J/ApJ/820/37 HCO+ and HCN obs. toward Planck Galactic Cold Clumps (Yuan+, 2016)
Dense gas in molecular cores associated with Planck Galactic Cold Clumps.
Yuan J., Wu Y., Liu T., Zhang T., Li J.Z., Liu H.-L., Meng F., Chen P.,
Hu R., Wang K.
<Astrophys. J., 820, 37 (2016)>
=2016ApJ...820...37Y 2016ApJ...820...37Y (SIMBAD/NED BibCode)
ADC_Keywords: Radio lines ; Interstellar medium
Keywords: ISM: abundances; ISM: clouds; ISM: kinematics and dynamics;
ISM: molecules; stars: formation
Abstract:
We present the first survey of dense gas toward Planck Galactic Cold
Clumps (PGCCs). Observations in the J=1-0 transitions of HCO+ and
HCN toward 621 molecular cores associated with PGCCs were performed
using the Purple Mountain Observatory's 13.7m telescope. Among them,
250 sources were detected, including 230 cores detected in HCO+ and
158 in HCN. Spectra of the J=1-0 transitions from 12CO, 13CO, and
C18O at the centers of the 250 cores were extracted from previous
mapping observations to construct a multi-line data set. The
significantly low detection rate of asymmetric double-peaked profiles,
together with the good consistency among central velocities of CO,
HCO+, and HCN spectra, suggests that the CO-selected Planck cores
are more quiescent than classical star-forming regions. The small
difference between line widths of C18O and HCN indicates that the
inner regions of CO-selected Planck cores are no more turbulent than
the exterior. The velocity-integrated intensities and abundances of
HCO+ are positively correlated with those of HCN, suggesting that
these two species are well coupled and chemically connected. The
detected abundances of both HCO+ and HCN are significantly lower
than values in other low- to high-mass star-forming regions. The low
abundances may be due to beam dilution. On the basis of an inspection
of the parameters given in the PGCC catalog, we suggest that there may
be about 1000 PGCC objects that have a sufficient reservoir of dense
gas to form stars.
Description:
More than 600 Planck cold clumps have been mapped in the J=1-0
transitions of 12CO, 13CO, and C18O. A 22'x22' region for each
clump was mapped with a spatial resolution of about 52". Details about
the mapping observations are provided by Liu et al. (2012, J/ApJS/202/4)
and Meng et al. (2013, J/ApJS/209/37).
Single-pointing observations of the CO-selected cores in HCO+ J=1-0
(89.189GHz) and HCN J=1-0 (88.632GHz) were carried out using the 13.7m
telescope of the Purple Mountain Observatory (PMO) with the
position-switch mode from 2013 June to July and from 2014 May to June.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 146 254 Observational parameters of HCO+ and HCN
table2.dat 135 254 Derived parameters
--------------------------------------------------------------------------------
See also:
VIII/88 : Planck Early Release Compact Source Catalogue (Planck, 2011)
J/A+A/584/A93 : Galactic cold cores. V. Dust opacity (Juvela+, 2015)
J/A+A/569/A125 : Spiral structure of the Milky Way (Hou+, 2014)
J/A+A/563/A97 : IRAM 30m reduced spectra of 59 sources (Gerner+, 2014)
J/ApJS/209/37 : Planck cold clumps in 12CO, 13CO and C18O (Meng+, 2013)
J/ApJS/202/4 : Planck cold clumps survey in the Orion complex (Liu+, 2012)
J/ApJ/756/76 : Planck cold dust clumps CO survey (Wu+, 2012)
J/ApJ/756/60 : A 3mm line survey in 37 IR dark clouds (Sanhueza+, 2012)
J/A+A/527/A88 : Chemistry in infrared dark clouds (Vasyunina+, 2011)
J/A+AS/133/29 : Molecular line survey towards UC HII (Hatchell+ 1998)
http://www.ism-spp.de/ : ISM program home page
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- PLCKECC Planck Early Cold Core identifier
(GLLL.ll+BB.bb)
14- 15 A2 --- ID Source identifier (aN)
17- 18 I2 h RAh ? Hour of Right Ascension (J2000)
20- 21 I2 min RAm Minute of Right Ascension (J2000)
23- 27 F5.2 s RAs Second of Right Ascension (J2000)
29- 29 A1 --- DE- Sign of the Declination (J2000)
30- 31 I2 deg DEd Degree of Declination (J2000)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000)
36- 39 F4.1 arcsec DEs Arcsecond of Declination (J2000)
41- 44 F4.2 K HCO+rms ? HCO+ spectrum root-mean-square
46- 49 F4.2 K HCO+Tp ? HCO+ spectrum peak intensity
51- 55 F5.2 K e_HCO+Tp ? Error in HCO+Tp
57- 61 F5.2 K.km/s HCO+W ? HCO+ spectrum area
63- 66 F4.2 K.km/s e_HCO+W ? Error in HCO+W
68- 73 F6.2 km/s HCO+V [-53/25]? HCO+ local standard of rest
velocity
75- 78 F4.2 km/s e_HCO+V [0.01/0.6]? Error in HCO+V
80- 83 F4.2 km/s HCO+FWHM [0.4/4.7]? HCO+ line width
85- 89 F5.2 km/s e_HCO+FWHM [0.03/25.5]? Error in HCO+FWHM
91- 94 F4.2 K HCNrms ? HCN spectrum root-mean-square
96- 99 F4.2 K HCNTp ? HCN spectrum peak intensity
101-104 F4.2 K e_HCNTp ? Error in HCNTp
106-109 F4.2 K.km/s HCNW ? HCO+ spectrum area
111-114 F4.2 K.km/s e_HCNW ? Error in HCNW
116-121 F6.2 km/s HCNV [-51/15]? HCN local standard of rest velocity
123-126 F4.2 km/s e_HCNV [0.02/0.4]? Error in HCNV
128-131 F4.2 km/s HCNFWHM [0.6/2.7]? HCO+ line width
133-136 F4.2 km/s e_HCNFWHM [0.01/1.6]? Error in HCNFWHM
138-141 F4.2 --- tau [0.1/3.2]? HCN spectrum main component
optical depth
143-146 F4.2 --- e_tau [0/1.9]? Error in tau
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- PLCKECC Planck Early Cold Core identifier
(GLLL.ll+BB.bb)
14- 15 A2 --- ID Source identifier (aN)
17- 21 F5.2 kpc RGal [7.6/18.7]? Galactocentric distance
23- 27 F5.2 kpc Dist [0.1/14.7]? Distance from the Sun
29- 32 F4.2 --- tau13CO [0.1/2.4] Optical depth of 13CO
34- 37 F4.2 --- tau18CO [0.04/0.7]? Optical depth of 18CO
39- 42 F4.2 --- tauHCO+ [0.05/4.1]? HCO+ optical depth of HCO+
44- 48 F5.2 K TexCO [7/35]? Excitation temperature of CO
50- 53 F4.2 K e_TexCO [0.1/2]? Error in TexCO
55- 59 F5.2 10+15cm-2 N13CO [3.7/56.7]? Column density of 13CO
61- 64 F4.2 10+15cm-2 e_N13CO [0.2/5]? Error in N13CO
66- 69 F4.2 10+15cm-2 N18CO [0.2/8.7]? Column density of 18CO
71- 74 F4.2 10+15cm-2 e_N18CO [0.07/2]? Error in N18CO
76- 80 F5.2 10+12cm-2 NHCO+ [0.07/24.2]? Column density of HCO+
82- 85 F4.2 10+12cm-2 e_NHCO+ [0.03/5]? Error in NHCO+
87- 91 F5.2 10+12cm-2 NHCN [0.2/16.2]? Column density of HCN
93- 97 F5.2 10+12cm-2 e_NHCN [0.1/15]? Error in NHCN
99-103 F5.2 10+12cm-2 NH2 [1.4/71]? Column density of H2
105-109 F5.2 10+12cm-2 e_NH2 [0.2/16]? Error in NH2
111-116 F6.2 10-11 XHCO+ [0.3/152.2]? Fractional abundance of HCO+
118-122 F5.2 10-11 e_XHCO+ [0.1/49]? Error in XHCO+
124-128 F5.2 10-11 XHCN [1.2/56]? Fractional abundance of HCN
130-135 F6.2 10-11 e_XHCN [0.4/194]? Error in XHCN
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 31-May-2016