J/A+A/599/A37 YSO candidates in IRAS 20319+3958 (Djupvik+, 2017)
Globules and pillars in Cygnus X.
II. Massive star formation in the globule IRAS 20319+3958.
Djupvik A.A., Comeron F., Schneider N.
<Astron. Astrophys. 599, A37 (2017)>
=2017A&A...599A..37D 2017A&A...599A..37D (SIMBAD/NED BibCode)
ADC_Keywords: Infrared sources ; Globules ; YSOs ; Photometry, VRI ;
Photometry, infrared ; Photometry, millimetric/submm
Keywords: ISM: clouds - stars: formation -
ISM: individual objects: IRAS 20319+3958 -
ISM: individual objects: Cygnus X
Abstract:
Globules and pillars, impressively revealed by the Spitzer and
Herschel satellites, for example, are pervasive features found in
regions of massive star formation. Studying their embedded stellar
populations can provide an excellent laboratory to test theories of
triggered star formation and the features that it may imprint on the
stellar aggregates resulting from it. We studied the globule
IRAS 20319+3958 in Cygnus X by means of visible and near-infrared
imaging and spectroscopy, complemented with mid-infrared Spitzer/IRAC
imaging, in order to obtain a census of its stellar content and the
nature of its embedded sources. Our observations show that the globule
contains an embedded aggregate of about 30 very young (≲1Myr)
stellar objects, for which we estimate a total mass of ∼90M☉. The
most massive members are three systems containing early B-type stars.
Two of them most likely produced very compact HII regions, one of them
being still highly embedded and coinciding with a peak seen in
emission lines characterising the photon dominated region (PDR). Two
of these three systems are resolved binaries, and one of those
contains a visible Herbig Be star. An approximate derivation of the
mass function of the members of the aggregate gives hints of a slope
at high masses shallower than the classical Salpeter slope, and a peak
of the mass distribution at a mass higher than that at which the
widely adopted log-normal initial mass function peaks. The emission
distribution of H2 and Brackett gamma, tracing the PDR and the
ionised gas phase, respectively, suggests that molecular gas is
distributed as a shell around the embedded aggregate, filled with
centrally-condensed ionised gas. Both, the morphology and the low
excitation of the HII region, indicate that the sources of ionisation
are the B stars of the embedded aggregate, rather than the external UV
field caused by the O stars of Cygnus OB2. The youth of the embedded
cluster, combined with the isolation of the globule, suggests that
star formation in the globule was triggered by the passage of the
ionisation front.
Description:
Table 3 contains positions and photometry in V, R, I, J, H, Ks, [3.6],
[4.5], [5.8] and [8.0] of 144 YSO candidates around the globule
IRAS 20319+3958. The VRI magnitudes and their errors are obtained with
CAMELOT/IAC80 (Tenerife), the JHKs magnitudes and their errors are
obtained with Omega2000/3.5m CAHA telescope (Calar Alto observatory),
except for a few very bright and/or unresolved sources for which
NOTCam/NOT (La Palma) is used. The IRAC/Spitzer magnitudes and errors
are also given. The third last column gives a flag that shows either
the YSO class or the YSO selection method. The naming used in the
paper for the three brightest sources in the globule (A, B and C), of
which two are binaries, are given in the second last column. The last
column gives a photometry flag.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 167 144 YSO candidates
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See also:
J/AJ/150/191 : IR photometry of YSOs in Cygnus-X DR15 (Rivera-Galvez+, 2015)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/144] Identification number
5- 15 F11.7 deg RAdeg Right ascension (J2000)
17- 27 F11.7 deg DEdeg Declination (J2000)
29 A1 --- l_Vmag Upper limit flag on Vmag
30- 34 F5.2 mag Vmag ?=- CAMELOT/IAC80 V-band magnitude
37- 40 F4.2 mag e_Vmag ?=- Error in Vmag
42 A1 --- l_Rmag Upper limit flag on Rmag
43- 47 F5.2 mag Rmag ?=- CAMELOT/IAC80 R-band magnitude
50- 53 F4.2 mag e_Rmag ?=- Error in Rmag
55- 59 F5.2 mag Imag ?=- CAMELOT/IAC80 I-band magnitude
62- 65 F4.2 mag e_Imag ?=- Error in Imag
67 A1 --- l_Jmag Upper limit flag on Jmag
68- 72 F5.2 mag Jmag Omega2000/3.5m J-band magnitude
75- 78 F4.2 mag e_Jmag ?=- Error in Jmag
80- 84 F5.2 mag Hmag Omega2000/3.5m H-band magnitude
87- 90 F4.2 mag e_Hmag Error in Hmag
92- 96 F5.2 mag Ksmag Omega2000/3.5m Ks-band magnitude
99-102 F4.2 mag e_Ksmag Error in Ksmag
104 A1 --- l_[3.6] Upper limit flag on [3.6]
105-109 F5.2 mag [3.6] ?=- IRAC [3.6] magnitude
112-115 F4.2 mag e_[3.6] ?=- Error in [3.6]
117 A1 --- l_[4.5] Upper limit flag on [4.5]
118-122 F5.2 mag [4.5] ?=- IRAC [4.5] magnitude
125-128 F4.2 mag e_[4.5] ?=- Error in [4.5]
130 A1 --- l_[5.8] Upper limit flag on [5.8]
131-135 F5.2 mag [5.8] ?=- IRAC [5.8] magnitude
138-141 F4.2 mag e_[5.8] ?=- Error in [5.8]
143 A1 --- l_[8.0] Upper limit flag on [8.0]
144-148 F5.2 mag [8.0] ?=- IRAC [8.0] magnitude
151-154 F4.2 mag e_[8.0] ?=- Error in [8.0]
156 I1 --- fYSO [1/5] YSO type/selection criteria (1)
158-161 A4 --- Name Other name used in this paper
163-167 A5 --- fPhot [abcde ,] Photometric flag(s) (2)
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Note (1): YSO class or selection criterion:
1 = Class I
2 = Class II
4 = Selection criterion is excess in Ks-[4.5] index
5 = Selection criterion is excess in H-Ks index
Note (2): Photometry flags for one or more bands:
a = Lower magnitude limit for VRI if mag errors n/a
b = Lower magnitude limit for JHK if mag errors n/a
c = NOTCam JHKs photometry used instead of Omega2000 JHKs
d = IRAC fluxes saturated, upper magnitude limit if no mag error
e = IRAC unresolved source
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Acknowledgements:
Anlaug Amanda Djupvik, amanda(at)not.iac.es
References:
Schneider et al., Paper I 2016A&A...591A..40S 2016A&A...591A..40S
(End) Patricia Vannier [CDS] 16-Dec-2016