A Study of the Time Variability and Line Profile Variations of kappa Dra

TL;DR

This paper provides a detailed spectroscopic analysis of the Be star kappa Dra, revealing phase-locked radial velocity and line profile variations, and refining its orbital parameters using multiple measurement techniques.

Contribution

It introduces improved orbital elements for kappa Dra and analyzes phase-locked line profile variations using combined spectroscopic methods.

Findings

Radial velocity variations are phase-locked with the orbital period.

V/R variations are phase-locked with orbital motion.

Detected moving absorption bump in emission lines.

Abstract

In this study, we present a spectroscopic analysis of the bright Be star kappa Dra. Two independent sets of radial velocity velocities (RV) measurements were obtained by direct measurement and using a line profile disentangling technique. Using a combination of the solutions found by the codes FOTEL and KOREL, we revisited the binary nature of kappa Dra and derived improved orbital elements. From the RVs of the Balmer lines and also from some strong metallic lines we found that all RVs variations are phase-locked with the orbital period. V/R variations were obtained for H_alpha, H_beta, H_gamma and some other photospheric lines and they are found to be phase-locked with the orbital motion. A moving absorption bump superimposed over the H_alpha and H_beta emission line profiles was detected. The orbital solutions for kappa Dra were derived assuming a circular orbit with a period 61.5549 day and K = 6.81 km/s . The question of the line profile variability was discussed. We attempted to search for absorption or emission lines of the unresolved secondary component, we failed to find them.