2000MNRAS.317..348G


Query : 2000MNRAS.317..348G

2000MNRAS.317..348G - Mon. Not. R. Astron. Soc., 317, 348-374 (2000/September-2)

Stellar dynamics in the Galactic Centre: proper motions and anisotropy.

GENZEL R., PICHON C., ECKART A., GERHARD O.E. and OTT T.

Abstract (from CDS):

We report a new analysis of the stellar dynamics in the Galactic Centre, based on improved sky and line-of-sight velocities for more than 100 stars in the central few arcseconds from the black hole candidate SgrA*. The main results are as follows.

(1) Overall, the stellar motions do not deviate strongly from isotropy. For those 32 stars with a determination of all three velocity components, the absolute, line-of-sight and sky velocities are in good agreement, consistent with a spherical star cluster. Likewise the sky-projected radial and tangential velocities of all 104 proper motion stars in our sample are also consistent with overall isotropy.

(2) However, the sky-projected velocity components of the young, early-type stars in our sample indicate significant deviations from isotropy, with a strong radial dependence. Most of the bright Hei emission-line stars at separations from 1 to 10arcsec from SgrA* are on tangential orbits. This tangential anisotropy of the Hei stars and most of the brighter members of the IRS 16 complex is largely caused by a clockwise (on the sky) and counter-rotating (line of sight, compared to the Galaxy), coherent rotation pattern. The overall rotation of the young star cluster may be a remnant of the original angular momentum pattern in the interstellar cloud from which these stars were formed.

(3) The fainter, fast-moving stars within ~1arcsec of SgrA* may be largely moving on radial or very elliptical orbits. We have so far not detected deviations from linear motion (i.e., acceleration) for any of them. Most of the SgrA* cluster members are also on clockwise orbits. Spectroscopy indicates that they are early-type stars. We propose that the SgrA* cluster stars are those members of the early-type cluster that happen to have small angular momentum, and thus can plunge to the immediate vicinity of SgrA*.

(4) We derive an anisotropy-independent estimate of the Sun-Galactic Centre distance between 7.8 and 8.2kpc, with a formal statistical uncertainty of ±0.9kpc.

(5) We explicitly include velocity anisotropy in estimating the central mass distribution. We show how Leonard-Merritt and Bahcall-Tremaine mass estimates give systematic offsets in the inferred mass of the central object when applied to finite concentric rings for power-law clusters. Corrected Leonard-Merritt projected mass estimators and Jeans equation modelling confirm previous conclusions (from isotropic models) that a compact central mass concentration (central density ≥1012.6M.pc–3) is present and dominates the potential between 0.01 and 1pc. Depending on the modelling method used, the derived central mass ranges between 2.6x106 and 3.3x106M for R=8.0kpc.


Abstract Copyright: 2000, Royal Astronomical Society

Journal keyword(s): celestial mechanics, stellar dynamics - stars: kinematics - Galaxy: centre - Galaxy: kinematics and dynamics

Nomenclature: Table 1, col(1): [GPE2000] NN.NNA N=299. Table 1, col(19): GCIRS NWWN N=6 added. Table 1, col(19): [EG97] SNN (Nos S18-S19) added.

CDS comments: Table 1, col(19): w217 ?? ID not identified (= [GPE2000] 1.34)

Simbad objects: 95

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Number of rows : 95
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 M 106 Sy2 12 18 57.620 +47 18 13.39   9.14 8.41 8.11   ~ 2274 3
2 GCIRS 26 * 17 45 34.6 -29 00 13           ~ 4 0
3 GCIRS 11NE * 17 45 39.30 -29 00 14.3           ~ 7 0
4 BHA 2 * 17 45 39.31 -29 00 39.8           ~ 3 0
5 GCIRS 11SW * 17 45 39.36 -29 00 16.5           M3III 4 0
6 [BSD96] 22 WR* 17 45 39.38 -29 00 33.4           WC8/9 28 0
7 GCIRS 6W * 17 45 39.38 -29 00 26.2           ~ 16 0
8 [BSD96] 29 WR* 17 45 39.46 -29 00 31.7           WN8 29 0
9 BHA 4 IR 17 45 39.50 -29 00 22.4           ~ 3 0
10 [BSD96] 33 WR* 17 45 39.54 -29 00 35.0           Ofpe/WN9 41 0
11 BHA 4W * 17 45 39.58 -29 00 22.6           M7III 7 0
12 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13453 0
13 BHA 4E * 17 45 39.66 -29 00 22.8           M2III 8 0
14 GCIRS 2S * 17 45 39.69 -29 00 32.5           ~ 17 0
15 GCIRS 13E Cl* 17 45 39.73 -29 00 29.7           WN9 112 0
16 GCIRS 34W WR* 17 45 39.73 -29 00 26.6           Ofpe/WN9 58 0
17 BHA 7 * 17 45 39.77 -29 00 44.1           ~ 3 0
18 GCIRS 13W * 17 45 39.78 -29 00 30.5           M0III 20 0
19 GCIRS 3 * 17 45 39.80 -29 00 23.9           ~ 144 0
20 GCIRS 12S * 17 45 39.86 -29 00 37.4           M4III 15 0
21 GCIRS 12N * 17 45 39.86 -29 00 35.7           M0III 57 0
22 GCIRS 7W WR* 17 45 39.86 -29 00 22.2           WC9 38 0
23 [GEO97] W16 * 17 45 39.863 -29 00 29.01           ~ 6 0
24 GCIRS 29S2 * 17 45 39.8921 -29 00 27.209           K-M 11 0
25 GCIRS 29S * 17 45 39.91 -29 00 27.3           K3III 21 0
26 [GEO97] W7 V* 17 45 39.9150 -29 00 27.958           O9/9.5III? 17 0
27 GCIRS 29N WR* 17 45 39.917 -29 00 26.71           WC9 55 0
28 [GEO97] W14 WR* 17 45 39.9190 -29 00 28.592           O8.5/9.5I? 19 0
29 GCIRS 15SW WR* 17 45 39.92 -29 00 18.1           WN8/WC9 38 0
30 [GPE2000] 2.24 * 17 45 39.924 -29 00 29.53           K-M 8 0
31 [GEO97] W4 * 17 45 39.937 -29 00 27.62           K-M 8 0
32 [GEO97] W10 * 17 45 39.9393 -29 00 28.416           O8/9.5I/III 21 0
33 [GEO97] W12 * 17 45 39.954 -29 00 29.08           K-M 10 0
34 [GEO97] W8 * 17 45 39.9563 -29 00 28.112           K-M 10 0
35 GCIRS 29NE1 WR* 17 45 39.9643 -29 00 26.021           WC8/9 34 0
36 [GEO97] W5 * 17 45 39.9696 -29 00 27.843           O9/9.5V 30 0
37 [GEO97] W13 s?b 17 45 39.9799 -29 00 29.103           OBI? 32 0
38 [GEO97] W9 * 17 45 39.9832 -29 00 28.366           O9.5/B2V 21 0
39 GCIRS 7 * 17 45 39.987 -29 00 22.24           M2 361 0
40 [GEO97] W11 * 17 45 39.9935 -29 00 28.975           OB 18 0
41 [GEO97] W6 * 17 45 39.9994 -29 00 27.693           K-M 15 0
42 GCIRS 16 Cl* 17 45 40.0 -29 00 28           ~ 343 0
43 GCIRS 20 * 17 45 40.01 -29 00 33.9           M7III 20 0
44 [EG97] S19 * 17 45 40.0298 -29 00 28.628           K-M 33 0
45 GCIRS 33W * 17 45 40.03 -29 00 31.7           M2III 15 0
46 [EG97] S18 * 17 45 40.0335 -29 00 28.515           ~ 28 0
47 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 4050 3
48 GCIRS 33N s*b 17 45 40.0381 -29 00 30.302           B0.5/1I 38 0
49 [EG97] S1 * 17 45 40.0418 -29 00 28.324           B0/2V 88 0
50 [EG97] S2 * 17 45 40.0442 -29 00 27.975           B0/2V 338 1
51 GCIRS 16NW WR* 17 45 40.0451 -29 00 26.847           Ofpe/WN9 132 0
52 [CRG2004] 12 * 17 45 40.0455 -29 00 28.467           K-M 36 0
53 [EG97] S9 * 17 45 40.0557 -29 00 28.448           B0/2V 46 0
54 [CRG2004] 10 * 17 45 40.0558 -29 00 28.657           O-B 25 0
55 [EG97] S4 * 17 45 40.0636 -29 00 27.968           B0/2V 54 0
56 [EG97] S5 * 17 45 40.0686 -29 00 27.895           B4/9V 29 0
57 GCIRS 14SW * 17 45 40.07 -29 00 37.7           M0III 21 0
58 [EG97] S8 * 17 45 40.0716 -29 00 28.363           B0/2V 71 0
59 [EG97] S6 * 17 45 40.0786 -29 00 27.997           B:V 42 0
60 [EG97] S7 * 17 45 40.0812 -29 00 28.135           B:V 37 0
61 GCIRS 33E WR* 17 45 40.0941 -29 00 31.213           Ofpe/WN9 55 0
62 GCIRS 15N WR* 17 45 40.11 -29 00 16.3           WN9-Ofpe 8 0
63 GCIRS 16C WR* 17 45 40.12 -29 00 27.6           Ofpe/WN9 179 1
64 GCIRS 16SW WR* 17 45 40.1245 -29 00 29.018           Ofpe/WN9 153 0
65 GCIRS 14N * 17 45 40.15 -29 00 36.7           ~ 5 0
66 GCIRS 15NE WR* 17 45 40.15 -29 00 16.5           WN8/9 57 0
67 GCIRS 16SE1 WR* 17 45 40.181 -29 00 29.26           WC8/9 44 0
68 GCIRS 16CC s*b 17 45 40.1939 -29 00 27.532           O9.5/B0.5I 53 0
69 GCIRS 1 * 17 45 40.2 -29 00 27           ~ 66 0
70 GCIRS 21 WR* 17 45 40.222 -29 00 30.85           WC9 99 0
71 [BSD96] 86 * 17 45 40.250 -29 00 30.66           ~ 3 0
72 GCIRS 35W WR* 17 45 40.26 -29 00 29.3           WN5/6 45 0
73 GCIRS 16NE WR* 17 45 40.26 -29 00 27.2           Ofpe/WN9 148 0
74 GCIRS 7SE * 17 45 40.2638 -29 00 24.703           ~ 20 0
75 GCIRS 7E * 17 45 40.38 -29 00 22.9           ~ 9 0
76 BHA 17 * 17 45 40.40 -29 00 39.4           ~ 3 0
77 GCIRS 9 LP* 17 45 40.447 -29 00 34.49           M3III 103 0
78 GCIRS 1NE3 * 17 45 40.53 -29 00 26.9           M0III 4 0
79 GCIRS 1NE2 * 17 45 40.53 -29 00 26.1           M3III 3 0
80 GCIRS 1NE1 * 17 45 40.57 -29 00 26.1           M5III 3 0
81 OH 359.946 -0.047 OH* 17 45 40.63 -29 00 23.5           O-rich 60 0
82 GCIRS 28 * 17 45 40.80 -29 00 33.7           M6III 38 0
83 GCIRS 17 * 17 45 41.0377 -29 00 22.611           ~ 33 0
84 GCIRS 18 * 17 45 41.223 -29 00 38.91           ~ 12 0
85 [GPE2000] 11.38 * ~ ~           ~ 3 0
86 [GPE2000] 14.38 * ~ ~           ~ 3 0
87 GCIRS 1SE1 IR ~ ~           ~ 1 0
88 GCIRS 1S * ~ ~           ~ 2 0
89 GCIRS 13SSE * ~ ~           ~ 3 0
90 [EG97] S3 * ~ ~           ~ 10 0
91 NAME AF NWW * ~ ~           ~ 5 0
92 GCIRS 9S Em* ~ ~           ~ 6 0
93 GCIRS 9NW * ~ ~           ~ 7 0
94 GCIRS 10EW * ~ ~           ~ 2 0
95 [GPE2000] 1.34 * ~ ~           ~ 1 0

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2023.02.06-07:36:36

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