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Query : 2000ApJ...540..255P |
2000ApJ...540..255P - Astrophys. J., 540, 255-270 (2000/September-1)
Accelerating star formation in clusters and associations.
PALLA F. and STAHLER S.W.
Abstract (from CDS):
Our investigation corroborates and extends our previous results on the Orion Nebula Cluster. In all cases, we find that star formation began at a relatively low level some 107 yr in the past and has more recently undergone a steep acceleration. This acceleration, which lasts several million years, is usually continuing through the present epoch. The one clear exception is the OB association Upper Scorpius, where the formation rate climbed upward, peaked, and has now died off. Significantly, this is also the only region of our list that has been largely stripped of molecular gas.
The acceleration represents a true physical phenomenon that cannot be explained away by incompleteness of the samples; nor is the pattern of stellar births significantly affected by observational errors or the presence of unresolved binaries. We speculate that increasing star formation activity arises from contraction of the parent cloud. Despite the short timescale for acceleration, the cloud is likely to evolve quasi-statically. Star formation itself appears to be a critical phenomenon, occurring only in locations exceeding some threshold density. The cloud's contraction must reverse itself, and the remnant gas dissipate, in less than 107 yr, even for aggregates containing no massive stars. In this case, molecular outflows from the stars themselves presumably accomplish the task, but the actual dispersal mechanism is still unclear.
Abstract Copyright: ∼
Journal keyword(s): open clusters and associations: individual (Chamaeleon, IC 348, Lupus, NGC 2264, Orion Nebula Cluster, ρ Ophiuchi, Taurus-Auriga, Upper Scorpius) - Stars: Evolution - Stars: Formation - Stars: Pre-Main-Sequence
CDS comments: p. 264, 265 : W178 = NGC 2264 178
Simbad objects: 44
Number of rows : 44 |
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 1333 | OpC | 03 29 11.3 | +31 18 36 | ~ | 1454 | 1 | |||||
2 | NAME Perseus Cloud | SFR | 03 35.0 | +31 13 | ~ | 1371 | 0 | |||||
3 | Ass Per OB 2 | As* | 03 42.2 | +33 26 | ~ | 339 | 0 | |||||
4 | IC 348 | OpC | 03 44 31.7 | +32 09 32 | ~ | 1395 | 1 | |||||
5 | HD 281159 | Y*O | 03 44 34.1873929 | +32 09 46.137563 | 9.19 | 9.21 | 8.53 | 8.85 | 7.850 | B5V | 224 | 0 |
6 | LDN 1495E | Cl* | 04 13 30.7 | +28 19 15 | ~ | 33 | 0 | |||||
7 | IRAS 04191+1523 | Y*O | 04 22 00.43944 | +15 30 21.2148 | ~ | 199 | 0 | |||||
8 | NAME Tau-Aur Complex | SFR | 04 30 | +25.0 | ~ | 1359 | 0 | |||||
9 | LDN 1527 | DNe | 04 39 53 | +25 45.0 | ~ | 636 | 0 | |||||
10 | NAME Orion Nebula Cluster | OpC | 05 35.0 | -05 29 | ~ | 2334 | 0 | |||||
11 | NAME Ori Trapezium | OpC | 05 35 16.5 | -05 23 14 | ~ | 1621 | 1 | |||||
12 | M 42 | HII | 05 35 17 | -05 23.4 | ~ | 4083 | 0 | |||||
13 | NAME Ori A | MoC | 05 38 | -07.1 | ~ | 3017 | 0 | |||||
14 | NAME Orion Molecular Cloud | MoC | 05 56 | -01.8 | ~ | 1101 | 1 | |||||
15 | NGC 2264 | OpC | 06 40 52.1 | +09 52 37 | ~ | 1793 | 0 | |||||
16 | * 15 Mon | Be* | 06 40 58.65963 | +09 53 44.7229 | 3.360 | 4.45 | 4.68 | 4.88 | O7V+B1.5/2V | 803 | 0 | |
17 | NAME Cone Nebula | DNe | 06 41.1 | +09 53 | ~ | 86 | 1 | |||||
18 | HD 47887 | Y*O | 06 41 09.5990050152 | +09 27 57.538520712 | 6.01 | 6.96 | 7.14 | 7.40 | B0.7V | 104 | 0 | |
19 | NAME Cha 1 | MoC | 11 06 48 | -77 18.0 | ~ | 1154 | 1 | |||||
20 | NAME Cha T Association | As* | 11 10 16.7 | -76 42 03 | ~ | 42 | 1 | |||||
21 | NAME Lower Centaurus Crux | As* | 12 19 | -57.1 | ~ | 479 | 1 | |||||
22 | IRAS 12340-7958 | LP* | 12 37 39.7408011816 | -80 15 13.707391932 | 16.11 | 14.39 | 13.63 | 9.81 | ~ | 107 | 0 | |
23 | NAME Cha III | MoC | 12 37.8 | -80 15 | ~ | 140 | 2 | |||||
24 | V* DK Cha | TT* | 12 53 17.2111480272 | -77 07 10.736046012 | F0e | 142 | 0 | |||||
25 | NAME Cha II | MoC | 12 54 | -77.2 | ~ | 337 | 0 | |||||
26 | NAME Upper Centaurus Lupus | As* | 15 24 | -41.9 | ~ | 476 | 1 | |||||
27 | Lupus 1 | Cld | 15 43 02.1 | -34 09 06 | ~ | 286 | 0 | |||||
28 | Lupus 2 | MoC | 15 57 08 | -37 47.1 | ~ | 114 | 1 | |||||
29 | NAME Lupus Complex | SFR | 16 03 | -38.1 | ~ | 720 | 0 | |||||
30 | Lupus 4 | MoC | 16 03 12.4 | -42 07 43 | ~ | 152 | 0 | |||||
31 | Lupus 3 | SFR | 16 09.6 | -39 03 | ~ | 323 | 0 | |||||
32 | NAME Upper Sco Association | As* | 16 12 | -23.4 | ~ | 1369 | 1 | |||||
33 | NAME Upper Sco-Cen | As* | 16 15 | -24.2 | ~ | 1332 | 1 | |||||
34 | NAME rho Oph Complex | reg | 16 25 | -23.5 | ~ | 79 | 1 | |||||
35 | * rho Oph | ** | 16 25 35.11766 | -23 26 49.8150 | 4.30 | 4.85 | 4.63 | 4.27 | 3.96 | B2IV+B2V | 648 | 0 |
36 | NAME rho Oph A Cloud | MoC | 16 26 26.4 | -24 22 33 | ~ | 291 | 1 | |||||
37 | NAME rho Oph C Cloud | MoC | 16 26 53.1 | -24 32 31 | ~ | 77 | 0 | |||||
38 | * chi Oph | Be* | 16 27 01.4355697915 | -18 27 22.499961252 | 3.95 | 4.71 | 4.43 | 3.97 | 3.73 | B2Vne | 598 | 0 |
39 | NAME rho Oph E | MoC | 16 27 02.0 | -24 38 31 | ~ | 63 | 0 | |||||
40 | NAME rho Oph B Cloud | MoC | 16 27 11 | -24 28.5 | ~ | 84 | 1 | |||||
41 | NAME rho Oph F | MoC | 16 27 37.3 | -24 42 28 | ~ | 63 | 0 | |||||
42 | NAME Ophiuchus Molecular Cloud | SFR | 16 28 06 | -24 32.5 | ~ | 3636 | 1 | |||||
43 | NAME Ophiuchus D | MoC | 16 28 29.2 | -24 18 25 | ~ | 117 | 0 | |||||
44 | LDN 1689 | DNe | 16 32 22.5 | -24 28 29 | ~ | 138 | 0 |
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