J/ApJ/756/74 2MASS view of Sgr dSph. VII. Kinematics (Frinchaboy+, 2012)
A 2MASS all-sky view of the Sagittarius dwarf galaxy.
VII. Kinematics of the main body of the Sagittarius dSph.
Frinchaboy P.M., Majewski S.R., Munoz R.R., Law D.R., Lokas E.L.,
Kunkel W.E., Patterson R.J., Johnston K.V.
<Astrophys. J., 756, 74 (2012)>
=2012ApJ...756...74F 2012ApJ...756...74F
ADC_Keywords: Stars, M-type ; Stars, giant ; Radial velocities ; Galaxies, IR ;
Photometry, infrared
Keywords: galaxies: individual: Sgr dSph; galaxies: kinematics and dynamics;
Local Group
Abstract:
We have assembled a large-area spectroscopic survey of giant stars in
the Sagittarius (Sgr) dwarf galaxy core. Using medium resolution
(R∼15000), multifiber spectroscopy we have measured velocities of
these stars, which extend up to 12° from the galaxy's center (3.7
core radii or 0.4 times the King limiting radius). From these
high-quality spectra we identify 1310 Sgr members out of 2296 stars
surveyed, distributed across 24 different fields across the Sgr core.
Additional slit spectra were obtained of stars bridging from the Sgr
core to its trailing tail. Our systematic, large-area sample shows no
evidence for significant rotation, a result at odds with the ∼20km/s
rotation required as an explanation for the bifurcation seen in the
Sgr tidal stream; the observed small (≤4km/s) velocity trend
primarily along the major axis is consistent with models of the
projected motion of an extended body on the sky with no need for
intrinsic rotation. The Sgr core is found to have a flat velocity
dispersion (except for a kinematically colder center point) across its
surveyed extent and into its tidal tails, a property that matches the
velocity dispersion profiles measured for other Milky Way dwarf
spheroidal (dSph) galaxies. We comment on the possible significance of
this observed kinematical similarity for the dynamical state of the
other classical Milky Way dSphs in light of the fact that Sgr is
clearly a strongly tidally disrupted system.
Description:
Spectroscopic data were obtained using the Hydra spectrograph on the
Blanco 4m telescope at Cerro Tololo Inter-American Observatory (CTIO)
on the nights of 2003 July 19-22 and 2003 August 1-7. The spectral
range covered was 7740-8740Å with R∼15000.
We obtained supplementary data with the Modular Spectrograph on the
DuPont 2.5m telescope on the nights of UT 2003 September 19 and 20.
See section 5.1
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 92 2296 Sagittarius stellar velocity data
table5.dat 71 37 Supplementary radial velocity data on M giants
observed with the DuPont telescope
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/MNRAS/427/2647 : Sgr dSph stars spectral classification (McDonald+, 2012)
J/A+A/520/A95 : Abundances of red giants in M54 and Sgr dSph (Carretta+, 2010)
J/A+A/513/A62 : Sgr dSph VIMOS phot. and radial velocities (Giuffrida+, 2010)
J/ApJ/708/1290 : A 2MASS view of the Sgr dSph. VI. (Chou+, 2010)
J/A+A/465/815 : Abundances of Sgr dSph stars (Sbordone+, 2007)
J/ApJ/670/346 : M giant stars in the Sgr dwarf galaxy. V. (Chou+, 2007)
J/AJ/128/245 : M giant stars in the Sgr dwarf galaxy (Majewski+, 2004)
J/A+A/414/503 : Abundances in the Sgr dSph (Bonifacio+, 2004)
J/AJ/113/634 : The survival of Sagittarius dwarf galaxy (Ibata+ 1997)
J/AJ/110/1141 : Variables in the Sagittarius dSph (Mateo+ 1995)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Field Sagittarius field name (1)
10- 25 A16 --- 2MASS 2MASS identifier (HHMMSSss+DDMMSSs; J2000)
27- 31 F5.2 mag Kmag0 [8.8/14] Dereddened 2MASS K magnitude
33- 36 F4.2 mag (J-K)0 [0.5/1.4] Dereddened 2MASS J-K color index
38- 41 F4.2 mag E(B-V) [0.07/0.3] E(B-V) from Schlegel et al.
1998ApJ...500..525S 1998ApJ...500..525S
43- 49 F7.4 deg GLON Galactic Longitude
51- 58 F8.4 deg GLAT Galactic Latitude
60- 66 F7.3 deg Lambda [0.001/360] The Sgr longitude as viewed from
the Sun (Λ☉) (G1)
68- 73 F6.1 km/s HRV [-356.7/301.2] Heliocentric radial velocity
75- 80 F6.1 km/s Vgsr [-336.4/318.5] Galactocentric radial velocity
82- 84 F3.1 km/s e_HRV [1.2/5] Mean error on radial velocity
86- 90 F5.2 --- R [5/61] Tonry-Davis ratio (1979AJ.....84.1511T 1979AJ.....84.1511T)
92 A1 --- Mm [YN] Membership flag (Y=yes, N=no)
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Note (1): Field are:
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Field GLON GLAT <E(B-V)> spec
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Major+00 5.51 -14.21 0.154
Major-04 4.92 -10.11 0.197
Major-02 5.20 -12.26 0.170
Major+02 5.91 -15.99 0.121
Major+04 6.26 -17.90 0.101
Major+06 6.47 -20.02 0.119
Major+08 6.57 -22.04 0.088
Major+10 6.88 -24.05 0.159
Major+12 6.89 -26.15 0.176
Minor-03 2.57 -14.47 0.089
Minor-02 3.75 -14.21 0.125
Minor-01 4.62 -14.29 0.155
Minor+01 6.55 -13.94 0.162
Minor+02 7.77 -13.81 0.206
Minor+03 8.51 -13.56 0.219
Minor+05 10.69 -13.27 0.204
SE+04 3.27 -17.20 0.100
SE+02 4.46 -15.57 0.118
NW+02 6.94 -12.58 0.173
NW+04 7.81 -10.87 0.265
SW+04 2.28 -11.79 0.121
SW+02 4.08 -12.99 0.153
NE+02 7.50 -15.27 0.118
ESE+07 3.46 -20.02 0.095
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See Figure 1 and table 1 for further explanations.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS identifier (HHMMSSss+DDMMSSs; J2000)
18- 22 F5.2 mag Kmag0 [9.7/12.4] Dereddened 2MASS K magnitude
24- 27 F4.2 mag (J-K)0 [0.9/1.3] Dereddened 2MASS J-K color index
29- 32 F4.2 mag E(B-V) [0/0.2] E(B-V) from Schlegel et al.
1998ApJ...500..525S 1998ApJ...500..525S
34- 37 F4.1 deg GLON Galactic Longitude
39- 43 F5.1 deg GLAT Galactic Latitude
45- 48 F4.1 deg Lambda [12.7/48.2] The Sgr longitude as viewed from
the Sun (Λ☉) (G1)
50- 55 F6.1 km/s HRV [-133.2/144.2] Heliocentric radial velocity
57- 62 F6.1 km/s Vgsr [-120.7/165.7] Galactocentric radial velocity
64- 67 F4.2 --- CCP [0.2/0.95] Peak of the cross-correlation
spectrum
69 I1 --- Q [4/7] Data quality (7=best; 0=worst)
71 A1 --- Mm [YN] Membership flag (Y=yes, N=no)
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Global Notes:
Note (G1): The Sgr coordinate system is described in Majewski et al.
(2003ApJ...599.1082M 2003ApJ...599.1082M) and is defined by virtue of the orientation of
the extended tidal stream. However, we note that (as shown in that
same reference; see their Figure 7) the main body of Sgr is canted by
about 6° with respect to the mean orientation of the stream, so
that our major and minor axis positions do not directly line up with
the (Λ☉, B☉) system.
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History:
From electronic version of the journal
References:
Majewski et al. Paper I. 2003ApJ...599.1082M 2003ApJ...599.1082M
Majewski et al. Paper II. 2004AJ....128..245M 2004AJ....128..245M Cat. J/AJ/128/245
Johnston et al. Paper III. 2005ApJ...619..800J 2005ApJ...619..800J
Law et al. Paper IV. 2005ApJ...619..807L 2005ApJ...619..807L
Chou et al. Paper V 2007ApJ...670..346C 2007ApJ...670..346C Cat. J/ApJ/670/346
Chou et al. Paper VI. 2010ApJ...708.1290C 2010ApJ...708.1290C Cat. J/ApJ/708/1290
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Mar-2014