The Orbital Period and Negative Superhumps of the Nova-Like Cataclysmic Variable V378 Pegasi

TL;DR

This study determines the orbital period and negative superhumps of V378 Pegasi, a nova-like cataclysmic variable, revealing a stable precessing, tilted accretion disk over several years.

Contribution

It provides the first detailed measurement of the orbital and superhump periods of V378 Pegasi, confirming the presence of negative superhumps and disk precession.

Findings

Orbital period of 0.13858 days identified.

Negative superhumps with a period of 0.1346 days observed.

Superhumps remained stable over several years.

Abstract

A radial velocity study is presented of the cataclysmic variable V378 Pegasi (PG 2337+300). It is found to have an orbital period of 0.13858 +/- 0.00004 d (3.32592 +/- 0.00096 hours). Its spectrum and long-term light curve suggest that V378 Peg is a nova-like variable, with no outbursts. We use the approximate distance and position in the Galaxy of V378 Peg to estimate E(B-V) = 0.095, and use near-infrared magnitudes to calculate a distance of 680 +/- 90 pc and M_V = 4.68 +/- 0.70, consistent with V378 Peg being a nova-like. Time-resolved photometry taken between 2001 and 2009 reveals a period of 0.1346 +/- 0.0004 d (3.23 +/- 0.01 hours). We identify this photometric variability to be negative superhumps, from a precessing, tilted accretion disk. Our repeated measurements of the photometric period of V378 Peg are consistent with this period having been stable between 2001 and 2009, with its negative superhumps showing coherence over as many as hundreds or even thousands of cycles.