density. A correlation exists between the strength of the stellar wind and the episodic (50--60\,yr) variation in the [O\,{\sc…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
Taxonomy
TopicsStellar, planetary, and galactic studies · Astro and Planetary Science · Astrophysics and Star Formation Studies
