J/MNRAS/439/3719 Embedded clusters infrared photometry (Chavarria+, 2014)
A multiwavelength study of embedded clusters in W5-east, NGC 7538, S235, S252
and S254-S258.
Chavarria L., Allen L., Brunt C., Hora J.L., Muench A., Fazio G.
<Mon. Not. R. Astron. Soc., 439, 3719-3754 (2014)>
=2014MNRAS.439.3719C 2014MNRAS.439.3719C (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; YSOs ; Photometry, infrared
Keywords: stars: early-type - stars: formation - stars: pre-main sequence -
H II regions - infrared: stars
Abstract:
We present Spitzer, near-IR (NIR) and millimetre observations of the
massive star-forming regions W5-east, S235, S252, S254-S258 and
NGC 7538. Spitzer data is combined with NIR observations to identify
and classify the young population while 12CO and 13CO observations
are used to examine the parental molecular cloud. We detect in total
3021 young stellar objects (YSOs). Of those, 539 are classified as
Class I, and 1186 as Class II sources. YSOs are distributed in groups
surrounded by a more scattered population. Class I sources are more
hierarchically organized than Class II and associated with the most
dense molecular material. We identify in total 41 embedded clusters
containing between 52 and 73 per cent of the YSOs. Clusters are in
general non-virialized, turbulent and have star formation efficiencies
between 5 and 50 per cent. We compare the physical properties of
embedded clusters harbouring massive stars (MEC) and low-mass embedded
clusters (LEC) and find that both groups follow similar correlations
where the MEC are an extrapolation of the LEC. The mean separation
between MEC members is smaller compared to the cluster Jeans length
than for LEC members. These results are in agreement with a scenario
where stars are formed in hierarchically distributed dusty filaments
where fragmentation is mainly driven by turbulence for the more
massive clusters. We find several young OB-type stars having IR-excess
emission which may be due to the presence of an accretion disc.
Description:
We present Spitzer, near-IR (NIR) and millimetre observations of the
massive star-forming regions W5-east, S235, S252, S254-S258 and
NGC 7538.
All regions were observed with the Infrared Array Camera (IRAC) on the
Spitzer Space Telescope between 2004 December and 2007 October.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 174 3021 Identified YSOs per region
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/3021] Sequential number
6- 13 A8 --- Region Region name
14- 23 F10.6 deg RAdeg Right ascension (J2000)
25- 33 F9.6 deg DEdeg Declination (J2000)
35- 40 F6.3 mag Jmag ?=- J-band magnitude
44- 48 F5.3 mag e_Jmag ?=- rms uncertainty on Jmag
53- 58 F6.3 mag Hmag ?=- H-band magnitude
62- 66 F5.3 mag e_Hmag ?=- rms uncertainty on Hmag
71- 76 F6.3 mag Kmag ?=- K-band magnitude
79- 84 F6.3 mag e_Kmag ?=- rms uncertainty on Kmag
89- 94 F6.3 mag IRAC1 ?=- IRAC ch1 (3.4um) magnitude
97-102 F6.3 mag e_IRAC1 ?=- rms uncertainty on IRAC1
107-112 F6.3 mag IRAC2 ?=- IRAC ch2 (4.5um) magnitude
115-120 F6.3 mag e_IRAC2 ?=- rms uncertainty on IRAC2
125-130 F6.3 mag IRAC3 ?=- IRAC ch3 (5.8um) magnitude
133-138 F6.3 mag e_IRAC3 ?=- rms uncertainty on IRAC3
143-148 F6.3 mag IRAC4 ?=- IRAC ch4 (8.0um) magnitude
151-156 F6.3 mag e_IRAC4 ?=- rms uncertainty on IRAC4
161-163 F3.1 --- Class [1/2]?=- YSO class (1.0 or 2.0) (1)
165-169 F5.2 --- alpha ?=- YSO IRAC alpha index
171-174 A4 --- Schema YSO classification scheme used
(IRAC, HK2, NIR or MIPS)
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Note (1): Sources with detections in all IRAC bands are classified using their
observed IRAC spectral energy distribution slope αIRAC as follows:
1.0 = Class I (αIRAC>0),
2.0 = Class II (-2<αIRAC<0)
3.0 = stellar photospheres or Class III (αIRAC< -2)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Oct-2018