J/MNRAS/499/6018 Shocks in high-mass starless clump candidates (Zhu+, 2020)
Searching for shocks in high-mass starless clump candidates.
Zhu F.-Y., Wang J.-Z., Liu T., Kim K.-T., Zhu Q.-F., Li F.
<Mon. Not. R. Astron. Soc., 499, 6018-6034 (2020)>
=2020MNRAS.499.6018Z 2020MNRAS.499.6018Z (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Protostars ; Star Forming Region ;
Abundances, peculiar ; Radio lines
Keywords: shock waves - stars: formation - stars: protostars - ISM: structure -
radio lines: ISM
Abstract:
In order to search for shocks in the very early stage of star
formation, we performed single-point surveys of SiO J=1-0, 2-1, and
3-2 lines and the H2CO 212-111 line towards a sample of 100
high-mass starless clump candidates (SCCs) by using the Korean VLBI
Network (KVN) 21-m radio telescopes. The detection rates of the SiO
J=1-0, 2-1, 3-2 lines, and the H2CO line are 31.0, 31.0, 19.5, and
93.0 per cent, respectively. Shocks seem to be common in this stage of
massive star formation. The widths of the observed SiO lines [full
width at zero power (FWZP)] range from 3.4 to 55.1km/s. A significant
fraction (∼29 per cent) of the detected SiO spectra have broad line
widths (FWZP>20km/s), which are very likely associated with fast
shocks driven by protostellar outflows. This result suggests that
about one third of the SiO-detected SCCs are not really starless but
protostellar. On the other hand, about 40 per cent of the detected SiO
spectra show narrow line widths (FWZP<10km/s) probably associated with
low-velocity shocks which are not necessarily protostellar in origin.
The estimated SiO column densities are mostly 0.31-4.32x1012cm-2.
Comparing the SiO column densities derived from SiO J=1-0 and 2-1
lines, we suggest that the SiO molecules in the SCCs may be in the
non-LTE condition. The SiO abundances to H2 are usually
0.20-10.92x10-10.
Description:
The sample in this study consists of 100 SCCs, which have been
observed by Calahan et al. (2018ApJ...862...63C 2018ApJ...862...63C) to search for infall
signatures. These targets were blindly selected from the SCC catalogue
of Svoboda et al. (2016ApJ...822...59S 2016ApJ...822...59S, Cat. J/ApJ/822/59) with
NH3(1,1) detections. The distances of these sources range from 1.18
to 11.8kpc and the average and median distances are 4.32 and 4.19kpc,
respectively (Ellsworth-Bowers et al. 2015ApJ...799...29E 2015ApJ...799...29E, Cat.
J/ApJ/799/29).
We conducted single-point molecular line observations using all three
(Yonsei, Ulsan and Tamma) KVN 21-m telescopes from 2019 March to June
(Kim et al. 2011JKAS...44...81K 2011JKAS...44...81K). All of the 100 sources were observed
in the SiO 1-0, 2-1, and H2CO 212-111 transitions at
43.42376GHz, 86.84696GHz, and 140.83950GHz, respectively. And among
the sample, 41 targets were also observed in the SiO 3-2 transition at
130.26861GHz.
The observations were reduced with class reduction package
(http://www.iram.fr/IRAMFR/GILDAS). A linear baseline was removed from
each spectrum. The typical rms noise levels of the main-beam
brightness temperature scale are about 20mK for the SiO lines and 40mK
for the H2CO line at the velocity resolution of about 1km/s.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 156 100 The properties of the H2CO 212-111 line
table3.dat 93 34 The properties of the SiO 1-0 and 2-1 lines
emitted from corresponding sources
table4.dat 50 8 The properties of the SiO 3-2 line emitted from
corresponding sources
table5.dat 79 34 The column densities and abundances of the SiO
molecules estimated from the flux densities of
the SiO 1-0, 2-1, and 3-2 lines and the
excitation temperature is assumed to be 10K
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See also:
J/ApJS/208/14 : BGPS. IX. Data release 2. (Ginsburg+, 2013)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Source name (BGPS NNNN) from the BGPS
v2.1 data (Ginsburg et al.
2013ApJS..208...14G 2013ApJS..208...14G, Cat. J/ApJS/208/14)
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 34 F5.2 arcsec DEs Declination (J2000)
36- 41 F6.2 km/s VlsrNH31 ? NH3 line central velocity
(1st component) (1)
43- 46 F4.2 km/s e_VlsrNH31 ? Error on VlsrNH31
48- 53 F6.2 km/s VlsrNH32 ? NH3 line central velocity
(2nd component) (1)
55- 58 F4.2 km/s e_VlsrNH32 ? Error on VlsrNH32
60- 65 F6.2 km/s VlsrH2CO ? H2CO line central velocity
67- 70 F4.2 km/s e_VlsrH2CO ? Error on VlsrH2CO
72- 77 F6.3 K.km/s intTmbdv1 ? Velocity-integrated intensity
(1st component)
79- 83 F5.3 K.km/s e_intTmbdv1 ? Error on intTmbdv1
85- 90 F6.3 K.km/s intTmbdv2 ? Velocity-integrated intensity
(2nd component)
92- 96 F5.3 K.km/s e_intTmbdv2 ? Error on intTmbdv2
98- 102 F5.2 K Tmb1 ? Line peak at main beam temperature
(1st component)
104- 108 F5.2 K Tmb2 ? Line peak at main beam temperature
(2nd component)
110- 114 F5.2 km/s FWHM1 ? Full width at half-maximum
(1st component)
116- 119 F4.2 km/s e_FWHM1 ? Error on FWHM1
121- 124 F4.2 km/s FWHM2 ? Full width at half-maximum
(2nd component)
126- 129 F4.2 km/s e_FWHM2 ? Error on FWHM2
131- 138 F8.3 10-7Lsun LH2CO ? H2CO luminosity
140- 147 E8.3 cm-2 NH2CO ? H2CO column density
149- 156 E8.3 --- XH2CO ? H2CO abundance
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Note (1): In most targets, the line profiles are Gaussian. The line profiles of
10 sources show two velocity components. Four of them have two
emission components probably due to the line-of-sight effect since
the two emission components are resolved. The other six sources have
an absorption component as well as an emission component.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Source name (BGPS NNNN) from the BGPS
v2.1 data (Ginsburg et al.
2013ApJS..208...14G 2013ApJS..208...14G,
Cat. J/ApJS/208/14)
11- 16 F6.2 km/s Vlsr1-0 ? SiO 1-0 line central velocity
18- 21 F4.2 km/s e_Vlsr1-0 ? Error on Vlsr1-0
23- 27 F5.3 K.km/s intTmbdv1-0 ? Velocity-integrated intensity for the
SiO 1-0 line
29- 33 F5.3 K.km/s e_intTmbdv1-0 ? Error on intTmbdv1-0
35- 39 F5.3 K Tmb1-0 ? Line peak at main beam temperature
for the SiO 1-0 line
41- 44 F4.1 km/s FWZP1-0 ? Full width at zero power for the SiO
1-0 line
46- 51 F6.2 10-7Lsun LSiO1-0 ? SiO 1-0 line luminosity
53- 58 F6.2 km/s Vlsr2-1 ? SiO 2-1 line central velocity
60- 63 F4.2 km/s e_Vlsr2-1 ? Error on Vlsr2-1
65- 69 F5.3 K.km/s intTmbdv2-1 ? Velocity-integrated intensity for the
SiO 2-1 line
71- 75 F5.3 K.km/s e_intTmbdv2-1 ? Error on intTmbdv2-1
77- 81 F5.3 K Tmb2-1 ? Line peak at main beam temperature
for the SiO 2-1 line
83- 86 F4.1 km/s FWZP2-1 ? Full width at zero power for the SiO
2-1 line
88- 93 F6.2 10-7Lsun LSiO2-1 ? SiO 2-1 line luminosity
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Source name (BGPS NNNN) from the BGPS v2.1
data (Ginsburg et al. 2013ApJS..208...14G 2013ApJS..208...14G,
Cat. J/ApJS/208/14)
11- 16 F6.2 km/s Vlsr SiO 3-2 line central velocity
18- 21 F4.2 km/s e_Vlsr Error on Vlsr
23- 27 F5.3 K.km/s intTmbdv Velocity-integrated intensity for the SiO
3-2 line
29- 33 F5.3 K.km/s e_intTmbdv Error on intTmbdv
35- 39 F5.3 K Tmb Line peak at main beam temperature for the
SiO 3-2 line
41- 44 F4.1 km/s FWZP Full width at zero power for the SiO 3-2
line
46- 50 F5.2 10-7Lsun LSiO3-2 SiO 3-2 luminosity
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Source name (BGPS NNNN) from the BGPS v2.1
data (Ginsburg et al. 2013ApJS..208...14G 2013ApJS..208...14G,
Cat. J/ApJS/208/14)
11- 16 F6.1 Msun Mass Clump mass
18- 25 E8.3 cm-2 NH2 H2 column density
27- 34 E8.3 cm-2 NSiO1-0 ? SiO 1-0 column density
36- 43 E8.3 --- XSiO1-0 ? SiO 1-0 abundance
45- 52 E8.3 cm-2 NSiO2-1 ? SiO 2-1 column density
54- 61 E8.3 --- XSiO2-1 ? SiO 2-1 abundance
63- 70 E8.3 cm-2 NSiO3-2 ? SiO 3-2 column density
72- 79 E8.3 --- XSiO3-2 ? SiO 3-2 abundance
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 13-Sep-2023