The hunt for old novae

TL;DR

This study advances the identification and classification of old classical novae using photometry and spectroscopy, increasing confirmed cases and determining new orbital periods, thereby enhancing understanding of post-nova systems.

Contribution

The paper reports an increase in confirmed old novae from 33 to 50 and provides new orbital period measurements for eight systems, including detailed analysis of V728 Sco.

Findings

Confirmed 17 new old novae in the southern and equatorial regions.

Determined orbital periods for eight old novae, including 3.32 hours for V728 Sco.

Identified V728 Sco as an eclipsing system with dwarf-nova-like outbursts.

Abstract

We inform on the progress of our on-going project to identify and classify old classical novae, using deep UBVR photometry and subsequent spectroscopy for a proper candidate confirmation, and time-resolved observations in order to find the orbital period and other physical properties of the identified old novae. This way, we have already increased the number of confirmed southern and equatorial post-novae from 33 to 50, and determined new orbital periods of eight objects. As an example, we summarise the results on V728 Sco (Nova Sco 1862) which we found to be an eclipsing system with a 3.32 h orbital period, displaying high and low states similar to dwarf-nova outbursts. Analysis of the low-state eclipse indicates the presence of a small hot inner disc around the white dwarf component.