J/ApJ/778/96 Spitzer and NEWFIRM observations of NGC 6334 (Willis+, 2013)
A wide-field near- and mid-infrared census of young stars in NGC 6334.
Willis S., Marengo M., Allen L., Fazio G.G., Smith H.A., Carey S.
<Astrophys. J., 778, 96 (2013)>
=2013ApJ...778...96W 2013ApJ...778...96W
ADC_Keywords: Photometry, infrared ; YSOs ; Molecular clouds
Keywords: ISM: individual: NGC 6334; stars: formation
Abstract:
This paper presents a study of the rate and efficiency of star
formation in the NGC 6334 star-forming region. We obtained
observations at J, H, and Ks taken with the NOAO Extremely
Wide-Field Infrared Imager and combined them with observations taken
with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope
at wavelengths = 3.6, 4.5, 5.8, and 8.0µm. We also analyzed
previous observations taken at 24µm using the Spitzer MIPS camera
as part of the MIPSGAL survey. We have produced a point source catalog
with >700000 entries. We have identified 2283 young stellar object
(YSO) candidates, 375 Class I YSOs, and 1908 Class II YSOs using a
combination of existing IRAC-based color classification schemes that
we have extended and validated to the near-IR for use with warm
Spitzer data. We have identified multiple new sites of ongoing star
formation activity along filamentary structures extending tens of
parsecs beyond the central molecular ridge of NGC 6334. By mapping the
extinction, we derived an estimate for the gas mass,
2.2x105M☉. The heavy concentration of protostars along the
dense filamentary structures indicates that NGC 6334 may be undergoing
a "mini-starburst" event with ΣSFR>8.2M☉M/yr/pc2 and
SFE>0.10. We have used these estimates to place NGC 6334 in the
Kennicutt-Schmidt diagram to help bridge the gap between observations
of local low-mass star-forming regions and star formation in other
galaxies.
Description:
We observed a 1.2° by 0.9° region covering NGC 6334 (shown in
Figure 3) using IRAC during Spitzer's cryogenic mission on 2008
September 21 (PID 30154) at 3.6, 4.5, 5.8, and 8.0um. We also
retrieved the archival MIPSGAL 24um observations of NGC 6334 obtained
as part of the MIPSGAL survey (Carey et al. 2009PASP..121...76C 2009PASP..121...76C).
Figure 4 shows our near-IR images of NGC 6334 acquired with the
NEWFIRM camera on the Blanco 4m telescope at CTIO during the 2010A
semester from 2010 May 24 to 30.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 152 708805 NGC 6334 point source catalog
table5.dat 159 2281 NGC 6334 young stellar objects catalog
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See also:
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
II/337 : VISTA Variables in the Via Lactea Survey DR1 (Minniti+, 2014)
J/A+A/558/A53 : MW global survey of star clusters. II. (Kharchenko+, 2013)
J/ApJS/209/28 : MYStIX Wide-Field NIR data: crowded fields (King+, 2013)
J/AJ/144/31 : IR photometry of protostar candidates (Kryukova+, 2012)
J/ApJ/749/79 : Transition disks. II. Southern MoC (Romero+, 2012)
J/A+A/538/A142 : OB stars in NGC 6334 and NGC 6357 (Russeil+, 2012)
J/MNRAS/411/1597 : LMC point source classification in SAGE-Spec (Woods+, 2011)
J/ApJ/723/1019 : Galactic SFR and gas surface densities (Heiderman+, 2010)
J/ApJ/707/1 : Water and Methanol masers in NGC 6334I(N) (Brogan+, 2009)
J/ApJS/185/198 : The Cepheus flare observed with IRAC and MIPS (Kirk+, 2009)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/AJ/138/227 : Stellar clusters in NGC 6334 complex (Feigelson+, 2009)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)
J/ApJ/680/495 : Interstellar clouds in the Gould belt (Harvey+, 2008)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/A+A/316/102 : JHK Photometry in NGC 6334 (Tapia+, 1996)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Seq [1/708805] Catalog running sequence number
8- 9 I2 h RAh [17] Hour of Right Ascension (J2000)
11- 12 I2 min RAm [17/22] Minute of Right Ascension (J2000)
14- 19 F6.3 s RAs Second of of Right Ascension (J2000)
21 A1 --- DE- [-] Sign of the Declination (J2000)
22- 23 I2 deg DEd [35/36] Degree of Declination (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination (J2000)
28- 32 F5.2 arcsec DEs Arcsecond of Declination (J2000)
34- 39 F6.3 mag Jmag [11.8/21.1]? NEWFIRM J band magnitude
41- 45 F5.3 mag e_Jmag [0/0.3]? Uncertainty in Jmag
47- 52 F6.3 mag Hmag ? NEWFIRM H band magnitude
54- 58 F5.3 mag e_Hmag ? Uncertainty in Hmag
60- 65 F6.3 mag Kmag [9.7/17.8]? NEWFIRM Ks band magnitude
67- 71 F5.3 mag e_Kmag [0.006/0.3]? Uncertainty in Kmag
73- 78 F6.3 mag [3.6] ? Spitzer/IRAC 3.6 micron band magnitude
80- 84 F5.3 mag e_[3.6] ? Uncertainty in [3.6]
86- 91 F6.3 mag [4.5] [2.6/17.4]? Spitzer/IRAC 4.5um band magnitude
93- 97 F5.3 mag e_[4.5] [0.001/0.3]? Uncertainty in [4.5]
99-104 F6.3 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude
106-110 F5.3 mag e_[5.8] ? Uncertainty in [5.8]
112-117 F6.3 mag [8.0] [1.8/14.7]? Spitzer/IRAC 8.0um band magnitude
119-123 F5.3 mag e_[8.0] [0.007/0.3]? Uncertainty in [8.0]
125-129 F5.3 mag [24] [0.6/9.3]? Spitzer/MIPS 24um band magnitude
131-135 F5.3 mag e_[24] [0.007/0.5]? Uncertainty in [24]
137-152 A16 --- Class Classification (1)
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Note (1): Classifications found are:
FieldStar = field star (f*)
IRACCLASSI = IRAC-selected Class I YSO (ICI)
IRACCLASSII = IRAC-selected Class II YSO (ICII)
NIR2CUTPAH_YSO = (N2YP)
NIR2CUTYSO = (N2Y)
HKKI2YSO = (HKY)
HKKI2YSO_PAH = (HKYP)
KI1I1I2YSO = (KIY)
KI1I1I2YSO_PAH = (KIYP)
SHOCK_KNOT = Shock YSO (SK)
PAHCONTAMINATED = PAH Contaminated Aperture (PAHC)
PAH_GALAXY = PAH Galaxy (PAHG)
AGN = Active Galaxy Nucleus
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Seq [1/708805] Catalog running sequence number
8- 9 I2 h RAh [17] Hour of Right Ascension (J2000)
11- 12 I2 min RAm [17/22] Minute of Right Ascension (J2000)
14- 19 F6.3 s RAs Second of of Right Ascension (J2000)
21 A1 --- DE- [-] Sign of the Declination (J2000)
22- 23 I2 deg DEd [35/36] Degree of Declination (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination (J2000)
28- 32 F5.2 arcsec DEs Arcsecond of Declination (J2000)
34- 39 F6.3 mag Jmag [11.8/21.1]? NEWFIRM J band magnitude
41- 45 F5.3 mag e_Jmag [0/0.3]? Uncertainty in Jmag
47- 52 F6.3 mag Hmag ? NEWFIRM H band magnitude
54- 58 F5.3 mag e_Hmag ? Uncertainty in Hmag
60- 65 F6.3 mag Kmag [9.7/17.8]? NEWFIRM Ks band magnitude
67- 71 F5.3 mag e_Kmag [0.006/0.3]? Uncertainty in Kmag
73- 78 F6.3 mag [3.6] ? Spitzer/IRAC 3.6 micron band magnitude
80- 84 F5.3 mag e_[3.6] ? Uncertainty in [3.6]
86- 91 F6.3 mag [4.5] [2.6/17.4]? Spitzer/IRAC 4.5um band magnitude
93- 97 F5.3 mag e_[4.5] [0.001/0.3]? Uncertainty in [4.5]
99-104 F6.3 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude
106-110 F5.3 mag e_[5.8] ? Uncertainty in [5.8]
112-117 F6.3 mag [8.0] [1.8/14.7]? Spitzer/IRAC 8.0um band magnitude
119-123 F5.3 mag e_[8.0] [0.007/0.3]? Uncertainty in [8.0]
125-129 F5.3 mag [24] [0.6/9.3]? Spitzer/MIPS 24um band magnitude
131-135 F5.3 mag e_[24] [0.007/0.5]? Uncertainty in [24]
137-142 A6 --- Class Classification (1)
154-159 F6.3 --- SpInd [-3.9/6.1] Spectral index fit from Ks band
longward
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Note (1): Classification as follows:
ICI = IRAC-selected Class I YSO;
ICII = IRAC-selected Class II YSO;
NIRCI = Near-Infrared-selected Class I YSO;
NIRCII = Near-Infrared-selected Class II YSO;
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 23-Apr-2015