2010ApJ...713..871W


C.D.S. - SIMBAD4 rel 1.7 - 2020.05.25CEST01:35:25

2010ApJ...713..871W - Astrophys. J., 713, 871-882 (2010/April-3)

The massive star-forming region Cygnus OB2. II. Integrated stellar properties and the star formation history.

WRIGHT N.J., DRAKE J.J., DREW J.E. and VINK J.S.

Abstract (from CDS):

Cygnus OB2 is the nearest example of a massive star-forming region (SFR), containing over 50 O-type stars and hundreds of B-type stars. We have analyzed the properties of young stars in two fields in Cyg OB2 using the recently published deep catalog of Chandra X-ray point sources with complementary optical and near-IR photometry. Our sample is complete to ∼1 M(excluding A- and B-type stars that do not emit X-rays), making this the deepest study of the stellar properties and star formation history in Cyg OB2 to date. From Siess et al. isochrone fits to the near-IR color-magnitude diagram, we derive ages of 3.5+0.75–1.0 and 5.25+1.5–1.0Myr for sources in the two fields, both with considerable spreads around the pre-main-sequence isochrones. The presence of a stellar population somewhat older than the present-day O-type stars, also fits in with the low fraction of sources with inner circumstellar disks (as traced by the K-band excess) that we find to be very low, but appropriate for a population of age ∼5 Myr. We also find that the region lacks a population of highly embedded sources that is often observed in young SFRs, suggesting star formation in the vicinity has declined. We measure the stellar mass functions (MFs) in this limit and find a power-law slope of Γ = -1.09±0.13, in good agreement with the global mean value estimated by Kroupa. A steepening of the slope at higher masses is observed and suggested as due to the presence of the previous generation of stars that have lost their most massive members. Finally, combining our MF and an estimate of the radial density profile of the association suggests a total mass of Cyg OB2 of ∼3x104 M, similar to that of many of our Galaxy's most massive SFRs.

Abstract Copyright:

Journal keyword(s): open clusters and associations: individual: Cygnus OB2 - stars: early-type - stars: formation - stars: pre-main sequence

VizieR on-line data: <Available at CDS (J/ApJ/713/871): table1.dat>

Status at CDS:   could be processed
// All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 22

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Number of rows : 22

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 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3439 0
2 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14734 1
3 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1960 1
4 M 42 HII 05 35 17.3 -05 23 28           ~ 3709 0
5 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1724 1
6 NAME Car Arm PoG 10 00 -60.0           ~ 376 1
7 Cl Westerlund 2 OpC 10 23 58.1 -57 45 49   11.59 10.5     ~ 273 0
8 NGC 3603 OpC 11 15 18.6 -61 15 26           ~ 933 1
9 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3002 0
10 Cl Westerlund 1 OpC 16 47 04.00 -45 51 04.9           ~ 459 0
11 NGC 6357 HII 17 26.5 -34 12           ~ 249 0
12 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11426 0
13 NAME Arches Cluster Cl* 17 45 50.5 -28 49 28           ~ 626 0
14 NAME Quintuplet Cluster OpC 17 46 13.9 -28 49 48           ~ 439 0
15 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1481 0
16 W 49a SFR 19 10 15.7 +09 06 05           ~ 257 2
17 Ass Cyg OB 9 As* 20 21 +39.9           ~ 116 0
18 NAME Cyg X Cld 20 28 41 +41 10.2           ~ 612 1
19 NAME Cyg Complex reg 20 32 +45.0           ~ 518 0
20 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 781 0
21 [CPR2002] A37 * 20 36 04.4995821629 +40 56 13.037685329           O5V((f)) 18 0
22 NAME III CEP ASSOC As* 23 04.2 +63 24           ~ 294 0

    Equat.    Gal    SGal    Ecl

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2020.05.25-01:35:25

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