AG Draconis, Shelyak Spectros in the spotlight !

By Olivier Garde

AG Draconis is one of the most fascinating stars to observe, particularly through spectroscopy. This binary system consists of a red giant star and a white dwarf star. Every ten to fifteen years, it undergoes a major outburst of luminosity. The direct cause of these outbursts are thermonuclear explosions on the surface of the white dwarf that is accreting hydrogen from its binary companion until a critical mass and temperature are reached where the thermonuclear reactions can start.

During these outbursts, the matter surrounding the binary system is strongly ionised by the white dwarf radiations. As a result, strong emission lines are visible in spectra that can be used to infer the surface temperature of the white dwarf, a pivotal factor in understanding the mechanisms at work in this type of binary system.

An article on the last outburst of the symbiotic star AG Draconis  (magnitude V ± 9.7) was published in the magazine Proceedings of Science by 3 astrophysicists who used amateur spectral data from the ARAS base.

The peculiarity of this article comes from the fact that among the 7 amateurs who realized the hundred spectrum object of this publication, 5 used a Shelyak spectrograph: 3 eShels, 1 Lhires III and 1 Lisa The measurement campaign spans more than 900 days and the authors wanted to thank the amateurs who took part in this measurement campaign.

For Shelyak Instruments management, this publication, after many others, validates the philosophy used from the start as a guideline for the company’s developpment : offering high-performance although affordable products that allow amateurs astronomers and professional astrophysicists to work hand-in-hand in the understanding of our universe.

Interesting fact : situated in the circumpolar constellation of Draco, AG Draconis is permanently observable in the Northern hemisphere.

Ladies and Gentlemen, start your spectros !