J/ApJ/710/150 Molecular lines in EGOs (Chen+, 2010)
A search for infall evidence in EGOs.
I. The northern sample.
Chen X., Shen Z.-Q., Li J.-J., Xu Y., He J.-H.
<Astrophys. J., 710, 150-169 (2010)>
=2010ApJ...710..150C 2010ApJ...710..150C
ADC_Keywords: Carbon monoxide ; Line Profiles ; Radio lines ; Infrared sources ;
Interstellar medium ; YSOs
Keywords: ISM: kinematics and dynamics - ISM: molecules - radio lines: ISM -
stars: formation
Abstract:
We report the first systematic survey of molecular lines (including
HCO+(1-0) and 12CO, 13CO, C18O(1-0) lines at the 3mm band)
toward a new sample of 88 massive young stellar object (MYSO)
candidates associated with ongoing outflows (known as extended green
objects or EGOs) identified from the Spitzer GLIMPSE survey in the
northern hemisphere with the Purple Mountain Observatory 13.7m radio
telescope. By analyzing the asymmetries of the optically thick line
HCO+ for 69 of 72 EGOs with HCO+ detection, we found 29 sources
with "blue asymmetric profiles" and 19 sources with "red asymmetric
profiles."
Description:
Single-point observations were carried out toward 88 EGOs with
δ>-20° compiled from an extended green objects (EGO) catalog
(Cyganowski et al. 2008, Cat. J/AJ/136/2391) using the 13.7m telescope
of the Purple Mountain Observatory (PMO) in Delingha, China. The
sample includes 50 "likely" massive young stellar object (MYSO)
outflow candidate EGOs selected from Tables 1, 2, and 5 of Cyganowski
et al. (2008, Cat. J/AJ/136/2391) and 38 "possible" MYSO outflow
candidate EGOs selected from Tables 3 and 4. HCO+ line was observed
in 2009 Jan 9-23 with a spectral resolution of 0.205km/s; 12CO line,
13CO line and C18O line were observed in 2009 Feb 12-17 with a
spectral resolution of 0.369km/s, 0.114km/s and 0.115km/s,
respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 42 88 Sample parameters
table3.dat 68 119 Observed HCO+(1-0) line properties of all 88
sample sources
table4.dat 53 31 *Gaussian fits to HCO+ line wings
table6.dat 146 77 Observed CO(1-0) line properties of 72 sources
table7.dat 73 69 Derived line asymmetric parameters and
source physical properties for 69 sources
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Note on table4.dat: The Gaussian fits listed here were subtracted from the
HCO+ spectra before analyzing the main line profile.
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See also:
J/ApJS/196/9 : 95GHz methanol maser survey toward GLIMPSE EGOs (Chen+, 2011)
J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010)
J/ApJ/702/1615 : CH3OH maser survey of EGOs (Cyganowski+, 2009)
J/AJ/136/2391 : GLIMPSE Extended Green Objects catalog (Cyganowski+, 2008)
J/MNRAS/301/640 : Ultracompact H II regions studies. II. (Walsh+, 1998)
J/ApJS/91/659 : Ultracompact HII regions radio images (Kurtz+ 1994)
J/ApJS/91/347 : A 5-GHz VLA Survey of the Galactic Plane (Becker+ 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Source name (GLL.ll+B.bb)
13- 14 I2 h RAh Hour of right ascension (J2000) (1)
16- 17 I2 min RAm Minute of right ascension (J2000)
19- 22 F4.1 s RAs Second of right ascension (J2000)
24 A1 --- DE- Sign of declination (J2000) (1)
25- 26 I2 deg DEd Degree of declination (J2000) (1)
28- 29 I2 arcmin DEm Arcminute of declination (J2000)
31- 32 I2 arcsec DEs Arcsecond of declination (J2000)
34 A1 --- IRDC [Y/N] Association with IR dark clouds (2)
36 A1 --- CH3OH [Y/N]? Associations with 6.7GHz class II
methanol masers (3)
38 A1 --- UCHII [Y/N]? Associations with ultra-compact
HII regions (3)
40 A1 --- 1.1mm [Y/N]? Associations with 1.1mm continuum
sources (3)
42 I1 --- C08 [1-5] Sources in Cyganowski et al. 2008 (4)
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Note (1): The targeted positions in the observations are from the EGO positions
presented by the EGO catalog of Cyganowski et al. (2008,
Cat. J/AJ/136/2391; in Simbad).
Note (2): Association with IR dark clouds : "Y", Yes; "N", No; presented by
Cyganowski et al. (2008, Cat. J/AJ/136/2391).
Note (3): Associations with 6.7GHz class II methanol masers, UC HII regions and
1.1mm continuum sources within 30": "Y", Yes; "N", No; identified from
the 6.7GHz maser catalogs (Szymczak et al. 2007A&A...468..617S 2007A&A...468..617S;
Cyganowski et al. 2008, Cat. J/AJ/136/2391, 2009, Cat. J/ApJ/702/1615;
Caswell 2009PASA...26..454C 2009PASA...26..454C; Xu et al. 2009A&A...507.1117X 2009A&A...507.1117X) and UC HII
catalogs (Wood & Churchwell 1989ApJS...69..831W 1989ApJS...69..831W; Becker et al. 1994,
Cat. J/ApJS/91/347; Kurtz et al. 1994, Cat. J/ApJS/91/659; Walsh et
al. 1998, Cat. J/MNRAS/301/640; Forster & Caswell 2000ApJ...530..371F 2000ApJ...530..371F;
Wu et al. 2007ApJ...669L..37W 2007ApJ...669L..37W), and 1.1mm continuum BOLOCAM GPS
archive (Rosolowsky et al. 2010, Cat. J/ApJS/188/123).
Note (4): Remarks: "1"-"5" represent that the sources are selected from Tables
1-5 of Cyganowski et al. (2008, Cat. J/AJ/136/2391), respectively.
"1", "2", and "5" are classified as "likely" outflow candidates, while
3 and 4 are classified as "possible" outflow candidates.
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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- 11 A11 --- Name Source name (GLL.ll+B.bb)
12 A1 --- f_Name [bcd] Peculiar profile (1)
14- 18 F5.2 K.km/s TdV ? Integrated intensity (∫TMBdV)
20- 23 F4.2 K.km/s e_TdV ? TdV uncertainty
25- 30 F6.2 km/s Vlsr ? Velocity at peak VLSR
32- 35 F4.2 km/s e_Vlsr ? Vlsr uncertainty
37- 41 F5.2 km/s DelV ? Line width ΔV
43- 46 F4.2 km/s e_DelV ? DelV uncertainty
48- 51 F4.2 K Tmb ? Peak main beam temperature TMB (2)
53- 56 F4.2 K Tmb2 ? Real observed TMB (3)
58- 63 F6.2 km/s Vlsrpk ? Observed VLSR at HCO+ spectral peaks
for double-peaked and skewed profiles (3)
65- 68 F4.2 K rms ? 1σ noise in the observed HCO+
spectrum at TMB scale
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Note (1): Flag as follows:
b = Sources with non-asymmetric profiles (21 in total).
c = Sources with complex HCO+ spectral profiles. They were not used in
analysis for the line asymmetry (see Section 3.2).
d = No HCO+ emission detected (16 sources in total).
Note (2): The peak main beam temperature TMB estimated from Gaussian fits to
HCO+ lines after masking the absorption dips and subtracting
Gaussian fits to any line wings (see Table 5).
Note (3): The peak position is used to analyze line asymmetry (see Section 3.2).
For non-asymmetric profile sources, the real observed TMB and VLSR
adopt the Gaussian fit values in Columns "Tmb" and "Vlsr". Their
uncertainties are assumed to be the 1σ noise of HCO+ spectrum
listed in Column "rms" and one-half the channel width, respectively.
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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- 11 A11 --- Name Source name (GLL.ll+B.bb)
12 A1 --- f_Name [c] Peculiar profile (1)
14- 18 F5.2 K.km/s TdV Integrated intensity (∫TMBdV)
20- 23 F4.2 K.km/s e_TdV TdV uncertainty
25- 30 F6.2 km/s Vlsr Velocity at peak VLSR
32- 35 F4.2 km/s e_Vlsr Vlsr uncertainty
37- 41 F5.2 km/s DelV Line width (ΔV)
43- 46 F4.2 km/s e_DelV DelV uncertainty
48- 51 F4.2 K Tmb Peak main beam temperature (TMB)
determined from single broad Gaussian fit to
HCO+ line wing
53 A1 --- line [DBR] Double/Blue/Red line wing shape (2)
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Note (1):
c = As there are strong emissions at the blue- and redshifted wings of this
source (see Figure 1), two separate components (rather than a single
broad component) were used to fit the strong blue- and redshifted wings.
Note (2): Line wing shape classified as:
D = the line wing emission is from both blue- and redshifted (double) wings
B = the line wing emission is mainly from blueshifted wing
R = the line wing emission is mainly from redshifted wing
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Source name (GLL.ll+B.bb)
12 A1 --- f_Name [ab] Flag on Name (1)
14- 19 F6.2 K.km/s TdV12 12CO integrated intensity ∫TMBdV
21- 24 F4.2 K.km/s e_TdV12 TdV12 uncertainty
26- 31 F6.2 km/s Vlsr12 12CO velocity at peak VLSR
33- 36 F4.2 km/s e_Vlsr12 Vlsr12 uncertainty
38- 42 F5.2 km/s DelV12 12CO line width ΔV
44- 47 F4.2 km/s e_DelV12 DelV12 uncertainty
49- 53 F5.2 K Tmb12 Peak main beam temperature TMB for 12CO
line determined from a single-Gaussian fit
55- 58 F4.2 K rms12 ? 1σ noise in the observed 12CO
spectrum at TMB scale
60- 64 F5.2 K.km/s TdV13 13CO integrated intensity ∫TMBdV
66- 69 F4.2 K.km/s e_TdV13 TdV13 uncertainty
71- 76 F6.2 km/s Vlsr13 13CO velocity at peak VLSR
78- 81 F4.2 km/s e_Vlsr13 Vlsr13 uncertainty
83- 86 F4.2 km/s DelV13 13CO line width ΔV
88- 91 F4.2 km/s e_DelV13 DelV13 uncertainty
93- 97 F5.2 K Tmb13 Peak main beam temperature TMB for 13CO
line determined from a single-Gaussian fit
99-102 F4.2 K rms13 ? 1σ noise in the observed 13CO
spectrum at TMB scale
104-108 F5.2 K.km/s TdV18 C18O integrated intensity ∫TMBdV
110-113 F4.2 K.km/s e_TdV18 TdV18 uncertainty
115-120 F6.2 km/s Vlsr18 C18O velocity at peak VLSR
122-125 F4.2 km/s e_Vlsr18 Vlsr18 uncertainty
127-131 F5.2 km/s DelV18 C18O line width ΔV
133-136 F4.2 km/s e_DelV18 DelV18 uncertainty
138-141 F4.2 K Tmb18 Peak main beam temperature TMB for C18O
line determined from a single-Gaussian fit
143-146 F4.2 K rms18 ? 1σ noise in the observed C18O
spectrum at TMB scale
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Note (1): Flag as follows:
a = Sources with complex C18O spectral profiles. They were not used in
analysis for the line asymmetry (see Section 3.2).
b = 12CO was used to calculate the optical depth of C18O with typical
LTE method for these sources (see Section 3.2).
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Source name (GLL.ll+B.bb)
13- 17 F5.2 --- delV HCO+ line asymmetry parameter δV (2)
19- 22 F4.2 --- e_delV delV uncertainty (1)
24- 27 F4.2 --- TB/TR ? HCO+ line asymmetry parameters determined
by the TMB(B)/TMB(R) method (Section 3.2)
29- 32 F4.2 --- e_TB/TR ? TB/TR uncertainty (1)
34 A1 --- P [NBR] Non-asymmetric, Blue or Red profile (2)
36- 39 F4.2 --- tau Optical depth of C18O line
41- 44 F4.1 kpc Dist Kinematic distance to source (3)
46- 49 F4.2 --- f Beam filling factor
51- 54 F4.2 pc Size Linear size
56- 59 F4.1 10+16cm-2 NC18O Column density of C18O
61- 63 F3.1 10+23cm-2 NH2 Column density of H2
65- 67 F3.1 10+5cm-3 nH2 Volume density of H2
69- 73 I5 Msun Mass Core mass
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Note (1): Uncertainties calculated from the rms uncertainties in temperatures
and one-half the channel widths.
Note (2): δV is the ratio (Vthick-Vthin)/ΔVthin where
Vthick and Vthin are the peak velocities of the optically thick
and optically thin lines, and ΔVthin the line width of the
optically thin line. We adopt δV of ±0.25 as the threshold
to define the line asymmetry. For double-peaked profile, the velocity
at the brightest peak is adopted as the value of Vthick to calculate
δV, and we consider an asymmetry to be significant if the
difference (or sum) between TMB(B)/TMB(R) and its uncertainty is
still larger (or less) than 1 for blue (or red) double-peaked profile.
The line profile is then classified as Blue, Red or Non-asymmetric.
Note (3): The near kinematic distance was adopted for source with near/far
distance ambiguity. The distances to G49.07-0.33, G49.27-0.32,
G49.27-0.34 and G59.79+0.63 are assumed to be 5kpc.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 12-Mar-2012