Nova V5116 Sgr and searching for superhumps in nova remnants

TL;DR

This study analyzes the orbital period of nova V5116 Sgr and investigates the presence of superhumps in nova remnants, providing insights into their binary characteristics and accretion structures.

Contribution

It reports the first orbital period measurement of V5116 Sgr and explores the occurrence of superhumps in nova remnants, highlighting the need for further observations.

Findings

V5116 Sgr has an orbital period of approximately 0.1238 days.

The system likely has a high inclination and lacks a fully developed accretion disc.

Most novae with expected superhumps do not show them, indicating the need for more data.

Abstract

We present the period analysis of unfiltered photometric observations of V5116 Sgr (Nova Sgr 2005 #2) and we search for superhump candidates in novae remnants. The PDM method for period analysis is used. The masses of the novae componets are estimated from the secondary mass -- orbital period and primary mass -- decline time relations. We found that 13 nights of V5116 Sgr observations in the year 2006 are modulated with a period of $0.1238 \pm 0.0001$ d ($2.9712 \pm 0.0024$ h). Following the shape of the phased light curves and no apparent change in the value of the periodicity in different subsamples of the data, we interpret the period as orbital in nature. The binary system then falls within the period gap of the orbital period distribution of cataclysmic variables. From the maximum magnitude -- rate of decline relation, we estimate the maximum absolute visual magnitude of $M_{\rm Vmax} = -8.85 \pm 0.04$ mag using the measured value of decline $t_{\rm 2} = 6.5 \pm 1.0$ d. The mass-period relation for cataclysmic variables yields a secondary mass estimate of about $0.26 \pm 0.05 {\rm M}_{\rm \odot}$. We propose that V5116 Sgr is a high inclination system showing an irradiation effect of the secondary star. No fully developed accretion disc up to the tidal radius with the value lower than $3.5 10^{10}$ cm is probable. The mass ratio was estimated in a few novae and the presence or absence of superhumps in these systems was compared with the mass ratio limit for superhumps of about 0.35. We found that in the majority of novae with expected superhumps, this variability has not been found yet. Therefore, more observations of these systems is encouraged.