Recent outburst activity of the symbiotic binary AG Draconis

TL;DR

This paper analyzes the recent outburst activity of the symbiotic binary AG Draconis, focusing on photometric, spectroscopic behavior, and white dwarf temperature variations during multiple outbursts from 2015 to 2017.

Contribution

It provides a detailed study of the recent outbursts of AG Dra, including analysis of emission line behavior and white dwarf temperature changes, improving understanding of outburst mechanisms.

Findings

Confirmed multiple recent outbursts in 2015, 2016, and 2017.

Identified the importance of disentangling effects in emission line variations.

Reported on orbital variations and absorption effects on emission lines.

Abstract

The symbiotic binary AG Dra regularly undergoes quiescent and active stages which consist of several outbursts repeating with about 360d interval. The recent outburst activity of AG Dra started by the minor outburst in the late spring of 2015 and was definitely confirmed by the outbursts in April 2016 and May 2017. In the presented work, the photometric and spectroscopic behaviour of the recent outburst activity of AG Dra is presented in detail. Moreover, the temperature of the white dwarf in AG Dra is studied based on the behaviour of the prominent emission lines. We show that a disentanglement of particular effects in the observed changes of the emission lines is crucial to investigate the intrinsic white dwarf temperature variations related to outburst activity of this strongly interacting binary. We also report the effects of the low excitation lines orbital variations and of the H$_{\beta}$ absorption component on their equivalent widths as well as consequences of the approximations used in our previous works.