Identifying Blue Horizontal Branch Stars Using the z Filter

TL;DR

This paper introduces a novel photometric method using the Sloan z band to identify blue horizontal branch stars, enabling efficient selection from surveys lacking u band data.

Contribution

The study presents a new color-color photometry technique utilizing the Sloan z band for BHB star identification, expanding options for surveys without u band filters.

Findings

Achieves selection accuracy comparable to traditional methods.

Maintains necessary completeness for Galactic structure studies.

Effective for surveys without u band, like Pan-STARRS.

Abstract

In this paper we present a new method for selecting blue horizontal branch (BHB) candidates based on color-color photometry. We make use of the Sloan Digital Sky Survey z band as a surface gravity indicator and show its value for selecting BHB stars from quasars, white dwarfs and main sequence A type stars. Using the g, r, i, and z bands, we demonstrate that extraction accuracies on par with more traditional u, g, and r photometric selection methods may be achieved. We also show that the completeness necessary to probe major Galactic structure may be maintained. Our new method allows us to efficiently select BHB stars from photometric sky surveys that do not include a u band filter such as the Panoramic Survey Telescope and Rapid Response System.