Galactic Globular and Open Cluster Fiducial Sequences in the Pan-STARRS1 Photometric System

TL;DR

This paper provides empirical fiducial sequences for various Galactic star clusters in the Pan-STARRS1 photometric system, covering a wide metallicity range, aiding future stellar population studies and calibration efforts.

Contribution

It presents the first comprehensive set of fiducial sequences for Galactic clusters in the PS1 system, including multiple evolutionary stages and spanning a broad metallicity range.

Findings

Excellent agreement with previous studies in similar systems.

Fiducials serve as a basis for interpreting PS1 observations.

Constraints for empirical colour–Teff relations.

Abstract

We present the fiducial sequences of a sample of Galactic star clusters in the five bands of the Pan-STARRS1 (PS1) photometric system (g_P1, r_P1, i_P1, z_P1, y_P1). These empirical sequences -- which include the red giant and sub-giant branches, the main sequence, and the horizontal branch -- were defined from deep colour-magnitude diagrams reaching below the oldest main-sequence turn-offs of 13 globular and 3 old open clusters covering a wide range of metallicities (-2.4 < [Fe/H] < +0.4). We find excellent agreement for the nine clusters in common with previous studies in similar photometric systems when transformed to the PS1 system. Because the photometric and spectroscopic properties of these stellar populations are accurately known, the fiducials provide a solid basis for the interpretation of observations in the PS1 system, as well as valuable constraints to improve the empirical colour--$T_{eff}$ relations.