Colloquia

Vitaly Neustroev-Spectral energy distribution of short-period Cataclysmic Variables: a search for period-bouncers

Colloquia

“Spectral energy distribution of short-period Cataclysmic Variables:
a search for period-bouncers”

Vitaly Neustroev

University of Oulu (Finland)

ABSTRACT

According to standard evolutionary theory, cataclysmic variables (CV) evolve from longer to shorter orbital periods until a minimum period P_min is reached. The period bouncers are such CVs that have passed beyond P_min and are evolving back toward longer periods, with the donor star now extremely dim. This has long been predicted to be the “graveyard” and current state of more than 40% of all CVs, though only about a dozen of more or less robust candidates for such period bouncer systems have been identified until now, out of a few thousand of known CVs. We recently took a novel approach based on multicolour broadband photometry, without the recourse to spectroscopy, to reveal the best candidates for the period bouncers. By adopting such an approach, we have already studied ~65 short-period CVs and have found solid evidence for very low-mass donor stars of very low luminosity in several of them.
In the end, I will also present the discovery of the accretor’s Roche lobe overflow in CVs (and possibly in a black-hole candidate) during their outbursts. I will also shortly discuss how this discovery can affect the theory of the late evolution of interacting binaries.

Place:
Auditorium 111, Chemistry & Farmacy, Building Ñ3

Date:
Friday 5th April 2019

Hour:
16:15