J/ApJ/743/39 Spitzer observations of W3 molecular cloud (Rivera-Ingraham+, 2011)
Star formation and young stellar content in the W3 giant molecular cloud.
Rivera-Ingraham A., Martin P.G., Polychroni D., Moore T.J.T.
<Astrophys. J., 743, 39 (2011)>
=2011ApJ...743...39R 2011ApJ...743...39R
ADC_Keywords: Molecular clouds ; Photometry, infrared ; YSOs ; Extinction ;
Galaxies, IR
Keywords: infrared: stars - ISM: clouds - stars: pre-main sequence -
ISM: individual objects (Westerhout 3) - stars: formation -
stars: protostars
Abstract:
In this work, we have carried out an in-depth analysis of the young
stellar content in the W3 giant molecular cloud (GMC). The young
stellar object (YSO) population was identified and classified in the
Infrared Array Camera/Multiband Imaging Photometer color-magnitude
space according to the "Class" scheme and compared to other
classifications based on intrinsic properties. Class 0/I and II
candidates were also compared to low-/intermediate-mass
pre-main-sequence (PMS) stars selected through their colors and
magnitudes in the Two Micron All Sky Survey. We find that a reliable
color/magnitude selection of low-mass PMS stars in the infrared
requires prior knowledge of the protostar population, while
intermediate-mass objects can be more reliably identified. By means of
the minimum spanning tree algorithm and our YSO spatial distribution
and age maps, we investigated the YSO groups and the star formation
history in W3.
Description:
In this analysis, we follow up the study initiated by Polychroni et
al. (2010ASPC..424..165P 2010ASPC..424..165P) to characterize the pre-stellar population
in W3 by means of Spitzer data. This analysis will complement the
Herschel data obtained under the guaranteed time key program HOBYS5
(Herschel imaging survey of OB young stellar objects), as well as an
extensive molecular analysis (D. Polychroni et al. 2011, in prep).
The main active regions of W3 were observed by Spitzer under two main
program identification number (PID) programs. The northern parts of
the high-density layer (HDL) comprising W3 Main and W3 (OH) (Figures 1
and 2) were first observed in 2004 under program P00127; AFGL 333 and
central/western region of W3 (including KR 140 and the active region
to its north: "KR 140-N") were subsequently observed in 2007 (program
P30955).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 66 1566 YSOs in each subregion of W3: sample list
table3.dat 66 363 2MASS-based sample of pre-main sequence stars in W3
table4.dat 27 752 Galaxy candidates
table5.dat 69 1566 Photometry for YSOs in each subregion of W3
table15.dat 190 27 Individual parameters of groups in subregions of W3
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See also:
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VI/128 : Log of CGPS exposures (Taylor+, 2003-)
J/ApJS/196/18 : CO survey of galactic molecular clouds. II. (Bieging+, 2011)
J/ApJ/733/113 : IRAC observations of IC 1795 (Roccatagliata+, 2011)
J/ApJ/723/1019 : Galactic SFR and gas surface densities (Heiderman+, 2010)
J/AJ/137/4072 : Infrared photometry of G216-2.5 YSOs (Megeath+, 2009)
J/ApJ/682/445 : Spitzer observations of S254-S258 (Chavarria+, 2008)
J/ApJ/688/1142 : Star formation in W5: Spitzer observations (Koenig+, 2008)
J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)
J/A+A/490/213 : 1.4 and 3.4mm interferometry of W3 IRS5 (Rodon+, 2008)
J/ApJ/654/338 : Spitzer photometry in W3 molecular cloud (Ruch+, 2007)
J/MNRAS/379/663 : 850um observations of W3 giant molecular cloud (Moore+, 2007)
J/AJ/129/393 : UBV photometry in W3 (Oey+, 2005)
J/A+AS/124/205 : W3 star-forming region 345 GHz survey (Helmich+ 1997)
http://starformation-herschel.iap.fr/hobys/ : Star formation with Herschel
Byte-by-byte Description of file: table[23].dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS identifier (HHMMSSss+DDMMSSs; J2000;
only for table 3)
18 I1 h RAh [2] Hour of Right Ascension (J2000)
20- 21 I2 min RAm [17/29] Minute of Right Ascension (J2000)
23- 27 F5.2 s RAs Second of Right Ascension (J2000)
29 A1 --- DE- [+] Sign of Declination (J2000)
30- 31 I2 deg DEd [60/62] Degree of Declination (J2000)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000)
36- 40 F5.2 arcsec DEs Arcsecond of Declination (J2000)
42- 50 A9 --- Class1 Classification in Catalog 1 (G1)
52- 60 A9 --- Class2 Classification in Catalog 2 (G1)
62- 63 I2 --- q1 [-1/1]? Reliability flag of Catalog 1 (G2)
65- 66 I2 --- q2 [-1/1]? Reliability flag of Catalog 2 (G2)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1 I1 h RAh [2] Hour of Right Ascension (J2000)
3- 4 I2 min RAm [17/29] Minute of Right Ascension (J2000)
6- 10 F5.2 s RAs Second of Right Ascension (J2000)
12 A1 --- DE- [+] Sign of Declination (J2000)
13- 14 I2 deg DEd [60/62] Degree of Declination (J2000)
16- 17 I2 arcmin DEm Arcminute of Declination (J2000)
19- 23 F5.2 arcsec DEs Arcsecond of Declination (J2000)
25 I1 --- cl1 [0/1]? Classification in Catalog 1 (1=galaxy) (G1)
27 I1 --- cl2 [1] Classification in Catalog 2 (1=galaxy) (G1)
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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 F6.3 mag [3.6] Spitzer/IRAC 3.6um band magnitude
8- 12 F5.3 mag e_[3.6] Error in [3.6]
14- 19 F6.3 mag [4.5] Spitzer/IRAC 4.5 micron band magnitude
21- 25 F5.3 mag e_[4.5] Error in [4.5]
27- 32 F6.3 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude
34- 39 F6.3 mag e_[5.8] ? Error in [5.8]
41- 46 F6.3 mag [8.0] ? Spitzer/IRAC 8.0um band magnitude
48- 54 F7.3 mag e_[8.0] ? Error in [8.0]
56- 61 F6.3 mag [24] ? Spitzer/MIPS 24um band magnitude
63- 69 F7.3 mag e_[24] ? Error in [24]
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Byte-by-byte Description of file: table15.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Region Region name (AFGL333, KR140FIELD, or
W3_MAIN/OH)
14 I1 h RAh [2] Hour of Right Ascension (J2000)
16- 17 I2 min RAm [19/29] Minute of Right Ascension (J2000)
19- 23 F5.2 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- [+] Sign of Declination (J2000)
26- 27 I2 deg DEd [61/62] Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of Declination (J2000)
38- 46 E9.3 pc2 Area Region area
48- 52 F5.3 mag b_Av Minimum value of Av
54- 58 F5.3 mag B_Av Maximum value of Av
60- 64 F5.3 mag Av [2.2/6.4] Mean V band extinction
66- 73 F8.3 Msun Mgas [20/4300] Gas mass
75- 79 F5.3 Msun e_Mgas Error in Mgas
81- 89 E9.3 Msun/pc2 Sigma [32/95] Gas surface density Σgas
91- 99 E9.3 Msun/pc2 e_Sigma Error in Sigma
101-106 F6.3 pc-2 b_YSO Minium YSO surface density
108-114 F7.3 pc-2 B_YSO Maximum YSO surface density
116-121 F6.3 pc-2 YSO [3/54] Mean YSO surface density
123-131 E9.3 pc-2 e_YSO Error in YSO
133-137 F5.3 --- SFE [0/1] Star formation efficiency (assuming
YSOs are solar-mass stars)
139-143 F5.3 pc b_Dist Minimum neighbor distance
145-149 F5.3 pc B_Dist Maximum neighbor distance
151-155 F5.3 pc Dist [0.07/0.34] Mean neighbor distance
157-165 E9.3 pc e_Dist Error in Dist
167-170 F4.2 pc a [0.4/4.5] Ellipse semi-major axis
172-175 F4.2 --- a/b [1.02/3.33] Axis ratio
177-179 I3 --- N [10/252] Number of YSOs in group
181-182 I2 --- gr [0/10] Group designation in Region
184-190 A7 --- grID Unique group designation
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Global notes:
Note (G1): Photometry derived from the MIPS 24um maps was generally less
reliable. We therefore produced a Catalog 2 (Figure 6) based on the
same procedure as Catalog 1, but allowing for re-classification of
IRAC/2MASS sources only if there was a successful MIPS counterpart in
our original (independently obtained) MIPS source list (i.e., MIPS
centroid (and photometry) not based exclusively on an IRAC detection).
Catalog 2 is therefore more conservative. See section 3.2.1 for
further explanations. The classes are:
class0/I = younger YSOs
class0/I* = younger YSOs, highly embedded
classII = class II transition YSOs
classII* = class II transition YSOs, highly embedded
ttauri = T Tau star (class III)
herbig = Herbig Ae/Be star (catalog 2 only)
nomatch = no match for YSO (catalog 2 only)
Note (G2): Reliability flag as follows (details in section 3.2.1):
1 = All sources successfully classified as YSO candidates and satisfying
all the cleaning conditions and bandmerging requirements
0 = Additional detections satisfying all the catalog requirements and with
detections in IRAC channels 1 and 2 (with the best sensitivity).
Photometry was performed on fixed centroids at longer wavelengths
(including MIPS), and all the cleaning/selection conditions and the
Gutermuth classification scheme were again applied to each source.
-1 = Not applicable
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Nomenclature note:
For table2 (and 5), YSOs are <[RMP2011] JHHMMSS.ss+DDMMSS.ss> in Simbad.
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 29-Apr-2013