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Related papers: Spectroscopy of QUEST RR Lyrae Variables: the new …

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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…

Astrophysics of Galaxies · Physics 2014-07-02 Sonia Duffau , A. Katherina Vivas , Robert Zinn , René Méndez , María Teresa Ruiz

A subset of the RR Lyrae (RRL) candidates identified from the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey data has been followed up photometrically (n=106) and spectroscopically (n=51). Period and light curve fitting reveals a 24…

Astrophysics · Physics 2015-05-13 Sayuri L Prior , G S Da Costa , Stefan C Keller , Simon J Murphy

Sixteen RR Lyrae variables from the QUEST survey that lie in the leading arm of the tidal stream from the Sagittarius dSph galaxy have been observed spectroscopically to measure their radial velocities and metal abundances. The systemic…

Astrophysics · Physics 2007-05-23 A. Katherina Vivas , Robert Zinn , Carme Gallart

Using a sample of 43 bright (V<16.1, distance <13 kpc) RR Lyrae stars (RRLS) from the QUEST survey with spectroscopic radial velocities and metallicities, we find that several separate halo substructures contribute to the Virgo overdensity…

We have measured the periods and light curves of 148 RR Lyrae variables from V=13.5 to 19.7 from the first 100 sq. degrees of the QUEST RR Lyrae survey. Approximately 55% of these stars belong to the clump of stars detected earlier by the…

A sample of RR Lyrae (RRL) variables from the Southern Edgeworth-Kuiper Belt Object survey in regions overlapping the expected position of debris from the interaction of the Sagittarius (Sgr) dwarf galaxy with the Milky Way (RA ~ 20 and…

Astrophysics of Galaxies · Physics 2014-11-20 Sayuri L Prior , G S Da Costa , Stefan C Keller

We use a combination of spatial distribution and radial velocity to search for halo sub-structures in a sample of 412 RR Lyrae stars (RRLS) that covers a $\sim 525$ square degrees region of the Virgo Overdensity (VOD) and spans distances…

Astrophysics of Galaxies · Physics 2016-11-15 A. Katherina Vivas , Robert Zinn , John Farmer , Sonia Duffau , Yiding Ping

We discuss the first part of a survey for RR Lyrae variables in the galactic halo that is being made with the 1m Schmidt telescope at the Venezuelan National Observatory. So far the survey has discovered 497 variables in 380 sq. degrees,…

Astrophysics · Physics 2007-05-23 A. Katherina Vivas , Robert Zinn

We present evidence for eight new clumps of blue horizontal branch (BHB) stars discovered in a catalogue of these stars compiled from the Sloan Digital Sky Survey (SDSS) by Sirko et al. published in 2004. Clumps are identified by selecting…

Astrophysics · Physics 2009-10-08 L. Clewley , T. D. Kinman

We discuss the density and radial velocity distributions of over 3000 candidate RR Lyrae stars selected by various methods using Sloan Digital Sky Survey data for about 1000 deg^2 of sky. This is more than 20 times larger sample than…

We present the first detailed chemical abundances for distant RR Lyrae stars members of the Virgo Stellar Stream (VSS), derived from X-Shooter medium-resolution spectra. Sixteen elements from carbon to barium have been measured in six VSS…

Astrophysics of Galaxies · Physics 2016-03-24 S. Duffau , L. Sbordone , A. K. Vivas , C. J. Hansen , M. Zoccali , M. Catelan , D. Minniti , E. K. Grebel

We present 2-degree field spectroscopic observations of a sample of 96 A-type stars selected from the Sloan Digital Sky Survey Data Release 3 (SDSS DR3). Our aim is to identify blue horizontal branch (BHB) stars in order to measure the…

Astrophysics · Physics 2009-11-11 L. Clewley , Matt J. Jarvis

A search for RR Lyrae stars (RRLS) in 840 sq.deg. of the sky in right ascension 150 - 210 deg and declination -10 - +10 deg yielded 1013 type ab and 359 type c RRLS. This sample is used to study the density profile of the Galactic halo,…

Astrophysics of Galaxies · Physics 2015-06-18 R. Zinn , B. Horowitz , A. K. Vivas , C. Baltay , N. Ellman , E. Hadjiyska , D. Rabinowitz , L. Miller

We have measured radial velocities and metallicities of 16 RR Lyrae stars, from the QUEST survey, in the Sagittarius tidal stream at 50 kpc from the galactic center. The distribution of velocities is quite narrow (std dev=25 km/s)…

Astrophysics · Physics 2007-05-23 A. Katherina Vivas , Robert Zinn , Carme Gallart

We present VLT-FORS1 spectra of a sample of 34 faint 20.0 < g* < 21.1 A-type stars selected from the Sloan Digital Sky Survey Early Data Release, with the goal of measuring the velocity dispersion of blue horizontal branch (BHB) stars in…

Astrophysics · Physics 2008-11-26 L. Clewley , S. J. Warren , P. C. Hewett , John. E. Norris , M. I. Wilkinson , N. W. Evans

We present results for the QUEST RR Lyrae Survey at low galactic latitude, conducted entirely with observations obtained with the QUEST mosaic camera and the 1.0/1.5m J\"urgen Stock Schmidt telescope at the National Observatory of…

Astrophysics of Galaxies · Physics 2015-06-11 Cecilia Mateu , A. Katherina Vivas , Juan José Downes , César Briceño , Robert Zinn , Gustavo Cruz-Diaz

The first catalog of the RR Lyrae stars (RRLS) in the Galactic halo by the QUEST Survey has been searched for significant overdensities that may be debris from disrupted dwarf galaxies or globular clusters. Away from the major…

Astrophysics · Physics 2008-11-26 A. Katherina Vivas , Robert Zinn

The latest results of the QUEST survey for RR Lyrae stars are described. This survey, which is designed to find and characterize sub-structures in the halo of our Galaxy, has covered about 700 square degrees of the sky and has detected 693…

Astrophysics · Physics 2007-05-23 A. Katherina Vivas , R. Zinn , Y. Subero , J. Hernandez

We present a search for RR Lyrae variable stars from archival observations of the Southern Edgeworth-Kuiper Belt Object survey. The survey covers 1675 square degrees along the ecliptic to a mean depth of V=19.5, i.e. a heliocentric distance…

Astrophysics · Physics 2009-11-13 Stefan C. Keller , Simon Murphy , Sayuri Prior , Gary DaCosta , Brian Schmidt

We isolate samples of 733 bright (g < 18) and 437 faint (g > 18) high-Galactic latitude blue horizontal branch stars with photometry and spectroscopy in the Sloan Digital Sky Survey (SDSS). Comparison of independent photometric and…

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