The Extinction Toward the Galactic Bulge from RR Lyrae Stars

TL;DR

This study measures the reddening and extinction law toward the Galactic bulge using RR Lyrae stars, providing key data for understanding interstellar dust and improving distance estimates.

Contribution

It offers a large dataset of reddenings for RR Lyrae stars and determines the extinction coefficient consistent with standard extinction laws.

Findings

Reddenings derived for 3525 RR Lyrae stars in the Galactic bulge.

The extinction coefficient R_{V,VR} is found to be 4.3 ± 0.2, aligning with standard extinction laws.

The results support the applicability of the standard extinction law in the Galactic bulge region.

Abstract

We present mean reddenings toward 3525 RR0 Lyrae stars from the Galactic bulge fields of the MACHO Survey. These reddenings are determined using the color at minimum $V$-band light of the RR0 Lyrae stars themselves and are found to be in general agreement with extinction estimates at the same location obtained from other methods. Using 3256 stars located in the Galactic Bulge, we derive the selective extinction coefficient $R_{V,VR}=A_V/E(V-R) = 4.3 \pm 0.2$. This value is what is expected for a standard extinction law with $R_{V,BV} = 3.1 \pm 0.3$.