Cepheids and Long Period Variables in M33

TL;DR

This paper presents a long-term photometric survey of M33 aiming to discover and analyze variable stars like Cepheids and long-period variables, with the goal of calibrating the Cepheid Period-Luminosity relation.

Contribution

It combines historical and new observations over 7 years to identify and characterize variable stars in M33, providing data for calibration of the Cepheid PL relation.

Findings

Representative light curves of variables in M33

Color-magnitude diagrams of observed stars

Optical Cepheid Period-Luminosity relations for M33

Abstract

We are conducting a long-term photometric survey of the nearby galaxy M33 to discover Cepheids, eclipsing binaries, and long-period variables. The dataset combines previously-obtained optical images from the DIRECT project with new observations acquired at the WIYN 3.5m telescope. The entire data set spans over 7 years with excellent synoptic coverage which will enable the discovery and characterization of stars displaying variability over a wide range of timescales (days, weeks, months, years). In this preliminary work we show representative light curves of different variables we found so far in two fields, color-magnitude diagrams, and optical Cepheid Period-Luminosity relations for M33. The ultimate goal of the project is to provide an absolute calibration of the Cepheid Period-Luminosity relation, and to study its metallicity dependence at optical wavelengths.