Near-infrared Mira Period-Luminosity Relations in M33

TL;DR

This study improves Mira variable star distance measurements in M33 by analyzing near-infrared light curves with advanced modeling, classifying stars, and deriving precise period-luminosity relations.

Contribution

It extends Gaussian process modeling to multiple bands, enabling better period determinations and classification of Mira variables in M33.

Findings

Derived Period-Luminosity relations for O-rich Miras in M33.

Determined M33 distance modulus as 24.80 ± 0.06 mag.

Enhanced light curve analysis method for variable star classification.

Abstract

We analyze sparsely-sampled near-infrared (JHKs) light curves of a sample of 1781 Mira variable candidates in M33, originally discovered using I-band time-series observations. We extend our single-band semi-parametric Gaussian process modeling of Mira light curves to a multi-band version and obtain improved period determinations. We use our previous results on near-infrared properties of candidate Miras in the LMC to classify the majority of the M33 sample into Oxygen- or Carbon-rich subsets. We derive Period-Luminosity relations for O-rich Miras and determine a distance modulus for M33 of 24.80 +- 0.06 mag.