J/A+A/525/A1 JHK photometry of CBJC 8 sources (Persi+, 2011)
The distant young embedded stellar cluster CBJC 8 associated with G085.40-0.00.
Persi P., Tapia M., Gomez M.
<Astron. Astrophys. 525, A1 (2011)>
=2011A&A...525A...1P 2011A&A...525A...1P
ADC_Keywords: Associations, stellar ; H II regions ; Photometry, infrared ;
Photometry, millimetric/submm
Keywords: stars: formation - HII regions - ISM: clouds - masers -
stars: protostars - ISM: jets and outflows
Abstract:
The infrared cluster CBJC 8 is associated with a 6.7GHz methanol
maser and a compact radio-continuum source, G85.40-0.00. It is located
at a distance of about 8kpc. The aim is to study the characteristics
of this distant and compact embedded cluster and derive the properties
of its stellar population. We present new ground-based near- and
mid-imaging observations of this region. The calibrated images were
analysed together with archive Spitzer IRAC images. Based on the
discovery of a considerable fraction of embedded sources with infrared
excess emission that are concentrated within a radius around 16arcsec
centred near the position of the compact HII region G85.40-0.00, we
were able to confirm the presence of a very young embedded cluster. It
was found to contain more than 58 members brighter than MK=2.6, with
two-thirds of them showing significant near- or mid-IR excess
emission. Spectral energy distributions and extrapolated total
luminosities are presented for nine sources with large mid-infrared
excesses that were measured in all four IRAC bands. For the brightest
of these, G8540A, which is associated with a methanol maser and a
compact HII region, we fitted a model of an infalling envelope plus
disc plus central star to its observed 1.6 to 850um fluxes to get an
idea of its physical properties. We also report the presence of a
single 2.12um molecular hydrogen line emission knot near the centre of
the cluster, suggesting the outflow activity.
Description:
Coordinates (J2000) and JHK photometry are given for the 493 sources
detected with PANIC on Baade Telescope in an area of 111"x111"
centred on G85.40+0.00 as well as photometry in the four IRAC bands
measured on archive frames of the same area.
Objects:
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RA (2000) DE Designation(s)
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20 54 14.3 +44 54 05 CBJC 8 = [CBJ2002] 8 = [BDB2003] G085.41+00.00
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
jhk.dat 60 393 Coordinates and JHK photometry of all sources
irac.dat 72 32 Coordinates and IRAC photometry of all sources
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Byte-by-byte Description of file: jhk.dat
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Bytes Format Units Label Explanations
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2- 3 I2 h RAh Right ascension (J2000.0)
5- 6 I2 min RAm Right ascension (J2000.0)
8- 12 F5.2 s RAs Right ascension (J2000.0)
14 A1 --- DE- Declination sign (J2000.0)
15- 16 I2 deg DEd Declination (J2000.0)
18- 19 I2 arcmin DEm Declination (J2000.0)
21- 24 F4.1 arcsec DEs Declination (J2000.0)
27- 31 F5.2 mag Jmag ? 2MASS J magnitude
33- 36 F4.2 mag e_Jmag ? Error in J magnitude
39- 43 F5.2 mag Hmag ? 2MASS H magnitude
45- 48 F4.2 mag e_Hmag ? Error in H magnitude
51- 55 F5.2 mag Kmag 2MASS K magnitude
57- 60 F4.2 mag e_Kmag Error in K magnitude
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Byte-by-byte Description of file: irac.dat
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Bytes Format Units Label Explanations
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2- 3 I2 h RAh Right ascension (J2000.0)
5- 6 I2 min RAm Right ascension (J2000.0)
8- 12 F5.2 s RAs Right ascension (J2000.0)
14 A1 --- DE- Declination sign (J2000.0)
15- 16 I2 deg DEd Declination (J2000.0)
18- 19 I2 arcmin DEm Declination (J2000.0)
21- 24 F4.1 arcsec DEs Declination (J2000.0)
27- 31 F5.2 mag [3.6] ? Spitzer/IRAC 3.6um magnitude
33- 36 F4.2 mag e_[3.6] ? Error in [3.6] magnitude
39- 43 F5.2 mag [4.5] ? Spitzer/IRAC 4.5um magnitude
45- 48 F4.2 mag e_[4.5] ? Error in [4.5] magnitude
51- 55 F5.2 mag [5.8] ? Spitzer/IRAC 5.8um magnitude
57- 60 F4.2 mag e_[5.8] ? Error in [5.8] magnitude
63- 67 F5.2 mag [8.0] ? Spitzer/IRAC 8um magnitude
69- 72 F4.2 mag e_[8.0] ? Error in [8] magnitude
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Acknowledgements:
Paolo Persi, paolo.persi(at)iasf-roma.inaf.it
(End) Patricia Vannier [CDS] 25-Nov-2010