The optical spectrum of R Coronae Borealis close to 2003 decline

TL;DR

This paper presents high-resolution spectral observations of R Coronae Borealis during its 2003 decline, detailing emission and absorption features, radial velocities, and molecular bands in different decline phases.

Contribution

It provides detailed spectral analysis of R CrB during a decline, including measurements of emission and absorption lines and molecular bands, enhancing understanding of its atmospheric changes.

Findings

C_2 Swan band in emission during decline

Absorption lines of CN and FeI observed

Radial velocities of spectral features measured

Abstract

Two sets of high-resolution spectra of R CrB obtained during the 2003 light decline are described. The first set was obtained on the descending branch of the light curve when V ~12.0 and the second one in the recovery phase with V ~7.5. The usual sharp and broad emissions are described and the lines radial velocities measured. C_2 Swan system (0,0) band was found to be in emission for the first set. The other C_2 bands were in absorption. Few CN red system (5,1) band rotational lines and low excitation FeI lines were in absorption. A table with measured radial velocities of various spectral features is presented.