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  4. The kinematic status and mass content of the sculptor dwarf spheroidal galaxy
 
research article

The kinematic status and mass content of the sculptor dwarf spheroidal galaxy

Battaglia, G.
•
Helmi, A.
•
Tolstoy, E.
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2008
The Astrophysical Journal Letters

We present VLT FLAMES spectroscopic observations (R similar to 6500) in the Ca II triplet region for 470 probable kinematic members of the Sculptor (Scl) dwarf spheroidal galaxy. The accurate velocities (+/- 2 km s(-1)) and large area coverage of Scl allow us to measure a velocity gradient of 7.6(-2.2)(+3.0) km s(-1) deg(-1) along the projected major axis of Scl, likely a signature of intrinsic rotation. We also use our kinematic data to measure the mass distribution within this system. By considering independently the kinematics of the two distinct stellar components known to be present in Scl, we are able to relieve known degeneracies and find that the observed velocity dispersion profiles are best fitted by a cored dark matter halo with core radius kpc and mass enclosed within the gamma(c) = 0.5 kpc last measured point M(< 1.8 kpc) = (3.4 +/- 0.7) x 10(8) M-circle dot, assuming an increasingly radially anisotropic velocity, ellipsoid. This results in a mass-to-light ratio of 158 +/- 33 (M/L)(circle dot) inside 1.8 kpc. An NFW profile with concentration c = 20 and mass M(< 1.8 kpc) = 2.2(-0.7)(+1.0) x 10(8) M-circle dot is also statistically consistent with the ob- servations, but it tends to yield poorer fits for the metal-rich stars.

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Type
research article
DOI
10.1086/590179
Web of Science ID

WOS:000257660800004

Author(s)
Battaglia, G.
Helmi, A.
Tolstoy, E.
Irwin, M.
Hill, V.
Jablonka, P.  
Date Issued

2008

Published in
The Astrophysical Journal Letters
Volume

681

Start page

L13

End page

L16

Subjects

dark matter

•

galaxies : dwarf

•

galaxies : individual (Sculptor dwarf spheroidal) galaxies : kinematics and dynamics

•

Local Group

•

Exploring Halo Substructure

•

Dark-Matter

•

Giant Stars

•

Milky-Way

•

Field

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LASTRO  
Available on Infoscience
November 30, 2010
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/61232
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