A new near-IR window of low extinction in the Galactic plane

TL;DR

This paper reports the discovery of a new low-extinction near-infrared window in the Galactic plane using VVV survey data, enabling better study of the Galaxy's far side.

Contribution

The identification and analysis of a previously unknown low-extinction window near the Galactic plane using near-IR imaging and extinction mapping.

Findings

Discovered a 30 arcmin low-extinction window at (l,b)= (347.4,-0.4) deg.

Measured mean near-IR extinction A_Ks=0.46 and reddening E(J-Ks)=0.95.

Red clump giants show bimodal distance distribution at approximately 11 and 15 kpc.

Abstract

The windows of low extinction in the Milky Way (MW) plane are rare but important because they enable us to place structural constraints on the opposite side of the Galaxy, which has hitherto been done rarely. We use the near-infrared (near-IR) images of the VISTA Variables in the V\'ia L\'actea (VVV) Survey to build extinction maps and to identify low extinction windows towards the Southern Galactic plane. Here we report the discovery of VVV WIN 1713$-$3939, a very interesting window with relatively uniform and low extinction conveniently placed very close to the Galactic plane. The new window of roughly 30 arcmin diameter is located at Galactic coordinates (l,b)= (347.4,-0.4) deg. We analyse the VVV near-IR colour-magnitude diagrams in this window. The mean total near-IR extinction and reddening values measured for this window are A_Ks=0.46 and E(J-Ks)=0.95. The red clump giants within the window show a bimodal magnitude distribution in the Ks band, with peaks at Ks=14.1 and 14.8 mag, corresponding to mean distances of D=11.0+/-2.4 and 14.8+/-3.6 kpc, respectively. We discuss the origin of these red clump overdensities within the context of the MW disk structure.