J/AJ/154/163 WISE-selected candidate SFRs beyond the Outer Arm (Izumi+, 2017)
Star formation activity beyond the Outer Arm.
I. WISE-selected candidate star-forming regions.
Izumi N., Kobayashi N., Yasui C., Saito M., Hamano S.
<Astron. J., 154, 163 (2017)>
=2017AJ....154..163I 2017AJ....154..163I (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Molecular clouds ; Star Forming Region ;
Photometry, infrared
Keywords: Galaxy: formation - infrared: stars - ISM: clouds - stars: formation
Abstract:
The outer Galaxy beyond the Outer Arm provides a good opportunity to
study star formation in an environment significantly different from
that in the solar neighborhood. However, star-forming regions in the outer
Galaxy have never been comprehensively studied or cataloged because of
the difficulties in detecting them at such large distances. We studied
33 known young star-forming regions associated with 13 molecular clouds
at RG≥13.5 kpc in the outer Galaxy with data from the Wide-field
Infrared Survey Explorer (WISE) mid-infrared all-sky survey (Wright et al.
2010AJ....140.1868W 2010AJ....140.1868W; Jarrett et al. 2011ApJ...735..112J 2011ApJ...735..112J). From their
color distribution, we developed a simple identification criterion of
star-forming regions in the outer Galaxy with the WISE color. We
applied the criterion to all the WISE sources in the molecular clouds
in the outer Galaxy at RG≥13.5 kpc detected with the Five College
Radio Astronomy Observatory (FCRAO) 12CO survey of the outer Galaxy
(Heyer et al. 1998ApJS..115..241H 1998ApJS..115..241H), of which the survey region is
102.49°=<l=<141.54°, -3.03°=<b=<5.41°, and
successfully identified 711 new candidate star-forming regions in 240
molecular clouds. The large number of samples enables us to perform
the statistical study of star formation properties in the outer Galaxy
for the first time. This study is crucial to investigate the
fundamental star formation properties, including star formation rate,
star formation efficiency, and initial mass function, in a primordial
environment such as the early phase of the Galaxy formation.
Description:
In this paper, we use the WISE MIR all-sky survey data (Wright et al.
2010AJ....140.1868W 2010AJ....140.1868W; Jarrett et al. 2011ApJ...735..112J 2011ApJ...735..112J) and FCRAO 12CO
survey data of the outer Galaxy (Heyer et al. 1998ApJS..115..241H 1998ApJS..115..241H).
WISE mapped at least eight times over 99% of the sky in four MIR bands
centered at 3.4, 4.6, 12, and 22 µm in the six-month survey in 2010
(Wright et al. 2010AJ....140.1868W 2010AJ....140.1868W). We used the AllWISE Source Catalog
(http://wise2.ipac.caltech.edu/docs/release/allwise/) to obtain the
WISE magnitudes and colors of the sample star-forming regions.
The FCRAO 12CO survey of the outer Galaxy (Heyer et al. 1998) has
achieved the best combination of large-area coverage and high sensitivity
among all of the available CO surveys of the outer Galaxy. In this
paper, we employed the molecular cloud catalog by Brunt et al. (2003,
J/ApJS/144/47) to make use of the larger number of clouds compared
with the original catalog by Heyer et al. (2001, J/ApJ/551/852).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 13 Molecular clouds with associating sample
star-forming regions in the FOG and EOG
table2.dat 126 99 Sample and candidate star-forming regions and
the WISE sources in the outer Galaxy
table3.dat 50 15 Contamination rate for molecular clouds with
associating sample star-forming regions
table4.dat 75 252 Molecular clouds with associating new candidate
star-forming regions
table5.dat 103 792 New candidate star-forming regions
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See also:
II/328 : AllWISE Data Release (Cutri+ 2013)
J/ApJ/551/852 : FCRAO CO survey of the outer Galaxy (Heyer+, 2001)
J/A+A/399/1083 : Outer Galaxy IRAS sources and 12CO emission (Kerton+, 2003)
J/ApJS/144/47 : Outer galaxy molecular cloud catalog (Brunt+, 2003)
J/A+A/464/909 : JHK photometry near IRAS 06145+1455 (Brand+, 2007)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/ApJS/224/7 : CO obs. of the outer arm in the 2nd quadrant (Du+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Region [EOG FOG] Region (EOG=Extreme Outer Galaxy,
FOG=Far Outer Galaxy)
5- 20 A16 --- Cloud Molecular cloud identifier
22- 28 F7.3 deg GLON [130.539/195.82] Galactic longitude
30- 35 F6.3 deg GLAT [-1/2.797] Galactic latitude
37- 43 F7.2 km/s VLSR [-102.4/34.01] Local standard of rest velocity
of cloud
45- 48 F4.1 kpc Dist [6.3/16] Kinematic distance
50- 53 F4.1 kpc Rgal [13.5/22] Galactocentric radius
55 A1 --- l_Age [<] Limit flag on Age
56- 58 F3.1 Myr b_Age [0.5/1]? Minimum of cloud age range
60- 62 F3.1 Myr B_Age [1]? Maximum of cloud age range
64- 68 A5 --- Ref References (1)
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Note (1): Reference as follows:
1 = Digel et al. (1994ApJ...422...92D 1994ApJ...422...92D);
2 = Izumi et al. (2014ApJ...795...66I 2014ApJ...795...66I);
3 = Kobayashi et al. (2008ApJ...683..178K 2008ApJ...683..178K);
4 = Yasui et al. (2008ApJ...675..443Y 2008ApJ...675..443Y);
5 = Brand & Wouterloot (1994A&AS..103..503B 1994A&AS..103..503B);
6 = Brand & Wouterloot (2007, J/A+A/464/909);
7 = Heyer et al. (1998ApJS..115..241H 1998ApJS..115..241H);
8 = Snell et al. (2002ApJ...578..229S 2002ApJ...578..229S).
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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- 3 A3 --- Region [EOG FOG] Region (EOG=Extreme Outer Galaxy,
FOG=Far Outer Galaxy)
5- 20 A16 --- Cloud Molecular cloud identifier
22- 32 A11 --- SFR Previous identification of the star-forming
region (1)
34- 39 A6 --- Type SFR type (2)
41- 59 A19 --- WISE ALLWISE position based identifier
61- 67 F7.3 deg GLON [130.54/195.823] Galactic longitude of ALLWISE
source
69- 74 F6.3 deg GLAT [-1.108/2.767] Galactic latitude of ALLWISE
source
76- 81 F6.3 mag W1mag [9.211/17.11] ALLWISE W1 (3.35µm) band
magnitude
83- 87 F5.3 mag e_W1mag [0.016/0.191] Uncertainty in W1mag
89- 94 F6.3 mag W2mag [7.435/15.844] ALLWISE W2 (4.6µm) band
magnitude
96-100 F5.3 mag e_W2mag [0.014/0.153] Uncertainty in W2mag
102-107 F6.3 mag W3mag [3.379/11.362] ALLWISE W3 (11.6µm) band
magnitude
109-113 F5.3 mag e_W3mag [0.005/0.212] Uncertainty in W3mag
115-120 F6.3 mag W4mag [-0.009/8.802] ALLWISE W4 (22.1µm) band
magnitude
122-126 F5.3 mag e_W4mag [0.004/0.526]? Uncertainty in W4mag (G2)
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Note (1): Star forming regions are defined as follows:
Q = Star-forming region (cluster/stellar aggregates) unpublished yet
but separately identified from our Subaru and QUIRC data
(Izumi et al. 2017, in preparation);
CAN = Candidate star-forming region newly identified with the WISE data
(Wright et al. 2010AJ....140.1868W 2010AJ....140.1868W; Jarrett et al. 2011ApJ...735..112J 2011ApJ...735..112J);
see Section 3.1.
Other star-forming regions are literature ID from Kobayashi et al.
(2008ApJ...683..178K 2008ApJ...683..178K), Yasui et al. (2008ApJ...675..443Y 2008ApJ...675..443Y), Snell et al.
(2002ApJ...578..229S 2002ApJ...578..229S) or Izumi et al. (2014ApJ...795...66I 2014ApJ...795...66I).
Note (2): Star forming region type as follows:
A = Aggregate;
EC = Embedded cluster;
EC+HII = Embedded cluster with HII region, Snell et al. (2002ApJ...578..229S 2002ApJ...578..229S).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Cloud Molecular cloud identifier
18- 22 A5 --- Source Survey data source (NRO, FCRAO)
24- 25 I2 --- NSFR [0/25]? Number of SFR and candidate SFR in
the cloud
27- 29 I3 arcmin2 Area [18/130]? Cloud area
31- 36 E6.4 arcmin-2 dSFR [0.024/0.54]? Density of SFR and candidate SFR
in the cloud
38- 40 I3 --- NCand [21/147]? Number of candidate SFR in the field
42- 47 E6.4 arcmin-2 dCand [0.0072/0.054]? Density of candidate SFR in
in the field
49- 50 I2 % Cont [3/54]? Contamination rate
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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- 9 A9 --- --- ([BKP2003] )
10- 14 I5 --- [BKP2003] Cloud identification number ([BKP2003]NNNNN)
(G1)
16- 22 F7.3 deg GLON [102.632/141.464] Galactic longitude (G1)
24- 29 F6.3 deg GLAT [-2.044/5.099] Galactic latitude (G1)
31- 37 F7.2 km/s VLSR [-107.35/-50.66] Local standard of rest velocity
of cloud centroid (G1)
39- 43 F5.2 kpc Dist [5.8/21.5] Kinematic distance (1)
45- 48 F4.1 kpc Rgal [13.5/28.3] Galactocentric radius
50- 51 I2 --- NCand [1/24] Number of candidate(s) in the cloud
53- 58 F6.2 % Cont [1/231] Contamination rate
60- 75 A16 --- Note Note (2)
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Note (1): Distances derived assuming that the rotation speed of the Sun and
BKP clouds is 220 km/s and that the Galactocentric distance of the
Sun is 8.5 kpc.
Note (2): Notes include the name of the 12 molecular clouds, which were used as
molecular clouds with associating sample star-forming regions
(Table 3, Figures 2 and 5). CO peak of Digel Cloud 1a were not
detected from FCRAO CO survey of the outer Galaxy.
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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- 9 A9 --- --- ([BKP2003] )
10- 14 I5 --- [BKP2003] Cloud identification number ([BKP2003]NNNNN)
(G1)
16- 16 A1 --- f_ID [m] Multiple clouds flag for source (1)
18- 36 A19 --- WISE ALLWISE position based identifier
38- 44 F7.3 deg GLON [102.59/141.479] Galactic longitude of ALLWISE
source
46- 51 F6.3 deg GLAT [-2.04/5.14] Galactic latitude of ALLWISE
source
53- 58 F6.3 mag W1mag [7.879/17.537] ALLWISE W1 (3.35µm) band
magnitude
60- 64 F5.3 mag e_W1mag [0.014/0.213] Uncertainty in W1mag
66- 71 F6.3 mag W2mag [6.733/16.202] ALLWISE W2 (4.6µm) band
magnitude
73- 77 F5.3 mag e_W2mag [0.014/0.195] Uncertainty in W2mag
79- 84 F6.3 mag W3mag [1.41/12.184] ALLWISE W3 (11.6µm) band
magnitude
86- 90 F5.3 mag e_W3mag [0.005/0.219] Uncertainty in W3mag
92- 97 F6.3 mag W4mag [-2.147/9.441] ALLWISE W4 (22.1µm) band
magnitude
99-103 F5.3 mag e_W4mag [0.002/0.542]? Uncertainty in W4mag (G2)
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Note (1): More than one cloud at different velocities exist in the line of
sight for 13 candidates marked with "m".
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Global notes:
Note (G1): Identifiers (Tables 4 and 5), positions, and VLSR (Table 4) taken
from the cloud catalog of Brunt et al. (2003, J/ApJS/144/47).
Note (G2): A null value indicates the profile-fit magnitude is a 95% confidence
upper limit or the source is not measurable.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 17-Jul-2018