EM Cygni: a study of its eclipse timings

TL;DR

This paper presents new eclipse timings for EM Cygni, updates its orbital period analysis, and estimates the mass transfer rate, clarifying previous conflicting reports and confirming the rate's consistency with spectroscopic data.

Contribution

It provides accurate eclipse timings, resolves previous period variation conflicts, and estimates the mass transfer rate aligning with spectroscopic measurements.

Findings

Updated O-C diagram for EM Cygni

Mass transfer rate is below the critical value

Mass transfer rate matches spectroscopic estimates

Abstract

EM Cygni is a Z Cam-subtype eclipsing dwarf nova. Its orbital period variations were reported in the past but the results were in conflict to each other while other studies allowed the possibility of no period variation. In this study we report accurate new times of minima of this eclipsing binary and update its O-C diagram. We also estimate the mass transfer rate in EM Cygni system and conclude that the mass transfer is far from the critical value. The mass transfer rate determined from the eclipse timings is in agreement with the spectroscopically determined value.