Exploring Halo Substructure with Giant Stars: The Velocity Dispersion Profiles of the Ursa Minor and Draco Dwarf Spheroidal Galaxies at Large Angular Separations

2005 ◽  
Vol 631 (2) ◽  
pp. L137-L141 ◽  
Author(s):  
Ricardo R. Muñoz ◽  
Peter M. Frinchaboy ◽  
Steven R. Majewski ◽  
Jeffrey R. Kuhn ◽  
Mei-Yin Chou ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Dwarf Spheroidal Galaxies ◽  
Giant Stars ◽  
Ursa Minor ◽  
Spheroidal Galaxies

scholarly journals The Search for Dark Matter in Draco and Ursa Minor: A Three Year Progress Report

1987 ◽  
Vol 117 ◽  
pp. 153-160 ◽  
Author(s):  
M. Aaronson ◽  
E. Olszewski
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Progress Report ◽  
Radial Velocities ◽  
Circumstantial Evidence ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Stellar Velocity ◽  
Atmospheric Motions ◽  
Matter Component

We report the cumulative results of an on-going effort to measure the stellar velocity dispersion in two nearby dwarf spheroidal galaxies. Radial velocities having an accuracy ≲ 2 km s−1 have now been secured for ten stars in Ursa Minor and eleven stars in Draco (including 16 K giants and 5 C types). Most objects have been observed at two or more epochs. Stars having non-variable velocities yield in both dwarfs a large (∼ 10 km s−1) dispersion. These results cannot be explained by atmospheric motions, and circumstantial evidence suggests that the effects of undetected binaries are also not likely to be important. Instead, it seems that both spheroidals contain a substantial dark matter component, which therefore must be “cold” in form.

scholarly journals Evidence for Light-weight Local Group Dwarf Spheroidal Galaxies

2004 ◽  
Vol 220 ◽  
pp. 365-366
Author(s):  
J. R. Kuhn ◽  
D. Kocevski
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Local Group ◽  
Light Weight ◽  
Natural Explanation ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Matter Component ◽  
Morphological State ◽  
Spheroidal Galaxies

A simple and natural explanation for the dynamics and morphology of the Local Group Dwarf Spheroidal galaxies, Draco (Dra) and Ursa Minor (UMi), is that they are weakly unbound stellar systems with no significant dark matter component. A gentle, but persistent, Milky Way (MW) tide has left them in their current kinematic and morphological state (the “parametric tidal excitation”). A new test of a dark matter dominated dS potential follows from a careful observation of the “clumpiness” of the dS stellar surface density.

scholarly journals Too big to fail in light of Gaia

2019 ◽  
Vol 490 (1) ◽  
pp. 231-242 ◽  
Author(s):  
Manoj Kaplinghat ◽  
Mauro Valli ◽  
Hai-Bo Yu
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Large Scatter ◽  
Too Big To Fail ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Spheroidal Galaxies

ABSTRACT We point out an anticorrelation between the central dark matter (DM) densities of the bright Milky Way dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances inferred from Gaia data. The dSphs that have not come close to the Milky Way centre (like Fornax, Carina and Sextans) are less dense in DM than those that have come closer (like Draco and Ursa Minor). The same anticorrelation cannot be inferred for the ultrafaint dSphs due to large scatter, while a trend that dSphs with more extended stellar distributions tend to have lower DM densities emerges with ultrafaints. We discuss how these inferences constrain proposed solutions to the Milky Way’s too-big-to-fail problem and provide new clues to decipher the nature of DM.

The Draco and Ursa Minor Dwarf Spheroidal Galaxies: A Comparative Study

2002 ◽  
Vol 124 (6) ◽  
pp. 3222-3240 ◽  
Author(s):  
M. Bellazzini ◽  
F. R. Ferraro ◽  
L. Origlia ◽  
E. Pancino ◽  
L. Monaco ◽  
...  
Keyword(s):  
Comparative Study ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Spheroidal Galaxies

scholarly journals Kinematically Cold Populations at Large Radii in the Draco and Ursa Minor Dwarf Spheroidal Galaxies

2004 ◽  
Vol 611 (1) ◽  
pp. L21-L24 ◽  
Author(s):  
Mark I. Wilkinson ◽  
Jan T. Kleyna ◽  
N. Wyn Evans ◽  
Gerard F. Gilmore ◽  
Michael J. Irwin ◽  
...  
Keyword(s):  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Spheroidal Galaxies

scholarly journals Mass Modelling of dwarf Spheroidal Galaxies

2007 ◽  
Vol 3 (S244) ◽  
pp. 321-325
Author(s):  
Jarosław Klimentowski ◽  
Ewa L. Łokas ◽  
Stelios Kazantzidis ◽  
Francisco Prada ◽  
Lucio Mayer ◽  
...  
Keyword(s):  
Milky Way ◽  
Velocity Dispersion ◽  
Dwarf Galaxy ◽  
Data Sets ◽  
Kinematic Data ◽  
Dwarf Spheroidal Galaxies ◽  
Two Component ◽  
Tidal Tails ◽  
Better Than ◽  
Spheroidal Galaxies

AbstractWe study the origin and properties of unbound stars in the kinematic samples of dwarf spheroidal galaxies. For this purpose we have run a high resolution N-body simulation of a two-component dwarf galaxy orbiting in a Milky Way potential. We create mock kinematic data sets by observing the dwarf in different directions. When the dwarf is observed along the tidal tails the kinematic samples are strongly contaminated by unbound stars from the tails. However, most of the unbound stars can be removed by the method of interloper rejection proposed by den Hartog & Katgert. We model the velocity dispersion profiles of the cleaned-up kinematic samples using solutions of the Jeans equation. We show that even for such a strongly stripped dwarf the Jeans analysis, when applied to cleaned samples, allows us to reproduce the mass and mass-to-light ratio of the dwarf with accuracy typically better than 25%.

scholarly journals Proper Motions of Dwarf Spheroidal Galaxies fromHubble Space TelescopeImaging. III. Measurement for Ursa Minor

2005 ◽  
Vol 130 (1) ◽  
pp. 95-115 ◽  
Author(s):  
Slawomir Piatek ◽  
Carlton Pryor ◽  
Paul Bristow ◽  
Edward W. Olszewski ◽  
Hugh C. Harris ◽  
...  
Keyword(s):  
Proper Motions ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Spheroidal Galaxies
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