J/MNRAS/458/3027 Young and embedded clusters in Cygnus-X (Maia+, 2016)
Young and embedded clusters in Cygnus-X: evidence for building up the initial
mass function?
Maia F.F.S., Moraux E., Joncour I.
<Mon. Not. R. Astron. Soc. 458, 3027 (2016)>
=2016MNRAS.458.3027M 2016MNRAS.458.3027M (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Photometry, infrared
Keywords: stars: low mass - stars: luminosity function, mass function -
stars: pre-main-sequence -
open clusters and associations: Cygnus-X - infrared: stars
Abstract:
We provide a new view on the Cygnus-X north complex by accessing for
the first time the low mass content of young stellar populations in
the region. CFHT/WIRCam camera was used to perform a deep near-IR
survey of this complex, sampling stellar masses down to ∼0.1M☉.
Several analysis tools, including a extinction treatment developed in
this work, were employed to identify and uniformly characterise a
dozen unstudied young star clusters in the area. Investigation of
their mass distributions in low-mass domain revealed a relatively
uniform log-normal IMF with a characteristic mass of
0.32±0.08M☉ and mass dispersion of 0.40±0.06. In the high
mass regime, their derived slopes showed that while the youngest
clusters (age<4Myr) presented slightly shallower values with respect
to the Salpeter's, our older clusters (4Myr<age<18Myr) showed IMF
compliant values and a slightly denser stellar population. Although
possibly evidencing a deviation from an 'universal' IMF, these results
also supports a scenario where these gas dominated young clusters
gradually 'build up' their IMF by accreting low-mass stars formed in
their vicinity during their first ∼3Myr, before the gas expulsion
phase, emerging at the age of ∼4Myr with a fully fledged IMF. Finally,
the derived distances to these clusters confirmed the existence of at
least 3 different star forming regions throughout Cygnus-X north
complex, at distances of 500-900pc, 1.4-1.7kpc and 3.0kpc, and
revealed evidence of a possible interaction between some of these
stellar populations and the Cygnus-OB2 association.
Description:
CFHT/WIRCam was used to acquire deep (960s, 1200s, 480s) JHK exposures
of five fields covering ∼1 degree squared in the Cygnus-X complex, in
six nights between 04/09/2012 and 29/10/2012. The frames were
detrended and coadded into a master mosaic where PSF photometry was
carried out using SExtractor and PSFex software using a 2-sigma
detection threshold. The resulting catalog was calibrated against the
2MASS catalog, but no transformation was done to our data. Instead,
bright sources (brighter than the saturation magnitude) were recovered
from 2MASS and calibrated to the WIRCam instrumental system to
complement our catalog. The final table contains about 310000 stars
spanning 12 magnitudes and reaching K=18.5 at 95% completeness. The
fundamental parameters of 10 young stellar systems in the region were
derived through this final catalogue.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
cluster.dat 129 10 Embedded clusters fundamental parameters
table.dat 78 310625 Coordinates, photometry and membership of
detected stars in Cygnus-X north
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See also:
J/A+A/476/1243 : Millimeter continuum mapping of Cygnus X (Motte+, 2007)
J/ApJ/727/114 : BLAST 2005: a 10deg2 survey in Cygnus X (Roy+, 2011)
J/ApJ/720/679 : Optical spectroscopy in Cygnus X region (Beerer+, 2010)
J/AJ/148/11 : Infrared photometry in Cygnus-X (Kryukova+, 2014)
Byte-by-byte Description of file: cluster.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name Cluster identification (1)
9- 10 I2 h RAh Right ascension (J2000.0)
12- 13 I2 min RAm Right ascension (J2000.0)
15- 16 I2 s RAs Right ascension (J2000.0)
18 A1 --- DE- Declination sign (J2000.0)
19- 20 I2 deg DEd Declination (J2000.0)
22- 23 I2 arcmin DEm Declination (J2000.0)
25- 26 I2 arcsec DEs Declination (J2000.0)
29- 31 I3 pc-2 p Stelar density
33- 35 I3 pc-2 e_p Stelar density uncertainty
38- 41 F4.2 pc rc Core radius
43- 46 F4.2 pc e_rc Core radius uncertainty
49- 52 F4.2 pc rt Tidal radius
54- 57 F4.2 pc e_rt Tidal radius uncertainty
59- 61 I3 Myr Agemin Minimum age
63- 65 I3 Myr Agemax Maximum age
67- 71 F5.2 mag AV Extinction
73- 76 F4.2 mag e_AV Extinction uncertainty
79- 82 F4.2 kpc Distmin Minimum distance
84- 87 F4.2 kpc Distmax Maximum distance
89- 92 I4 Msun Massmin Minimum mass
94- 97 I4 Msun Massmax Maximum mass
99-102 F4.2 Msun Massc ? MF characteristic mass
104-107 F4.2 Msun e_Massc ? MF characteristic mass uncertainty
110-113 F4.2 --- Masss ? MF mass dispersion
115-118 F4.2 --- e_Masss ? MF mass dispersion uncertainty
121-124 F4.2 --- a ? MF slope
126-129 F4.2 --- e_a ? MF slope uncertainty
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Note (1): Cluster identifications are from Le Duigou & Knodlseder
(2002A&A...392..869L 2002A&A...392..869L), Froebrich et al. (2007MNRAS.374..399F 2007MNRAS.374..399F),
Bica et al. (2003A&A...397..177B 2003A&A...397..177B) and Bica et al. (2003A&A...405..991B 2003A&A...405..991B).
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Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 11 F11.7 deg RAdeg Right ascension (J2000)
14- 23 F10.7 deg DEdeg Declination (J2000)
26- 32 F7.4 mag Jmag ? J-band magnitude
35- 40 F6.4 mag e_Jmag ? J-band magnitude uncertainty
43- 49 F7.4 mag Hmag ? H-band magnitude
52- 57 F6.4 mag e_Hmag ? H-band magnitude uncertainty
60- 66 F7.4 mag Kmag ? K-band magnitude
69- 74 F6.4 mag e_Kmag ? K-band magnitude uncertainty
77- 78 I2 --- Memb [0/12] Membership (1)
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Note (1): Cluster membership is indicated by the following 2-digit code:
0 = does not belong to any cluster (field)
1 = member of LK12 cluster
2 = member of LK14 cluster
3 = member of FSR249 cluster
4 = member of LK13 cluster
5 = member of BDB59 cluster
6 = member of BDB58 cluster
7 = member of BDB57 cluster
8 = member of Bica3 cluster
9 = member of LK15 cluster
10 = member of BDB56 cluster
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Acknowledgements:
Francisco Maia, ffsmaia(at)ufmg.br
(End) Francisco Maia [Univ. Joseph Fourier], Patricia Vannier [CDS] 19-Feb-2016