2015A&A...576A..28P


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.17CEST01:15:18

2015A&A...576A..28P - Astronomy and Astrophysics, volume 576A, 28-28 (2015/4-1)

Which young clusters and associations are we missing today?

PFALZNER S., VINCKE K. and XIANG M.

Abstract (from CDS):

Currently clusters and association of stars are mainly detected as surface density enhancements relative to the background field. While clusters form, their surface density increases. It likely decreases again at the end of the star formation process when the system expands as a consequence of gas expulsion. Therefore the surface density of a single cluster can change considerably in young clusters during the first 20Myr of their development. We investigate the effect of the gas expulsion on the detectability of clusters and associations typical of the solar neighbourhood, where the star formation efficiency is <35%. The main focus is on the dependence on the initial cluster mass. N-body methods are used to determine the cluster and association dynamics after gas expulsion. We find that, even for low background densities, only clusters and associations with initial central surface densities exceeding a few 1000M/pc2 will be detected as clusters at ages 5Myr. Even the Orion nebula cluster, one of the most massive nearby clusters, would only be categorised as a small co-moving group with current methods after 5Myr of development. This means that cluster expansion leads to a selection effect - at ages of <1-2Myr the full range of clusters and associations is observed whereas at ages >4Myr only the most massive clusters are identified, while systems with initially Mc<3000M are missing. The temporal development of stellar properties is usually determined by observing clusters of different ages. The potentially strong inhomogeneity of the cluster sample makes this method highly questionable. However, Gaia could provide the means to rectify this situation because it will be able to detect lower mass clusters.

Abstract Copyright:

Journal keyword(s): open clusters and associations: general

CDS comments: Table 2 Upper Cen-Lup2 and I Lac 2 not identified.

Simbad objects: 29

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Number of rows : 29

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9088 1
2 NGC 346 Cl* 00 59 05.090 -72 10 33.24           ~ 441 0
3 IC 1805 OpC 02 32 42 +61 27.0   7.03 6.5     ~ 466 2
4 NGC 1333 SFR 03 28 55 +31 22.2   10.9       ~ 1181 1
5 IC 348 OpC 03 44 34 +32 09.8           ~ 1203 1
6 Ass Ori OB 1b As* 05 34.0 -01 30           ~ 229 0
7 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1906 1
8 Ass Ori OB 1c As* 05 35 21 -05 20.5           ~ 127 1
9 NAME LDN 1641 Center DNe 05 38 46.4 -07 01 05           ~ 51 0
10 NGC 2024 Cl* 05 41 43 -01 50.5           ~ 1056 1
11 M 78 RNe 05 46 45.8 +00 04 45   8.0       ~ 334 0
12 NGC 2071 RNe 05 47 10 +00 18.0           ~ 602 1
13 NAME Mon R2 HII 06 07 46.6 -06 22 59           ~ 633 2
14 NAME GGD 12-15 Cl* 06 10 51.0 -06 11 54           ~ 76 1
15 NGC 2244 OpC 06 31 55 +04 56.5   5.26 4.8     ~ 553 4
16 NGC 2282 RNe 06 46 51 +01 18.9   10       ~ 41 2
17 NGC 3603 HII 11 15 24 -61 15.0           ~ 919 2
18 NAME Lower Centaurus Crux As* 12 19 -57.1           ~ 334 1
19 Cl Trumpler 20 OpC 12 39 45 -60 38.1     10.1     ~ 67 0
20 NGC 4815 OpC 12 58 01 -64 57.6   9.61 8.6     ~ 65 0
21 NAME Upper Centaurus Lupus As* 15 24 -41.9           ~ 342 1
22 NAME Upper Sco Association As* 16 12 -23.4           ~ 959 1
23 NOVA Sco 1863 No* 16 22 30.7782086963 -17 52 43.162570042   8.80 8.70     F8+K2 458 0
24 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 10997 0
25 M 16 OpC 18 18 48 -13 48.4   6.58 6.0     ~ 920 2
26 NGC 6705 OpC 18 51 05 -06 16.2   6.32 5.8     ~ 349 0
27 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 758 0
28 NGC 7380 OpC 22 47 21 +58 07.9   7.62 7.2     ~ 171 0
29 Ass Ori OB 1a As* ~ ~           ~ 185 0

    Equat.    Gal    SGal    Ecl

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2019.10.17-01:15:18

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