A comprehensive view of the Virgo Stellar Stream

Abstract

Radial velocities and metallicities have been measured for 82 RR Lyrae identified by the QUEST survey in the direction of the Virgo constellation. Distributed over 90 sq. deg. of the sky, they lie from 4 to 23 kpc from the Sun. Using an algorithm for finding groups in phase space and modeling the smooth halo component in the region, we identified the 5 most significant RRLS groups. We have examined the SEKBO and the Catalina catalog of RRLS (Prior et al. 2009, and Drake et al. 2013), as well as the bright QUEST RRLS sample (Vivas et al. in prep.), the catalogs of Blue Horizontal Branch stars compiled by Sirko et al (2004) and Brown et al (2008, 2010) and the catalog of Red Giant stars from the Spaghetti survey, for stars that may be related to the QUEST RRLS groups. The most significant group of RRLS is the Virgo Stellar Stream (VSS, Duffau et al 2006), group A, which is composed of at least 10 RRLS and 3 BHB stars. It has a mean distance of 19.6 kpc and a mean radial velocity Vgsr = 128 km/s, as estimated from its RRLS members. With the revised velocities reported here, there is no longer an offset in velocity between the RRLS in the VSS and the prominent peak in the velocities of main-sequence turnoff stars reported by Newberg et al (2007) in the same direction and at a similar distance (S297+63-20.5). The location in phase space of two other groups (F,H) suggests a possible connection with the VSS, which cannot be discarded at this point, although the turnoff colors of the VSS and group H, as identified from Newberg et al. (2007), suggest they might be composed of different populations. Two more groups (B,D), are found at mean distances of 19 and 5.7 kpc, and mean radial velocities of -94 and 32 km/s. None of our groups seems to relate to Sgr streams. The excess of stars observed in Virgo appears to be composed of several halo substructures along the same line of sight.

16 pages, 13 figures, 11 tables, Accepted for publication in A&A

References in corpus (9)

• The accretion origin of the Milky Way's stellar halo
• The Invisibles: A Detection Algorithm to Trace the Faintest Milky Way Satellites
• The QUEST RR Lyrae Survey II: The Halo Overdensities in the First Catalog
• The Overdensity in Virgo, Sagittarius Debris, and the Asymmetric Spheroid
• Revealing Substructure in the Galactic Halo - The SEKBO RR Lyrae Survey
• The Century Survey Galactic Halo Project III: A Complete 4300 deg^2 Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo
• Proper Motions in Kapteyn Selected Area 103: A Preliminary Orbit for the Virgo Stellar Stream
• Stellar over-densities in the halo: the extent of the Virgo over-density
• Spatial and Velocity clumping in an SDSS blue horizontal branch star catalogue

Cited by in corpus (12)

• Discovery of $\sim$ 9,000 new RR Lyrae in the Southern Catalina Surveys
• The Geometry of Sagittarius Stream from Pan-STARRS1 3$\pi$ RR Lyrae
• Disentangling the Galactic Halo with APOGEE: II. Chemical and Star Formation Histories for the Two Distinct Populations
• Tails and streams around the Galactic globular clusters NGC1851, NGC1904, NGC2298 and NGC2808
• The age structure of the Milky Way's halo
• On the use of field RR Lyrae as Galactic probes: IV. New insights into and around the Oosterhoff dichotomy
• Searching for tidal tails around $\omega$ Centauri using RR Lyrae Stars
• Disentangling the Virgo Overdensity with RR Lyrae stars
• The substructures in the local stellar halo from Gaia and LAMOST
• What is the Milky Way outer halo made of? High resolution spectroscopy of distant red giants
• Two substructures in the nearby stellar halo found in Gaia and RAVE
• An Orbit Fit to Likely Hermus Stream Stars