2000AJ....120.3139C


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.29CET14:52:52

2000AJ....120.3139C - Astron. J., 120, 3139-3161 (2000/December-0)

2MASS observations of the Perseus, Orion A, Orion B, and Monoceros R2 molecular clouds.

CARPENTER J.M.

Abstract (from CDS):

We use the 2MASS Second Incremental Release Point Source Catalog to investigate the spatial distribution of young stars in the Perseus, Orion A, Orion B, and MonR2 molecular clouds. After subtracting a semiempirical model of the field star contamination from the observed star counts, stellar surface density maps are used to identify compact clusters and any stellar population found more uniformly distributed over the molecular cloud. Each cloud contains between two and seven clusters, with at least half of the cluster population found in a single, rich cluster. In addition, a distributed stellar population is inferred in the Orion A and MonR2 molecular clouds within the uncertainties of the field star subtraction with a surface density between 0.013 and 0.083 arcmin–2. Sensitivity calculations suggest, however, that the number of stars in the distributed population may be underestimated by a factor of 2 or more if stars have been forming with a Miller-Scalo IMF at a constant star formation rate for longer than 10 Myr. After considering the possible evolutionary status of the distributed population, the global star formation efficiency implied by the sum of the distributed and cluster populations ranges between 1% and 9% among the four clouds. The fraction of the total stellar population contained in clusters for the nominal extinction model ranges from ~50% to 100% if the distributed population is relatively young (<10 Myr), to ~25%-70% if it is relatively old (~100 Myr). The relatively high fraction of stars contained in clusters regardless of the age of the distributed population, in conjunction with the young ages generally inferred for embedded clusters in nearby molecular clouds, indicates that a substantial fraction of the total stellar population in these regions has formed within the past few million years in dense clusters. This suggests that either the star formation rate in each these clouds has recently peaked if one assumes clouds have ages greater than 10 Myr or molecular clouds are younger than typically thought if one assumes that the star formation rate has been approximately constant in time.

Abstract Copyright:

Journal keyword(s): ISM: individual (Orion A, Orion B, Monoceros R2, Perseus molecular cloud) - Stars: Formation - Stars: Pre-Main-Sequence

Nomenclature: Table 2: [C2000b] NN (Nos 1-14).

Simbad objects: 55

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Number of rows : 55

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 LDN 1448 DNe 03 22.5 +30 35           ~ 469 0
2 LDN 1455 DNe 03 28 00.6480 +30 07 58.800           ~ 169 1
3 NGC 1333 OpC 03 29 11 +31 18.6           ~ 1231 1
4 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1086 0
5 NAME Per Region reg 03 37 00.0 +31 15 00           ~ 232 0
6 IC 348 OpC 03 44 34 +32 09.8           ~ 1237 1
7 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3546 0
8 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2014 1
9 HH 34 HH 05 35 31.30 -06 28 43.0     16     ~ 469 2
10 NAME LDN 1641 North HII 05 36 17.6 -06 22 10           ~ 216 0
11 BD-06 1253 Ae* 05 36 25.4313245626 -06 42 57.684449700   11.65 10.9 10.29   A1e 408 1
12 [BDB2003] G210.80-19.50 Cl* 05 37 52.9 -06 57 09           ~ 3 0
13 V* V592 Ori Or* 05 37 54.4806159129 -06 57 31.005915144     14.090   12.450 K6.5 23 0
14 Haro 4-438 Em* 05 37 54.5120129582 -06 56 45.497729128   14.80 13.967   11.977 K7 22 0
15 NAME Ori A MoC 05 38 -07.1           ~ 2698 0
16 IRAS 05362-0659 Y*O 05 38 40.48824 -06 58 21.2412           ~ 18 0
17 NAME LDN 1641 Center DNe 05 38 46.4 -07 01 05           ~ 51 0
18 NAME LDN 1641C Cluster Cl* 05 38 49.6 -07 01 32           ~ 4 0
19 LDN 1641 MoC 05 39.0 -07 00           ~ 428 0
20 NAME LDN 1641 South DNe 05 40 27.6 -07 27 28           ~ 47 1
21 NAME Horsehead Nebula DNe 05 40 59.0 -02 27 30           ~ 451 0
22 NGC 2023 RNe 05 41 37.9 -02 15 52           ~ 574 1
23 NAME Ori B MoC 05 41 43.0 -01 54 44           ~ 1182 0
24 NGC 2024 Cl* 05 41 43 -01 50.5           ~ 1077 1
25 2MASS J05422695-0809173 Y*O 05 42 26.9547504449 -08 09 17.260795359     17.208   14.617 M3.5 6 0
26 2MASS J05423489-1001464 Y*O 05 42 34.8876317846 -10 01 46.475685263     14.9     ~ 8 0
27 [BDB2003] G214.27-19.78 Cl* 05 42 38.4 -10 00 51           ~ 2 0
28 Kiso A-1048 60 Y*O 05 42 48.702072 -08 38 31.07832   18.43 16.69 15.88 13.810 K7.5 18 0
29 IRAS 05404-0946 Y*O 05 42 49.39488 -09 45 15.0228           ~ 4 0
30 [BDB2003] G212.98-19.15 Cl* 05 42 50.1 -08 38 37           ~ 4 0
31 [BDB2003] G214.06-19.62 Cl* 05 42 53.5 -09 45 38           ~ 3 0
32 LDN 1630 DNe 05 45.5 -00 59           ~ 352 0
33 M 78 RNe 05 46 45.8 +00 04 45   8.0       ~ 345 0
34 [C2000b] 9 Cl* 05 46 47.0 +00 06 16           ~ 1 0
35 NGC 2071 RNe 05 47 10 +00 18.0           ~ 610 1
36 NAME ORI MOL CLOUD MoC 05 56 -01.8           ~ 866 1
37 [BDB2003] G213.34-12.60 OpC 06 07 08.1 -06 03 53           ~ 6 0
38 IRAS 06046-0603 IR 06 07 08.4 -06 03 47           ~ 13 0
39 NAME Mon R 2 GMC MoC 06 07.6 -06 23           ~ 23 1
40 NAME Mon R2 HII 06 07 46.6 -06 22 59           ~ 655 2
41 NAME Mon R2 Stellar Cluster Cl* 06 07 47.8 -06 22 20           ~ 5 0
42 HD 42050 *iN 06 08 26.2793376496 -05 20 22.476751622 7.39 8.13 8.12     B2III 36 1
43 NGC 2182 RNe 06 09 30.0 -06 19 40   9.0       B3 21 0
44 HD 42261 ** 06 09 31.253880 -06 19 32.80620       9.69   B3/5II/III 25 1
45 NAME GGD 12-15 OpC 06 10 52 -06 12.8           ~ 138 1
46 BD-06 1444 *iN 06 11 48.7972028928 -06 09 27.749129887   11.4 10.9     B4V 11 1
47 NAME GGD 17 IR Cluster Cl* 06 12 48.0 -06 13 56           ~ 2 0
48 GGD 17 HH 06 12.8 -06 13           ~ 21 0
49 IRAS 06124-0621 IR 06 14 52.9 -06 22 43           ~ 5 0
50 IRAS 06128-0624 IR 06 15 19.0 -06 25 13           ~ 2 0
51 NAME Rosette Nebula HII 06 31 40 +04 57.8           ~ 450 1
52 NGC 2264 OpC 06 40 58 +09 53.7     3.9     ~ 1602 1
53 NAME Cha I MoC 11 06 48 -77 18.0           ~ 987 1
54 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3067 0
55 NAME Ori B GMC MoC ~ ~           ~ 14 0

    Equat.    Gal    SGal    Ecl

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2020.10.29-14:52:52

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