Stellar over-densities in the halo: the extent of the Virgo over-density

TL;DR

This paper maps the three-dimensional structure of the Virgo Over-density, revealing it consists of two filaments and a circular feature spanning 38 degrees in the sky, with detailed distance and size measurements.

Contribution

It provides the first detailed 3D mapping of the Virgo Over-density using RR Lyrae data and photometric surveys, identifying its complex filamentary structure.

Findings

The Virgo Over-density includes two filaments and a circular feature.

The filaments are at heliocentric distances of 20 and 17 kpc.

The features span 38 degrees in right ascension and declination.

Abstract

We map the three dimensional extent of the Virgo Over-density by combining distance information from RR Lyrae variables and projected spatial information from SEKBO (Keller et al. 2008) and Sloan Digital Sky Survey (SDSS) DR6 photometry. The Virgo Over-density is seen to comprise two filaments 14.5 x 3 degrees and 10 x 3 degrees and a circular structure 3 degrees in diameter. Together the three features span 38 degrees of right ascension and declinations of +2 to -15 degrees. RR Lyrae variables place the two filamentary features at heliocentric distances of 20 and 17 kpc respectively, with projected dimensions of 5 x 1 kpc and 3 x 1 kpc.