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Related papers: Stellar Halo Parameters from 4588 Subdwarfs

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Based on long baseline (5-7 years) multi-epoch HST/ACS photometry, used previously to measure the proper motion of M31, we present the proper motions (PMs) of 13 main-sequence Milky Way halo stars. The sample lies at an average distance of…

Astrophysics of Galaxies · Physics 2015-06-15 A. J. Deason , R. P. Van der Marel , P. Guhathakurta , S. T. Sohn , T. M. Brown

We present stellar radial velocity data for the Draco dwarf spheroidal galaxy obtained using the AF2/WYFFOS instrument combination on the William Herschel Telescope. Our dataset consists of 186 member stars, 159 of which have good quality…

Astrophysics · Physics 2009-11-07 J. T. Kleyna , M. I. Wilkinson , N. W. Evans , G. Gilmore

We confirm and extend the recent finding that the central surface density r_0*rho_0 galaxy dark matter halos, where r_0 and rho_0 are the halo core radius and central density, is nearly constant and independent of galaxy luminosity. Based…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 F. Donato , G. Gentile , P. Salucci , C. Frigerio Martins , M. I. Wilkinson , G. Gilmore , E. K. Grebel , A. Koch , R. Wyse

We study the formation histories and present-day structure of satellite galaxies formed in a high resolution hydrodynamic simulation of a Milky Way-like galaxy. The simulated satellites span nearly 4 orders of magnitude in luminosity but…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-06 Takashi Okamoto , Carlos S. Frenk

We use Canada-France-Hawaii Telescope Legacy Survey data for 170 deg^2, recalibrated and transformed to the Sloan Digital Sky Survey ugri photometric system, to study the distribution of near-turnoff main-sequence stars in the Galactic halo…

Astrophysics of Galaxies · Physics 2015-05-20 Branimir Sesar , Mario Juric , Zeljko Ivezic

We use simulations of Milky Way-sized dark matter haloes from the Aquarius Project to investigate the orbits of substructure haloes likely, according to a semi-analytic galaxy formation model, to host luminous satellites. These tend to…

Astrophysics of Galaxies · Physics 2015-06-17 Christopher Barber , Else Starkenburg , Julio Navarro , Alan McConnachie , Azadeh Fattahi

We present line-of-sight stellar velocity distributions of elliptical galaxy NGC 821 obtained to approximately 100 arcsec (over 2 effective radii) with long-slit spectroscopy from the Hobby-Eberly Telescope. Our measured stellar…

Astrophysics · Physics 2011-01-20 Amy Forestell , Karl Gebhardt

We use cosmological LCDM numerical simulations to model the evolution of the substructure population in sixteen dark matter haloes with resolutions of up to seven million particles within the virial radius. The combined substructure…

Astrophysics · Physics 2008-11-26 Darren Reed , Fabio Governato , Thomas Quinn , Jeffrey Gardner , Joachim Stadel , George Lake

We have obtained two-dimensional velocity fields of the dwarf spiral galaxy NGC 2976 in Halpha and CO. The high spatial (~75 pc) and spectral (13 km/s and 2 km/s, respectively) resolution of these observations, along with our multicolor…

Astrophysics · Physics 2009-11-10 Joshua D. Simon , Alberto D. Bolatto , Adam Leroy , Leo Blitz

We present a non-parametric, empirically based, model for associating galaxy luminosities with halo/subhalo masses, based on a self-consistent treatment of subhalo mass loss and the subhalo mass function. We find that, at high mass, the…

Astrophysics · Physics 2009-11-11 A. Vale , J. P. Ostriker

Properties of dark matter halos are reviewed. Taken from different publications, we present results on (1) the mass and velocity functions, (2) density and velocity profiles, and (3) concentration of halos. In the range of radii…

Astrophysics · Physics 2007-05-23 Anatoly Klypin

We present an analysis of the space motions of 742 subdwarf stars based on the sample of Carney et al. (1994, CLLA). Hipparcos parallaxes, TYC2+HIP proper motions and Tycho2 proper motions were combined with radial velocities and…

Astrophysics · Physics 2009-11-10 M. I. Arifyanto , B. Fuchs , H. Jahreiss , R. Wielen

We measure proper motions with the Hubble Space Telescope for 16 extreme radial velocity stars, mostly unbound B stars in the Milky Way halo. Twelve of these stars have proper motions statistically consistent with zero, and thus have radial…

Solar and Stellar Astrophysics · Physics 2015-06-23 Warren R. Brown , Jay Anderson , Oleg Y. Gnedin , Howard E. Bond , Margaret J. Geller , Scott J. Kenyon

The observed flaring of HI disk in the outer region of galaxies has been used in the past to determine the shape of the dark matter halo. Previous studies based on this concept suggest a slightly oblate halo (axis ratio ~ 0.8) for our…

Astrophysics · Physics 2009-11-11 C. A. Narayan , K. Saha , C. J. Jog

We present the discovery and spectroscopic identification of two very high proper motion ancient white dwarf stars, found in a systematic proper motion survey. Their kinematics and apparent magnitude clearly indicate that they are halo…

Astrophysics · Physics 2009-10-31 Rodrigo Ibata , Michael Irwin , Olivier Bienayme , Ralf Scholz , Jean Guibert

The last few months have seen the measurements of the radial velocities of all of the dwarf spheroidal companions to the Andromeda galaxy (M31) using the spectrographs (HIRES and LRIS) on the Keck Telescope. This paper summarises the data…

Astrophysics · Physics 2009-10-31 N. W. Evans , M. I. Wilkinson , P. Guhathakurta , E. K. Grebel , S. S. Vogt

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

The kinematics of satellite galaxies reflect the masses of the extended dark matter haloes in which they orbit, and thus shed light on the mass-luminosity relation (MLR) of their corresponding central galaxies. In this paper we select a…

Astrophysics · Physics 2009-11-19 Surhud More , Frank C. van den Bosch , Marcello Cacciato , Houjun Mo , Xiaohu Yang , Ran Li

We report the discovery of three nearby old halo white dwarf candidates in the Sloan Digital Sky Survey (SDSS), including two stars in a common proper motion binary system. These candidates are selected from our 2800 square degree proper…

We measure the rotation of the Milky Way stellar halo on two samples of Blue Horizontal Branch (BHB) field halo stars from the Sloan Digital Sky Survey (SDSS) with four different methods. The two samples comprise 1582 and 2563 stars…

Astrophysics of Galaxies · Physics 2015-06-15 Francesco Fermani , Ralph Schönrich