TIME-SERIES ANALYSIS OF FV SCUTI WITH TESS: ECLIPSE DETECTION AND PERIOD EVOLUTION

Abstract

Cataclysmic variables (CVs) are binary star systems where a White Dwarf (WD) accretes matter from a donor star, and that accreted matter typically forms an accretion disk around the WD. Classical novae, a subclass of CVs, are distinguished by sudden outbursts resulting from thermonuclear runaways on the surface of the WD. FV Scuti (Nova Scuti 1960), a classical nova discovered in 1960, has a maximum visual magnitude of ∼9.1 and faded by three magnitudes within approximately one month. Despite its historical detection, FV Sct has lacked a comprehensive modern investigation. Our study addresses this by analyzing Transiting Exoplanet Survey Satellite (TESS) light curves of FV Sct, specifically focusing on its quiescent behavior and orbital period evolution. TESS observed the system from June 18 to July 14, 2024, providing high-cadence (2- minute) photometric data. Following data reduction, which included detrending the light curve using the Locally Weighted Scatterplot Smoothing (LOWESS) method, we applied a Lomb-Scargle periodogram to determine the orbital period of the system, which is 7.33 hours. To assess period changes, we modeled primary eclipses and recorded the eclipsing time as observed time with inverted Gaussians fitting to the light curve and constructed an observed-minus-calculated (O-C) diagram. The quadratic fit in the O-C diagram yielded a period change rate of dP/dt = 2.474 × 10-7 days/day, indicating measurable orbital evolution potentially driven by angular momentum loss or mass transfer dynamics. These findings demonstrate FV Sct's ongoing activity in its post-nova phase and underscore TESS's value in long-term classical nova studies. Furthermore, the power density spectrum (PDS) reveals reduced high-frequency flickering, consistent with a cooler white dwarf, aligning with observations of other post-nova systems.