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Related papers: Spectroscopy of Bright QUEST RR Lyrae Stars: Veloc…

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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 report the detection of spatially distinct stellar density features near the apocenters of the Sagittarius (Sgr) stream's main leading and trailing arm. These features are clearly visible in a high-fidelity stellar halo map that is based…

Astrophysics of Galaxies · Physics 2017-08-02 Branimir Sesar , Nina Hernitschek , Marion I. P. Dierickx , Mark A. Fardal , Hans-Walter Rix

We present a sample of ~5,000 RR Lyrae stars selected from the recalibrated LINEAR dataset and detected at heliocentric distances between 5 kpc and 30 kpc over ~8,000 deg^2 of sky. The coordinates and light curve properties, such as period…

We investigate the relationship between several previously identified Galactic halo stellar structures in the direction of Virgo using imaging and spectroscopic observations of F turnoff stars and blue horizontal branch stars from the Sloan…

We present an update of a spectroscopic follow-up survey at low-resolution of a large number of RR Lyrae halo overdensity candidates found in the southern sky. The substructure candidates were identified in the RR Lyrae catalog of Torrealba…

Astrophysics of Galaxies · Physics 2016-07-07 S. Duffau , A. K. Vivas , C. Navarrete , M. Catelan , G. Hajdu , G. Torrealba , C. Cortes , V. Belokurov , S. Koposov , A. J. Drake

We present observations obtained with the AAT's 2dF wide field spectrograph AAOmega of K-type stars located within a region of the sky which contains the Virgo Over-Density and the leading arm of the Sagittarius Stream. On the basis of the…

Solar and Stellar Astrophysics · Physics 2015-06-04 A. R. Casey , S. C. Keller , G. Da Costa

We collected data on radial velocities and distances of galaxies to elucidate structure and kinematics of the filament attached to the Virgo cluster from south. In the region RA = [12.5 - 13.5]h, Dec = [-20 - 0]deg there are 171 galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Igor D. Karachentsev , Olga G. Nasonova

Iorio et al. (2018) mapped out the Milky Way halo using a sample of RR Lyrae stars drawn from a cross-match of Gaia with 2MASS. We investigate the significant residual in their model which we constrain to lie at Galactocentric radii…

Astrophysics of Galaxies · Physics 2018-11-28 D. Boubert , V. Belokurov , D. Erkal , G. Iorio

RR Lyrae stars are standard candles with characteristic photometric variability and serve as powerful tracers of Galactic structure, substructure, accretion history, and dark matter content. Here we report the discovery of distant RR Lyrae…

We present spectroscopic confirmation of the "Pisces Overdensity", also known as "Structure J", a photometric overdensity of RR Lyrae stars discovered by the Sloan Digital Sky Survey (SDSS) at an estimated photometric distance of ~85kpc. We…

We determine photometric metal abundance estimates for individual main-sequence stars in the Virgo Overdensity (VOD), which covers almost 1000 deg^2 on the sky, based on a calibration of the metallicity sensitivity of stellar isochrones in…

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…

(abridged) The velocity distribution f(v) of nearby stars is estimated, via a maximum- likelihood algorithm, from the positions and tangential velocities of a kinematically unbiased sample of 14369 stars observed by the HIPPARCOS satellite.…

Astrophysics · Physics 2010-04-06 Walter Dehnen

A survey of 380 sq. deg. of the sky with the 1m Schmidt telescope at the Observatorio Nacional de Llano del Halo and the QUEST camera has found 498 RR Lyrae variables lying from 4 to 60 kpc from the Sun. We describe the halo substructure…

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

Abridged: We estimate the distances to ~48 million stars detected by the Sloan Digital Sky Survey and map their 3D number density distribution in 100 < D < 20 kpc range over 6,500 deg^2 of sky. The data show strong evidence for a Galaxy…

Full space velocities are computed for a sample of 130 nearby RR Lyrae variables using both ground-based and Hipparcos proper motions. In many cases proper motions from multiple sources have been averaged to produce a significant…

Astrophysics · Physics 2009-10-30 John C. Martin , Heather L. Morrison

Virgo is a dynamically young galaxy cluster with substructure in its spatial and kinematic distribution. Here, we simultaneously study the phase-space distribution and the main characteristics of Virgo's galaxies, particularly its most…

Astrophysics of Galaxies · Physics 2018-09-21 Thorsten Lisker , Rukmani Vijayaraghavan , Joachim Janz , John S. Gallagher , Christoph Engler , Linda Urich

We have assembled a sample of halo stars in the solar neighborhood to look for halo substructure in velocity and angular momentum space. Our sample includes red giants, RR Lyrae, and red horizontal branch stars within 2.5 kpc of the Sun…

We use about 15,000 F/G nearby dwarf stars selected from the LAMOST pilot survey to map the U-V velocity distribution in the solar neighbourhood. An extreme deconvolution algorithm is applied to reconstruct an empirical multi-Gaussian…

Astrophysics of Galaxies · Physics 2014-12-17 Qiran Xia , Chao Liu , Yan Xu , Shude Mao , Shuang Gao , Yonghui Hou , Ge Jin , Yong Zhang

[Abridged] We present a medium-resolution spectroscopic survey of late-type giant stars at mid-Galactic latitudes of (30$^{\circ}<|b|<60^{\circ}$), designed to probe the properties of this population to distances of $\sim$9 kpc. Because M…