2021MNRAS.505.2412C


Query : 2021MNRAS.505.2412C

2021MNRAS.505.2412C - Mon. Not. R. Astron. Soc., 505, 2412-2426 (2021/August-1)

Tree-ring structure of Galactic bar resonance.

CHIBA R. and SCHONRICH R.

Abstract (from CDS):

Galaxy models have long predicted that galactic bars slow down by losing angular momentum to their postulated dark haloes. When the bar slows down, resonance sweeps radially outwards through the galactic disc while growing in volume, thereby sequentially capturing new stars at its surface/separatrix. Since trapped stars conserve their action of libration, which measures the relative distance to the resonance centre, the order of capturing is preserved: the surface of the resonance is dominated by stars captured recently at large radius, while the core of the resonance is occupied by stars trapped early at small radius. The slow down of the bar thus results in a rising mean metallicity of trapped stars from the surface towards the centre of the resonance as the Galaxy's metallicity declines towards large radii. This argument, when applied to Solar neighbourhood stars, allows a novel precision measurement of the bar's current pattern speed Ω_ p_= 35.5 ±0.8 km s–1 kpc–1, placing the corotation radius at R_ CR_= 6.6 ±0.2 kpc. With this pattern speed, the corotation resonance precisely fits the Hercules stream in agreement with kinematics. Beyond corroborating the slow bar theory, this measurement manifests the deceleration of the bar of more than 24 per cent since its formation and thus the angular momentum transfer to the dark halo by dynamical friction. The measurement therefore supports the existence of a standard dark-matter halo rather than alternative models of gravity.

Abstract Copyright: © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society

Journal keyword(s): Galaxy: fundamental parameters - Galaxy: evolution - Galaxy: kinematics and dynamics

Simbad objects: 27

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Number of rows : 27
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 NGC 188 OpC 00 47 11.5 +85 14 38           ~ 922 0
2 NGC 1193 OpC 03 05 56.6 +44 22 59     12.6     ~ 88 0
3 Cl Melotte 20 OpC 03 26 28.1 +48 58 30           ~ 861 0
4 M 37 OpC 05 52 17.8 +32 32 42   6.19 5.6     ~ 402 2
5 NGC 2168 OpC 06 09 05.3 +24 20 10           ~ 559 0
6 Cl Trumpler 5 OpC 06 36 30.2 +09 27 54           ~ 122 0
7 NGC 2266 OpC 06 43 19.7 +26 58 34     9.5     ~ 76 0
8 NGC 2324 OpC 07 04 07.9 +01 02 46   8.83 8.4     ~ 159 0
9 NGC 2335 OpC 07 06 46 -10 01.4   7.76 7.2     ~ 83 0
10 NGC 2355 OpC 07 16 59.3 +13 46 19     9.7     ~ 107 0
11 NGC 2360 OpC 07 17 46.3 -15 37 52           ~ 194 0
12 Cl Melotte 66 OpC 07 26 17.5 -47 41 06   8.73       ~ 196 0
13 NGC 2422 OpC 07 36 35.3 -14 29 20           ~ 246 0
14 Cl Melotte 71 OpC 07 37 31.9 -12 03 54   7.44 7.1     ~ 131 0
15 NGC 2437 OpC 07 41 46.8 -14 50 38           ~ 156 0
16 NGC 2447 OpC 07 44 33.8 -23 51 11           ~ 149 1
17 NGC 2527 OpC 08 04 59.0 -28 07 19   6.81 6.5     ~ 104 0
18 NGC 2547 OpC 08 09 52.360 -49 10 35.01           ~ 400 0
19 NGC 2548 OpC 08 13 38.9 -05 43 34           ~ 182 0
20 NGC 2632 OpC 08 40 13.0 +19 37 16           ~ 1567 0
21 NGC 2682 OpC 08 51 23.0 +11 48 50           ~ 2342 0
22 M 66 GiP 11 20 15.0 +12 59 29 9.85 9.65 8.92     ~ 1387 4
23 IC 4651 OpC 17 24 50.9 -49 55 01           ~ 350 0
24 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 14463 0
25 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 4400 3
26 NAME Galactic Bar reg ~ ~           ~ 1224 0
27 NAME Hercules Stream MGr ~ ~           ~ 237 0

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