New open cluster Cepheids in the VVV survey tightly constrain near-infrared period--luminosity relations

TL;DR

This study discovers four new open cluster Cepheids using the VVV survey, including the longest-period OC Cepheid, and refines near-infrared period-luminosity relations with an expanded sample, improving their precision.

Contribution

It presents the discovery of four new OC Cepheids, including the longest-period one, and provides improved near-infrared PLRs based on a larger, more accurate sample.

Findings

Discovered four new OC Cepheids, including the longest-period one.

Improved the precision of NIR PLRs by 40% in the J band.

NIR PLRs are consistent with previous determinations.

Abstract

Classical Cepheids are among the most useful Galactic and nearby extragalactic distance tracers because of their well-defined period--luminosity relations (PLRs). Open cluster (OC) Cepheids are important objects to independently calibrate these PLRs. Based on Data Release 1 of the {\sl VISTA} Variables in the V\'ia L\'actea survey, we have discovered four new, faint and heavily reddened OC Cepheids, including the longest-period OC Cepheid known, ASAS J180342$-$2211.0 in Teutsch 14a. The other OC--Cepheid pairs include NGC 6334 and V0470 Sco, Majaess 170 and ASAS J160125$-$5150.3, and Teutsch 77 and BB Cen. ASAS J180342$-$2211.0, with a period of $\log P = 1.623$ [days] is important to constrain the slope of the PLR. The currently most complete $JHK_{\rm s}$ Galactic Cepheid PLRs are obtained based on a significantly increased sample of 31 OC Cepheids, with associated uncertainties that are improved by 40 per cent compared with previous determinations (in the $J$ band). The NIR PLRs are in good agreement with previous PLRs determined based on other methods.