2018PASP..130g2001G


Query : 2018PASP..130g2001G

2018PASP..130g2001G - Publ. Astron. Soc. Pac., 130, part no 7, 2001-72001 (2018/July-0)

Unbound young stellar systems: star formation on the loose.

GOULIERMIS D.A.

Abstract (from CDS):

Unbound young stellar systems, the loose ensembles of physically related young bright stars, trace the typical regions of recent star formation in galaxies. Their morphologies vary from small few pc-size associations of newly formed stars to enormous few kpc-size complexes composed of stars few 100 Myr old. These stellar conglomerations are located within the disks and along the spiral arms and rings of star-forming disk galaxies, and they are the active star-forming centers of dwarf and starburst galaxies. Being associated with star-forming regions of various sizes, these stellar structures trace the regions where stars form at various length- and timescales, from compact clusters to whole galactic disks. Stellar associations, the prototypical unbound young systems, and their larger counterparts, stellar aggregates, and stellar complexes, have been the focus of several studies for quite a few decades, with special interest on their demographics, classification, and structural morphology. The compiled surveys of these loose young stellar systems demonstrate that the clear distinction of these systems into well-defined classes is not as straightforward as for stellar clusters, due to their low densities, asymmetric shapes and variety in structural parameters. These surveys also illustrate that unbound stellar structures follow a clear hierarchical pattern in the clustering of their stars across various scales. Stellar associations are characterized by significant sub-structure with bound stellar clusters being their most compact parts, while associations themselves are the brighter denser parts of larger stellar aggregates and stellar complexes, which are members of larger super-structures up to the scale of a whole star-forming galaxy. This structural pattern, which is usually characterized as self-similar or fractal, appears to be identical to that of star-forming giant molecular clouds and interstellar gas, driven mainly by turbulence cascade. In this short review, I make a concise compilation of our understanding of unbound young stellar systems across various environments in the local universe, as it is developed during the last 60 years. I present a factual assessment of the clustering behavior of star formation, as revealed from the assembling pattern of stars across loose stellar structures and its relation to the interstellar medium and the environmental conditions. I also provide a consistent account of the processes that possibly play important role in the formation of unbound stellar systems, compiled from both theoretical and observational investigations on the field.

Abstract Copyright: © 2018. The Astronomical Society of the Pacific.

Journal keyword(s):

Simbad objects: 48

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Number of rows : 48
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11895 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10322 1
3 NGC 346 Cl* 00 59 05.090 -72 10 33.24           ~ 462 0
4 IC 1613 GiC 01 04 54.2 +02 08 00   10.42 10.01 9.77   ~ 1172 2
5 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 5529 1
6 W 3 MoC 02 27 04.10 +61 52 27.1           ~ 1003 3
7 NGC 925 H2G 02 27 16.913 +33 34 43.97   10.69 10.12 9.55   ~ 735 1
8 NAME Heart Nebula HII 02 32.7 +61 27           ~ 304 1
9 Ass Cas OB 6 As* 02 43 +61.3           ~ 121 0
10 IC 1848 OpC 02 51 25 +60 25.1   6.87 6.5     ~ 468 2
11 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6377 1
12 NGC 1313 G 03 18 16.046 -66 29 53.74   10.06 10.0 9.40 10.4 ~ 652 2
13 NGC 1566 Sy1 04 20 00.3968473248 -54 56 16.624708764 10.29 10.19 9.73 9.21 10.1 ~ 809 2
14 NGC 1935 As* 05 21 58 -67 57.3           ~ 106 0
15 LHA 120-N 44 EmO 05 22 06.9 -67 56 46           ~ 185 1
16 NGC 1937 As* 05 22 29 -67 53.7           ~ 44 1
17 LH 49 As* 05 22 55 -68 03.6           ~ 31 1
18 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16168 1
19 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2161 1
20 SMP LMC 83 PN 05 36 20.7215081304 -67 18 07.658262756 15.56 16.225 14.948   16.558 [WN4.5:] 143 0
21 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1873 1
22 NAME Orion Molecular Cloud MoC 05 56 -01.8           ~ 1001 1
23 NGC 2366 H2G 07 28 51.85 +69 12 31.1 12.25 11.86 11.39 11.33   ~ 732 0
24 NGC 2403 AGN 07 36 51.3381434280 +65 36 09.650825640 9.31 8.84 8.38 8.19   ~ 1701 1
25 Ass Vel OB 2 As* 08 09 22.478 -47 21 03.46           ~ 245 0
26 * gam02 Vel WR* 08 09 31.95013 -47 20 11.7108 0.64 1.58 1.83 1.85 2.00 WC8+O7.5III-V 870 0
27 NGC 2547 OpC 08 09 52.360 -49 10 35.01           ~ 362 0
28 NGC 2541 GiG 08 14 40.1160678912 +49 03 42.021679932 12.03 12.26 11.80     ~ 293 1
29 UGC 5336 G 09 57 32.1 +69 02 46 15.19 15.15 14.10 14.12   ~ 302 4
30 NAME Sex A H2G 10 11 00.5 -04 41 30 12.48 12.13 11.93 11.78   ~ 692 2
31 IC 2574 G 10 28 23.6148831408 +68 24 43.440012756 11.70 11.07 10.87 10.74   ~ 634 1
32 M 95 GiP 10 43 57.7313485800 +11 42 13.301191332 10.71 10.51 9.73 9.48   ~ 1032 2
33 NGC 3372 HII 10 45 02.23 -59 41 59.8           ~ 953 2
34 NGC 3621 AGN 11 18 16.300 -32 48 45.36 10.10 9.44 9.56 8.07 10.1 ~ 537 3
35 NAME Antennae IG 12 01 53.170 -18 52 37.92           ~ 1632 0
36 M 61 Sy2 12 21 54.9282582888 +04 28 25.597367184 10.07 10.18 9.65     ~ 940 2
37 M 91 LIN 12 35 26.4446761320 +14 29 46.760333748   14.63 13.57     ~ 561 0
38 UGC 8091 H2G 12 58 40.1930636208 +14 13 00.739589628 15.24 15.16 14.98 14.81   ~ 451 0
39 M 51 GiP 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 4099 4
40 M 83 SBG 13 37 00.91920 -29 51 56.7400 8.85 8.11 7.52 7.21   ~ 2411 2
41 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2729 2
42 NGC 6503 LIN 17 49 26.4207792072 +70 08 39.604132176 11.56 10.95 10.28 9.92   ~ 494 1
43 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1501 0
44 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 878 0
45 NGC 7331 LIN 22 37 04.0506038088 +34 24 56.800076508 10.65 10.35 9.48     ~ 1174 2
46 NAME PegDIG G 23 28 35.2 +14 44 35 13.85 13.16 12.52     ~ 449 1
47 NAME Gould Belt PoG ~ ~           ~ 806 1
48 NAME Local Group GrG ~ ~           ~ 7726 0

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2022.08.18-03:48:17

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