The VMC Survey. XIX. Classical Cepheids in the Small Magellanic Cloud

TL;DR

This paper presents new near-infrared period-luminosity and related relations for Classical Cepheids in the Small Magellanic Cloud, including the first relations in the Y band and for second overtone pulsators, aiding distance measurements.

Contribution

It provides the first Y-band and second overtone Cepheid PL, PW, and PLC relations, and refines the SMC distance using near-infrared data, enhancing the calibration of cosmic distance scales.

Findings

First Y-band PL, PW, and PLC relations for Cepheids.

New near-infrared relations for second overtone pulsators.

Estimated SMC distance modulus of approximately 19.02 mag.

Abstract

The VISTA near infrared Y, J, Ks survey of the Magellanic System (VMC) is collecting deep Ks band time series photometry of pulsating variable stars hosted by the two Magellanic Clouds and their connecting Bridge. In this paper, we present Y, J, Ks light curves for a sample of 4172 Small Magellanic Cloud (SMC) Classical Cepheids (CCs). These data, complemented with literature V values, allowed us to construct a variety of period-luminosity (PL), period-luminosity-color (PLC), and period-wesenheit (PW) relationships, valid for Fundamental (F), First Overtone (FO) and Second Overtone (SO) pulsators. The relations involving V, J, Ks bands are in agreement with their counterparts in the literature. As for the Y band, to our knowledge we present the first CC PL, PW, and PLC relations ever derived using this filter. We also present the first near infrared PL, PW, and PLC relations for SO pulsators to date. We used PW(V,Ks) to estimate the relative SMC-LMC distance and, in turn, the absolute distance to the SMC. For the former quantity we find a value of Delta(mu)=0.55+-0.04 mag, in rather good agreement with other evaluations based on CCs, but significantly larger than the results obtained from older population II distance indicators. This discrepancy might be due to the different geometric distributions of young and old tracers in both Clouds. As for the absolute distance to the SMC, our best estimates are mu(SMC)=19.01+-0.05 mag and mu(SMC)=19.04+-0.06 mag, based on two distance measurements to the LMC, which rely on accurate CC and eclipsing Cepheid binary data, respectively.