Template RR Lyrae H alpha, H beta, and H gamma Velocity Curves

TL;DR

This paper develops high-precision template radial velocity curves for RR Lyrae stars using Balmer lines, improving systemic velocity measurements crucial for large-scale galactic surveys.

Contribution

It introduces new template velocity curves for RR Lyrae stars based on high-precision measurements, reducing velocity measurement uncertainties.

Findings

Templates improve systemic velocity accuracy by up to 15 km/s.

Derived amplitude correlations enhance velocity and light curve analyses.

Applicable to large spectroscopic surveys like SDSS and LAMOST.

Abstract

We present template radial velocity curves of $ab$-type RR Lyrae stars constructed from high-precision measurements of ${\rm H\alpha}$, ${\rm H\beta}$, and ${\rm H\gamma}$ lines. Amplitude correlations between the Balmer line velocity curves, Johnson $V$-band, and SDSS $g$- and $r$-band light curves are also derived. Compared to previous methods, these templates and derived correlations reduce the uncertainty in measured systemic (center-of-mass) velocities of RR Lyrae stars by up to 15 {\kms}, and will be of particular interest to wide-area spectroscopic surveys such as the Sloan Digital Sky Survey (SDSS) and LAMOST Experiment for Galactic Understanding and Exploration (LEGUE).