2020A&A...633A..36M

Query : 2020A&A...633A..36M

2020A&A...633A..36M - Astronomy and Astrophysics, volume 633A36-36 (2020/1-1)

Stellar 3D kinematics in the Draco dwarf spheroidal galaxy.

MASSARI D., HELMI A., MUCCIARELLI A., SALES L.V., SPINA L. and TOLSTOY E.

Abstract (from CDS):


Aims. We present the first three-dimensional internal motions for individual stars in the Draco dwarf spheroidal galaxy.
Methods. By combining first-epoch Hubble Space Telescope observations and second-epoch Gaia Data Release 2 positions, we measured the proper motions of 149 sources in the direction of Draco. We determined the line-of-sight velocities for a sub-sample of 81 red giant branch stars using medium resolution spectra acquired with the DEIMOS spectrograph at the Keck II telescope. Altogether, this resulted in a final sample of 45 Draco members with high-precision and accurate 3D motions, which we present as a table in this paper.
Results. Based on this high-quality dataset, we determined the velocity dispersions at a projected distance of ∼120pc from the centre of Draco to be σR=11.0–1.5+2.1km/s, σT=9.9–3.1km/s and σLOS=9.0–1.1+1.1km/s in the projected radial, tangential, and line-of-sight directions. This results in a velocity anisotropy β=0.25-1.38_+0.47 at r ≥120pc. Tighter constraints may be obtained using the spherical Jeans equations and assuming constant anisotropy and Navarro-Frenk-White (NFW) mass profiles, also based on the assumption that the 3D velocity dispersion should be lower than ~=1/3 of the escape velocity of the system. In this case, we constrain the maximum circular velocity Vmax of Draco to be in the range of 10.2-17.0km/s. The corresponding mass range is in good agreement with previous estimates based on line-of-sight velocities only.
Conclusions. Our Jeans modelling supports the case for a cuspy dark matter profile in this galaxy. Firmer conclusions may be drawn by applying more sophisticated models to this dataset and with new datasets from upcoming Gaia releases.

Abstract Copyright: © ESO 2020

Journal keyword(s): galaxies: dwarf - Local Group - galaxies: kinematics and dynamics - proper motions - techniques: radial velocities

VizieR on-line data: <Available at CDS (J/A+A/633/A36): table2.dat table3.dat>

Simbad objects: 84

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Number of rows : 84
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1498 4
2 SDSS J171916.61+575808.7 * 17 19 16.6092274728 +57 58 08.765030532     19.224   18.131 ~ 4 0
3 Gaia DR3 1433205297908025984 * 17 19 17.4234605067 +57 57 50.780819449           ~ 1 0
4 SDSS J171922.01+575902.7 * 17 19 22.0121011752 +57 59 02.713220160   19.883 19.259 18.872 18.380 ~ 6 0
5 Gaia DR3 1433202308610765440 * 17 19 22.8116333223 +57 56 52.376442231           ~ 1 0
6 SDSS J171925.66+575705.6 * 17 19 25.6543283328 +57 57 05.594215068   20.057 19.372 18.949 18.434 ~ 6 0
7 Gaia DR3 1433206878456195328 * 17 19 26.3638188752 +57 59 35.588369764           ~ 1 0
8 Gaia DR3 1433206814031480064 * 17 19 26.6719050028 +57 58 51.315738010           ~ 1 0
9 Gaia DR3 1433206809736718720 * 17 19 27.4975409115 +57 59 04.771636431           ~ 1 0
10 Gaia DR3 1433203579921078528 * 17 19 27.5334347848 +57 56 39.329527036           ~ 1 0
11 Gaia DR3 1433206878456195584 * 17 19 28.0063749116 +57 59 39.043028783           ~ 1 0
12 Gaia DR3 1433206882752450688 * 17 19 28.5148329739 +57 59 56.538039079           ~ 1 0
13 Gaia DR3 1433206809736538240 * 17 19 29.3377306629 +57 58 46.576265175           ~ 1 0
14 Gaia DR3 1433206809736544000 * 17 19 30.9470939495 +57 58 59.048723573           ~ 1 0
15 SDSS J171933.23+575637.9 * 17 19 33.2369534616 +57 56 37.986575820     19.571   18.550 ~ 3 0
16 Gaia DR3 1433203614280848128 * 17 19 37.0037761020 +57 57 47.227616492           ~ 1 0
17 SDSS J171938.57+575801.1 * 17 19 38.5822057584 +57 58 01.163788356     18.880   17.795 ~ 4 0
18 Gaia DR3 1433203923518513792 * 17 19 40.6262364076 +57 58 38.687257032           ~ 1 0
19 Gaia DR3 1433203614280856448 * 17 19 41.0661128901 +57 58 05.492941222           ~ 1 0
20 Gaia DR3 1433203923518519808 * 17 19 41.1660299492 +57 58 51.910479193           ~ 1 0
21 Gaia DR3 1433203614280847360 * 17 19 41.1845431150 +57 57 42.657014990           ~ 1 0
22 Z 300-12 G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1428 1
23 [BFO2002] Dra 10362 * 17 20 30.5109200640 +57 55 03.134758656     19.231   18.134 ~ 3 0
24 Gaia DR3 1433160909421019392 * 17 20 32.7601945218 +57 54 28.130284310           ~ 1 0
25 2MASS J17203416+5754132 * 17 20 34.1674533504 +57 54 13.169945736           ~ 2 0
26 Gaia DR3 1433160909421021184 * 17 20 34.7320560282 +57 54 34.713783992           ~ 1 0
27 [BFO2002] Dra 11038 * 17 20 34.9394298984 +57 55 34.221585432     19.904   17.750 ~ 2 0
28 SDSS J172035.32+575407.3 * 17 20 35.3222357640 +57 54 07.343807400     19.188   18.060 ~ 4 0
29 Gaia DR3 1433160905125985024 * 17 20 35.8482447862 +57 54 32.513537526           ~ 1 0
30 SDSS J172036.31+575539.0 * 17 20 36.3093288624 +57 55 39.050165352     19.342   18.269 ~ 3 0
31 Gaia DR3 1433160698967534208 * 17 20 36.5281844650 +57 53 45.129443588           ~ 1 0
32 [BFO2002] Dra 11019 * 17 20 37.5647149200 +57 55 19.217179956   20.370 19.696 19.283 18.791 ~ 4 0
33 SDSS J172038.25+575448.2 * 17 20 38.2527119040 +57 54 48.249474660   20.083 19.391 18.966 18.459 ~ 6 0
34 SDSS J172038.33+575532.2 * 17 20 38.3324680848 +57 55 32.221001208   20.373 19.686 19.263 18.755 ~ 7 0
35 Gaia DR3 1433160698967550080 * 17 20 38.9783947742 +57 54 22.472121867           ~ 1 0
36 SDSS J172039.20+575557.4 * 17 20 39.1969886424 +57 55 57.417450384   20.998 20.369 19.982 19.499 ~ 6 0
37 [KGS2010] Dra 630386 * 17 20 39.2899851360 +57 55 41.456261964     20.174   19.331 ~ 3 0
38 SDSS J172039.62+575307.7 * 17 20 39.6181849320 +57 53 07.668162672     20.552   19.527 ~ 3 0
39 Gaia DR3 1433160939485733888 * 17 20 39.6551407781 +57 54 53.351908263           ~ 1 0
40 Gaia DR3 1433160630250368256 * 17 20 39.8840217422 +57 53 04.767137014           ~ 1 0
41 Gaia DR3 1433160939485729664 * 17 20 39.9110393763 +57 54 45.780675033           ~ 1 0
42 SDSS J172039.94+575335.8 * 17 20 39.9434752416 +57 53 35.802521988     19.500   18.490 ~ 3 0
43 Gaia DR3 1433160943781778176 * 17 20 40.0247064600 +57 55 09.103575787           ~ 1 0
44 [BFO2002] Dra 10328 * 17 20 40.7618384616 +57 53 19.312176588   19.842 19.219 18.836 18.361 ~ 4 0
45 Gaia DR3 1433161008205244160 * 17 20 41.6085388091 +57 56 13.027314778           ~ 1 0
46 Gaia DR3 1433160733327526144 * 17 20 42.4202131006 +57 54 20.705535794           ~ 1 0
47 [BFO2002] Dra 10867 * 17 20 42.5150846472 +57 52 47.687802708   20.680 20.030 19.634 19.158 ~ 4 0
48 Gaia DR3 1433160943781778688 * 17 20 42.5796258306 +57 55 03.241821651           ~ 1 0
49 Gaia DR3 1433157709670279296 * 17 20 43.6308179957 +57 52 57.655915491           ~ 1 0
50 Gaia DR3 1433160939485754880 * 17 20 43.6865681968 +57 55 41.840408551           ~ 1 0
51 Gaia DR3 1433160733327296768 * 17 20 43.8403938596 +57 54 37.346396943           ~ 1 0
52 SDSS J172044.28+575526.2 * 17 20 44.2815058608 +57 55 26.224546260     19.935   18.893 ~ 3 0
53 SDSS J172044.49+575511.6 * 17 20 44.4884407872 +57 55 11.620024608     20.028   18.978 ~ 4 0
54 SDSS J172044.73+575459.3 * 17 20 44.7286624584 +57 54 59.343683616   19.798 19.057 18.617 18.147 ~ 8 0
55 Gaia DR3 1433160943780773120 * 17 20 45.8790523303 +57 55 40.162241994           ~ 1 0
56 Gaia DR3 1433160939485747968 * 17 20 45.8890010550 +57 55 24.151973662           ~ 1 0
57 Gaia DR3 1433160664607803520 * 17 20 46.7151633553 +57 54 00.887629764           ~ 1 0
58 SDSS J172047.57+575408.4 * 17 20 47.5672030584 +57 54 08.402830704   19.561 18.847 18.408 17.895 ~ 7 0
59 SDSS J172047.78+575324.1 * 17 20 47.7766745352 +57 53 24.163387800   20.404 19.721 19.300 18.794 ~ 6 0
60 SDSS J172048.12+575456.4 * 17 20 48.1183739832 +57 54 56.468802420     18.734   17.579 ~ 4 0
61 Gaia DR3 1433161111284474240 * 17 20 49.8365912392 +57 56 46.116596878           ~ 1 0
62 Gaia DR3 1433157817045586048 * 17 20 51.2631976589 +57 54 11.454350695           ~ 1 0
63 [SSD2016] 51 QSO 17 20 52.3038815424 +57 55 13.175889672     19.836   19.279 ~ 6 0
64 SDSS J172052.51+575510.5 * 17 20 52.5112872744 +57 55 10.540344216     19.982   18.937 ~ 4 0
65 2MASS J17205298+5755578 Pe* 17 20 52.9916680392 +57 55 57.753374232   18.250 17.313 16.394 15.643 ~ 22 0
66 SDSS J172053.00+575627.7 * 17 20 52.9922664024 +57 56 27.709217736     19.087   17.978 ~ 4 0
67 [BFO2002] Dra 11094 * 17 20 53.4367747176 +57 56 20.564435148   20.641 19.975 19.565 19.066 ~ 4 0
68 2MASS J17205373+5754404 * 17 20 53.7355321848 +57 54 40.390335972     17.937   16.632 ~ 9 0
69 SDSS J172054.18+575519.9 * 17 20 54.1807037112 +57 55 19.886283336     19.850   18.773 ~ 3 0
70 Gaia DR3 1433158396865349504 * 17 21 27.8539256288 +57 57 19.021888151           ~ 1 0
71 Gaia DR3 1433158396865166592 * 17 21 28.2763597717 +57 57 23.723727923           ~ 1 0
72 Gaia DR3 1433159599455992832 * 17 21 33.3645248517 +57 56 40.228038761           ~ 1 0
73 Gaia DR3 1433159599455987840 * 17 21 35.0719648462 +57 56 28.669836517           ~ 1 0
74 Gaia DR3 1433159874334107008 * 17 21 36.1594226497 +57 58 14.665947259           ~ 1 0
75 Gaia DR3 1433159603751999744 * 17 21 38.7791922674 +57 56 57.282555144           ~ 1 0
76 SDSS J172139.01+575755.1 RG* 17 21 39.0148874160 +57 57 55.212944040   20.858 20.189 19.775 19.267 ~ 5 0
77 SDSS J172141.79+575550.7 * 17 21 41.7935589600 +57 55 50.717654184   19.691 18.977 18.534 17.998 ~ 6 0
78 2MASS J17214368+5757126 RG* 17 21 43.7161768632 +57 57 12.545635572   18.081 17.145 16.565 15.929 ~ 11 0
79 Gaia DR3 1433158916557233024 * 17 21 47.8294601137 +57 56 47.344496676           ~ 1 0
80 SDSS J172148.02+575732.5 * 17 21 48.0233688960 +57 57 32.523835212           ~ 2 0
81 SDSS J172149.54+575721.0 * 17 21 49.5386030064 +57 57 21.080086560           ~ 2 0
82 SDSS J172149.94+575817.0 RG* 17 21 49.9405555032 +57 58 17.094400608   20.665 19.999 19.592 19.102 ~ 5 0
83 SDSS J172155.21+575659.3 RG* 17 21 55.2138158640 +57 56 59.307835308   20.234 19.540 19.124 18.659 ~ 5 0
84 NAME Local Group GrG ~ ~           ~ 9325 0

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