2019AJ....158..122K


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.05CET18:43:27

2019AJ....158..122K - Astron. J., 158, 122-122 (2019/September-0)

Untangling the Galaxy. I. Local structure and star formation history of the Milky Way.

KOUNKEL M. and COVEY K.

Abstract (from CDS):

Gaia DR2 provides unprecedented precision in measurements of the distance and kinematics of stars in the solar neighborhood. Through applying unsupervised machine learning on DR2's 5D data set (3D position + 2D velocity), we identify a number of clusters, associations, and comoving groups within 1 kpc and | b| < 30 (many of which have not been previously known). We estimate their ages with the precision of ∼0.15 dex. Many of these groups appear to be filamentary or string-like, oriented in parallel to the Galactic plane, and some span hundreds of parsec in length. Most of these string lack a central cluster, indicating that their filamentary structure is primordial, rather than the result of tidal stripping or dynamical processing. The youngest strings (<100 Myr) are orthogonal to the Local Arm. The older ones appear to be remnants of several other arm-like structures that cannot be presently traced by dust and gas. The velocity dispersion measured from the ensemble of groups and strings increase with age, suggesting a timescale for dynamical heating of ∼300 Myr. This timescale is also consistent with the age at which the population of strings begins to decline, while the population in more compact groups continues to increase, suggesting that dynamical processes are disrupting the weakly bound string populations, leaving only individual clusters to be identified at the oldest ages. These data shed a new light on the local galactic structure and a large-scale cloud collapse.

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): Milky Way dynamics - Galaxy structure - Stellar kinematics - Stellar associations - Star clusters - Stellar ages

VizieR on-line data: <Available at CDS (J/AJ/158/122): table2.dat table3.dat table1.dat>

Nomenclature: Table 2: [KC2019] Theia NNNN (Nos 1-1640).

Status at CDS : Acronym for new objects described in the dictionary of nomenclature and being created in SIMBAD. // All or part of tables of objects will be ingested in SIMBAD with priority 1.

Simbad objects: 19

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Number of rows : 19

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME THA As* 00 00 -62.0           ~ 369 0
2 Cl Melotte 20 OpC 03 26 42 +48 48.0           ~ 769 0
3 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1122 0
4 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 3064 0
5 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2743 0
6 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3650 0
7 M 42 HII 05 35 17.3 -05 23 28           ~ 3777 0
8 NAME Ori Complex Cld 05 35.3 -05 23           ~ 357 0
9 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1509 0
10 NGC 2232 OpC 06 27 15 -04 45.5           ~ 137 0
11 NAME TW Hya Association As* 11 01.9 -34 42           ~ 840 0
12 NAME Lower Centaurus Crux As* 12 19 -57.1           ~ 372 1
13 NAME Ursa Major Moving Group MGr 12 32 +57.0           ~ 390 2
14 NAME Upper Sco Association As* 16 12 -23.4           ~ 1086 1
15 NAME ASSOC II SCO As* 16 15 -24.2           ~ 1160 1
16 NAME CrA Complex reg 19 15 00.0 -37 30 00           ~ 102 1
17 NAME AB Dor Moving Group MGr ~ ~           ~ 382 0
18 NAME Local Arm reg ~ ~           ~ 395 0
19 NAME Gould Belt PoG ~ ~           ~ 749 1

    Equat.    Gal    SGal    Ecl

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2021.03.05-18:43:27

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