Fiducial Stellar Population Sequences for the u'g'r'i'z' System

TL;DR

This paper presents high-quality, homogeneous photometric fiducial sequences for various Galactic star clusters in the u'g'r'i'z' system, calibrated for accurate interpretation of stellar populations.

Contribution

It provides a comprehensive set of empirical fiducial sequences for multiple star clusters across a wide metallicity range in the u'g'r'i'z' system, calibrated with secondary standards.

Findings

Fiducial sequences extend from the red-giant tip to below the turnoff.

Sequences are accurately calibrated to the u'g'r'i'z' system.

Applicable for interpreting stellar populations in the u'g'r'i'z' photometric system.

Abstract

We describe an extensive observational project that has obtained high-quality and homogeneous photometry for a number of different Galactic star clusters (including M 92, M 13, M 3, M 71, and NGC 6791) spanning a wide range in metallicity (-2.3<[Fe/H]<+0.4), as observed in the u'g'r'i'z' passbands with the MegaCam wide-field imager on the Canada-France-Hawaii Telescope. By employing these purest of stellar populations, fiducial sequences have been defined from color-magnitude diagrams that extend from the tip of the red-giant branch down to approximately 4 magnitudes below the turnoff: these sequences have been accurately calibrated to the standard u'g'r'i'z' system via a set of secondary photometric standards located within these same clusters. Consequently, they can serve as a valuable set of empirical fiducials for the interpretation of stellar populations data in the u'g'r'i'z' system.