J/MNRAS/439/1015 Velocities of red giants in 7 LG dwarf galaxies (Kirby+, 2014)
The dynamics of isolated Local Group galaxies.
Kirby E.N., Bullock J.S., Boylan-Kolchin M., Kaplinghat, M., Cohen J.G.
<Mon. Not. R. Astron. Soc. 439, 1015 (2014)>
=2014MNRAS.439.1015K 2014MNRAS.439.1015K
ADC_Keywords: Galaxies, nearby ; Radial velocities ; Velocity dispersion
Keywords: galaxies: dwarf - galaxies: kinematics and dynamics - Local Group
Abstract:
We measured velocities of 862 individual red giant stars in seven
isolated dwarf galaxies in the Local Group: NGC 6822, IC 1613, VV 124
(UGC 4879), the Pegasus dwarf irregular galaxy (DDO 216), Leo A,
Cetus, and Aquarius (DDO 210). We also computed velocity dispersions,
taking into account the measurement uncertainties on individual stars.
None of the isolated galaxies is denser than the densest Local Group
satellite galaxy. Furthermore, the isolated dwarf galaxies have no
obvious distinction in the velocity dispersion-half-light radius
plane from the satellite galaxies of the Milky Way and M31. The
similarity of the isolated and satellite galaxies' dynamics and
structural parameters imposes limitations on environmental solutions
to the too-big-to-fail problem, wherein there are fewer dense dwarf
satellite galaxies than would be expected from cold dark matter
simulations. This data set also has many other applications for dwarf
galaxy evolution, including the transformation of dwarf irregular into
dwarf spheroidal galaxies. We intend to explore these issues in future
work.
Description:
Velocities for 862 individual red giants in 7 different isolated dwarf
galaxies are presented. Spectra were obtained with the DEIMOS
spectrograph on the Keck II telescope. The resolving power of the
spectra is R∼7000, and the typical velocity measurement uncertainty is
3km/s. Stars are assigned yes-or-no membership on the basis of
position in the colour-magnitude diagram, presence of a strong NaI
8190 doublet, and radial velocity.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 68 862 Catalogue of velocities for 862 individual
stars in 7 dwarf galaxies
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See also:
J/AJ/133/2393 : UBVRI phot. in seven Local Group dwarfs galaxies (Massey+ 2007)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Galaxy Dwarf galaxy name: IC1613, NGC6822, VV124,
Pegasus, LeoA, Cetus or Aquarius.
10- 19 A10 --- Name Object name (1)
21- 22 I2 h RAh Hour of Right Ascension (J2000)
24- 25 I2 min RAm Minute of Right Ascension (J2000)
27- 31 F5.2 s RAs Second of Right Ascension (J2000)
33 A1 --- DE- Sign of the Declination (J2000)
34- 35 I2 deg DEd Degree of Declination (J2000)
37- 38 I2 arcmin DEm Arcminute of Declination (J2000)
40- 43 F4.1 arcsec DEs Arcsecond of Declination (J2000)
45- 49 F5.1 --- S/N Signal-to-noise ratio per Angstrom
51- 56 F6.1 km/s HRV Heliocentric radial velocity
58- 61 F4.1 km/s e_HRV [2/29] Error on HRV
63 A1 --- Mmb [YN] Membership status (Yes or No)
65- 68 A4 --- n_Mmb [Na v] Reason for non-membership (2)
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Note (1): Objects designated as:
IC1613 : B07-NNNNN
NGC6822 : M07-NNNNN, Massey et al., 2007, Cat. J/AJ/133/2393
VV124 : NNNNN
Pegasus : NNNNNN
LeoA : NNNNN
Cetus : M05-NNNN
Aquarius: NNNN
Note (2): Reason for non-membership as follows:
Na = equivalent width of the NaI doublet at 8183 and 8195Å exceed 1Å,
even after accounting for the error in the EW measurements.
v = based on velocity
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Acknowledgements:
Evan N. Kirby, ekirby(at)uci.edu
(End) Evan N. Kirby [UC Irvine, USA], Patricia Vannier [CDS] 07-Jan-2014