The changing nebula around the hot R Coronae Borealis star DY Centauri

Abstract

Among the distinguishing characteristics of the remarkable hot R Coronae Borealis star DY Cen, which was recently found to be a spectroscopic binary, is the presence of nebular forbidden lines in its optical spectrum. A compilation of photometry from 1970 to the present suggests that the star has evolved to higher effective temperatures. Comparison of spectra from 2010 with earlier spectra show that between 2003 and 2010, the 6717 and 6730 A emission lines of [S II] underwent a dramatic change in their fluxes suggesting an increase in the nebula's electron density of 290 cm-3 to 3140 cm-3 from 1989 to 2010 while the stellar temperature increased from 19500 K to 25000 K. The nebular radius is about 0.02 pc, 60000 times bigger than the semimajor axis of DY Cen binary system. Rapid changes of stellar temperature and its response by the nebula demonstrate stellar evolution in action.

Accepted for publication in MNRAS (9 pages, 6 figures and 3 tables)

References in corpus (3)

• Stellar archaeology: the evolving spectrum of FG Sge
• High-resolution optical spectroscopy of DY Cen: diffuse interstellar bands in a proto-fullerene circumstellar environment?
• The hot R Coronae Borealis star DY Centauri is a binary

Cited by in corpus (5)

• PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results
• On helium-dominated stellar evolution: the mysterious role of the O(He)-type stars
• All Known Hot RCB Stars Are Fading Fast Over the Last Century
• SALT revisits DY Cen: a rapidly-evolving strontium-rich single helium star
• On the binary helium star DY Centauri: Chemical composition and evolutionary state