J/other/RAA/20.115 Molecular clumps CO, HCO and HCN data (Yang+, 2020)
In search of infall motion in molecular clumps.
II: HCO+ (1-0) and HCN (1-0) observations toward a sub-sample of infall
candidates.
Yang Y., Jiang Z.-B., Chen Z.-W., Zhang S.-B., Yu S.-L., Ao Y.-P.
<Res. Astron. Astrophys., 20, 115 (2020)>
=2020RAA....20..115Y 2020RAA....20..115Y (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interstellar medium ; Spectroscopy
Keywords: stars: formation - ISM: kinematics and dynamics - ISM: molecules -
radio lines: ISM
Abstract:
Gravitational accretion accumulates the original mass. This process is
crucial for us to understand the initial phases of star formation.
Using the specific infall profiles in optically thick and thin lines,
we searched the clumps with infall motion from the Milky Way Imaging
Scroll Painting (MWISP) CO data in previous work. In this study, we
selected 133 sources as a sub-sample for further research and
identification. The excitation temperatures of these sources are
between 7.0 and 38.5K, while the H2 column densities are between
1021 and 1023cm-2. We have observed optically thick lines
HCO+(1-0) and HCN(1-0) using the DLH 13.7-m telescope, and found 56
sources with a blue profile and no red profile in these two lines,
which are likely to have infall motions, with a detection rate of 42%.
This suggests that using CO data to restrict the sample can
effectively improve the infall detection rate. Among these confirmed
infall sources are 43 associated with Class 0/I young stellar objects
(YSOs), and 13 which are not. These 13 sources are probably associated
with the sources in the earlier evolutionary stage. In comparison, the
confirmed sources that are associated with Class 0/I YSOs have higher
excitation temperatures and column densities, while the other sources
are colder and have lower column densities. Most infall velocities of
the sources that we confirmed are between 10-1 to 100km/s, which is
consistent with previous studies.
Description:
In the previous work (Jiang et al., 2020, in prep.), using the CO data
from the MWISP project, approximately 2200 candidates with infall
spectral characteristics were identified by machine search and manual
checking. We selected 133 sources of them with significant blue
profiles in 12CO, and C18O intensities >1K as a sub-sample for
further study. Using the DLH 13.7-m telescope, we carried out
observations of optically thick lines HCO+ (1-0) and HCN (1-0)
toward these sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 56 133 The derived clump parameters
tableb2.dat 95 133 The derived line parameters and profiles of sample
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Source Source name
13 A1 --- n_Source [+] Note on Source (1)
15- 16 I2 h RAh Right ascension (J2000)
18- 19 I2 min RAm Right ascension (J2000)
21- 24 F4.1 s RAs Right ascension (J2000)
26 A1 --- DE- Declination sign (J2000)
27- 28 I2 deg DEd Declination (J2000)
30- 31 I2 arcmin DEm Declination (J2000)
33- 34 I2 arcsec DEs Declination (J2000)
36- 40 F5.1 km/s VLSR LSR velocity
42- 45 F4.2 kpc Dist Heliocentric distance
47- 50 F4.1 K Tex(12CO) Excitation temperature
52- 56 F5.2 [cm-2] log(N(H2)) H2 column density
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Note (1): Note as follows:
+ = Source are associated with Class 0/I YSOs
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Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Source Source name
14- 19 F6.2 km/s VthickHCO+(1-0) ?=- Peak velocity of HCO+(1-0)
21- 24 F4.2 km/s e_VthickHCO+(1-0) ? rms uncertainty on VthickHCO+(1-0)
27- 32 F6.2 km/s VthickHCN(1-0) ?=- Peak velocity of HCN(1-0)
34- 37 F4.2 km/s e_VthickHCN(1-0) ? rms uncertainty on VthickHCN(1-0)
40- 45 F6.2 km/s VthinC18O(1-0) Peak velocity of C18O(1-0)
47- 50 F4.2 km/s e_VthinC18O(1-0) rms uncertainty on VthiniC18O(1-0)
52- 56 F5.2 --- deltaVC18O(1-0) FWHM of C18O(1-0)
58- 61 F4.2 --- e_deltaVC18O(1-0) rms uncertainty on deltaVC18O(1-0)
64- 68 F5.2 --- deltaVHCO+(1-0) ?=- Asymmetry of HCO+(1-0)
70- 73 F4.2 --- e_deltaVHCO+(1-0) ? rms uncertainty on deltaVHCO+(1-0)
76- 80 F5.2 --- deltaVHCN(1-0) ?=- Asymmetry of HCN(1-0)
82- 85 F4.2 --- e_deltaVHCN(1-0) ? rms uncertainty on deltaVHCN(1-0)
88- 95 A8 --- Profile Profile of HCO+(1-0) and HCN(1-0) (1)
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Note (1): B denotes blue profile, R denotes red profile, and N denotes either
non-detection or detection with a single symmetric peak.
a indicates a source which is associated with the ATLASGAL compact sources,
b indicates a source which is associated with the ATLASGAL cold high-mass
clumps and g indicates a source which is associated with the BGPS sources.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Aug-2021