J/A+A/620/A163 Cores in California molecular cloud (Zhang+, 2018)
Physical properties and chemical composition of the cores in the California
molecular cloud.
Zhang G.-Y., Xu J.-L., Vasyunin A.I., Semenov D.A., Wang J.-J., Dib S.,
Liu T., Liu S.-Y., Zhang C.-P., Liu X.-L., Wang K., Li D., Wu Z.-Z.,
Yuan J.-H., Li D.-L., Gao Y.
<Astron. Astrophys. 620, A163 (2018)>
=2018A&A...620A.163Z 2018A&A...620A.163Z (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Abundances ; Spectroscopy
Keywords: stars: formation - ISM: abundances - astrochemistry -
dust, extinction - ISM: molecules
Abstract:
We extracted 300 cores, of which 33 are protostellar and 267 are
starless cores. About 51% (137 of 267) of the starless cores are
prestellar cores. Three cores have the potential to evolve into
high-mass stars. The prestellar core mass function (CMF) can be well
fit by a log-normal form. The high-mass end of the prestellar CMF
shows a power-law form with an index α=-0.9±0.1 that is
shallower than that of the Galactic field stellar mass function.
Combining the mass transformation efficiency (ε) from the
prestellar core to the star of 15±1% and the core formation
efficiency (CFE) of 5.5%, we suggest an overall star formation
efficiency of about 1% in the CMC. In the single-pointing observations
with the IRAM 30m telescope, we find that 6 cores show blue-skewed
profile, while 4 cores show red-skewed profile. [HCO+]/[HNC] and
[HCO+]/[N2H+] in protostellar cores are higher than those in
prestellar cores; this can be used as chemical clocks. The best-fit
chemical age of the cores with line observations is ∼50000 years.
Description:
The Herschel data include PACS 70 and 160um (Poglitsch et al.,
2010A&A...518L...2P 2010A&A...518L...2P) and SPIRE 250, 350, and 500um (Griffin et al.,
2010A&A...518L...3G 2010A&A...518L...3G) imaging for the CMC (Harvey et al.,
2013ApJ...764..133H 2013ApJ...764..133H, Cat. J/ApJ/764/133). We used the Harvey et al.
(2013ApJ...764..133H 2013ApJ...764..133H, Cat. J/ApJ/764/133) version instead of the
current HSA pipeline products, see Harvey et al. (2013ApJ...764..133H 2013ApJ...764..133H,
Cat. J/ApJ/764/133). We made a high-resolution (18.2") H2 column
density map with with Herschel four-band emission from 160 to 500um.
Using this map, we extracted a complete core sample with the
fellwalker algorithm. Single-pointing observations at 30 positions
near 90GHz were carried out in April 2014 using the IRAM 30m telescope
on Pico Veleta, Spain. The frequency coverage includes the ground
rotational (1-0) transition of H13CO+, HN13C, C2H, HCN,
HCO+, HNC, N2H, C18O, and 13CO. The single-pixel heterodyne
receiver of the Eight MIxer Receiver (EMIR) with a band-width of 16GHz
in two orthogonal polarizations was employed to simultaneously observe
these nine lines. The fast Fourier transform spectrometer
(FTS)backends were set to 200kHz (about 0.65km/s at 90GHz) resolution.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
cores.dat 86 300 Parameters of 300 cores obtained from the
Herschel H2 column density map (table 3)
table1.dat 88 30 IRAM 30m observed positions
h13cop.dat 62 30 Properties of H13CO+(1-0) (table 4)
hn13c.dat 62 30 Properties of HN13C (1-0) (table 4)
n2hp.dat 69 30 Properties of N2H+ (1-0) (table 4)
c2h.dat 70 30 Properties of C2H (1-0) (table 4)
hcn.dat 70 30 Properties of HCN (1-0) (table 4)
hcop.dat 70 30 Properties of HCO+ (1-0) (table 4)
hnc.dat 70 30 Properties of HNC (1-0) (table 4)
c18o.dat 58 30 Properties of C18O (1-0) (table 4)
13co.dat 59 30 Properties of 13CO (1-0) (table 4)
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See also:
J/ApJ/764/133 : Auriga-California giant molecular cloud (Harvey+, 2013)
J/ApJ/786/37 : Auriga-California molecular cloud (Broekhoven-Fiene+, 2014)
J/A+A/606/A100 : YSOs in California Molecular Cloud (Lada+, 2017)
Byte-by-byte Description of file: cores.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Core Core number (CMCHerschel-NNN)
17- 18 I2 h RAh Right ascension (J2000.0) (1)
20- 21 I2 min RAm Right ascension (J2000.0)
23- 28 F6.3 s RAs Right ascension (J2000.0)
30 A1 --- DE- Declination sign (J2000.0) (1)
31- 32 I2 deg DEd Declination (J2000.0)
34- 35 I2 arcmin DEm Declination (J2000.0)
37- 41 F5.2 arcsec DEs Declination (J2000.0)
43- 47 F5.1 arcsec MajAxis Major axis of the ellipse (2)
49- 52 F4.1 arcsec MinAxis Minor axis of the ellipse
54- 58 F5.1 deg PA Position angle
60- 63 F4.2 pc Rad Core radius (3)
65- 68 F4.1 K Td Dust temperature (4)
70- 73 F4.1 cm-3 n(H2) Number density (5)
75- 78 F4.1 Msun M Core mass
80- 82 F3.1 Msun M(BE) Critical Bonnor-Ebert mass
84- 86 A3 --- Type Core type (6)
--------------------------------------------------------------------------------
Note (1): Right ascension and declination are the center positions of the core
ellipse shape. The cores are sorted from north to south.
Note (2): The values of the axes of the ellipse are equal to the FWHMs of the
equivalent Gaussian.
Note (3): The core radius is deconvolved to remove the effect of the
telescope beam.
Note (4): The average dust temperature in core ellipse shape.
Note (5): The number density is calculated on the assumption that the core is
spherical.
Note (6): Core type as follows:
USL = gravitationally unbound starless core
PRE = bound prestellar core
PRO = protostellar core
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- No Observation number (CMC-NN)
7 A1 --- n_No [*] Note on No (1)
8- 9 I2 h RAh Single-pointing observation right ascension
(J2000.0)
11- 12 I2 min RAm Single-pointing observation right ascension
(J2000.0)
14- 19 F6.3 s RAs Single-pointing observation right ascension
(J2000.0)
21 A1 --- DE- Single-pointing observation declination sign
(J2000.0)
22- 23 I2 deg DEd Single-pointing observation declination
(J2000.0)
25- 26 I2 arcmin DEm Single-pointing observation declination
(J2000.0)
28- 32 F5.2 arcsec DEs Single-pointing observation declination
(J2000.0)
34- 37 F4.1 K Td Dust average temperature in one beam
(29", IRAM 30m|86GHz)
39- 42 F4.1 10+21cm-2 SH2 H2 average column density in one beam
({SIGMA}H2)
44- 47 F4.2 pc R ? Radius
49- 52 F4.1 10+5cm-3 n(H2) ? Number density
54- 57 F4.1 Msun M ? Herschel core mass
59- 61 F3.1 Msun MV ? Virial mass
63- 65 F3.1 Msun M(BE) ? Critical Bonnor-Ebert mass
67- 72 A6 --- Type Core type (2)
74- 88 A15 --- Core Core number (CMCHerschel-NNN)
-------------------------------------------------------------------------------
Note (1): CMC-2 is galaxy 3C 111.
Note (2): Core type as follows:
PRE = gravitationally bound prestellar core
PRO = protostellar core
REF = reference position that is offset from the cores
Galaxy = galaxy
-------------------------------------------------------------------------------
Byte-by-byte Description of file: h13cop.dat hn13c.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- No Observation number (CMC-NN)
8- 11 F4.2 K Tmb ? Corrected main-beam temperature
13- 16 F4.2 K e_Tmb ? rms uncertainty on Tmb
18- 21 F4.2 K.km/s I ? Integrated main-beam temperature
23- 26 F4.2 K.km/s e_I ? rms uncertainty on I
28- 31 F4.2 km/s FWHM ? Full width at half-maximum of the
Gaussian fitting profile
33- 36 F4.2 km/s e_FWHM ? rms uncertainty on FWHM
38- 42 F5.2 km/s Vlsr ? Local standard of rest velocity
44- 47 F4.2 km/s e_Vlsr ? rms uncertainty on Vlsr
49- 52 F4.2 --- depth ? Optical depth (1)
54- 57 F4.2 10+12cm-2 N ? Column density
59- 62 F4.2 10-11 X ? Abundance
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Note (1): We assumed a constant abundance ratio of 50 for [C/13C] in the CMC.
The optical depths of H13CO+ and HCO+ and HN13C and HNC were obtained
by comparing the measured brightness temperatures.
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Byte-by-byte Description of file: n2hp.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- No Observation number (CMC-NN)
8- 11 F4.2 K Tmb ? Corrected main-beam temperature
13- 16 F4.2 K e_Tmb ? rms uncertainty on Tmb
18- 21 F4.2 K.km/s I ? Integrated main-beam temperature
23- 26 F4.2 K.km/s e_I ? rms uncertainty on I
28- 31 F4.2 km/s FWHM ? Full width at half-maximum of the
Gaussian fitting profile
33- 37 F5.2 km/s e_FWHM ? rms uncertainty on FWHM
39- 44 F6.2 km/s Vlsr ? Local standard of rest velocity
46- 49 F4.2 km/s e_Vlsr ? rms uncertainty on Vlsr
51- 54 F4.2 --- depth ? Optical depth (1)
56- 59 F4.2 --- e_depth ? rms uncertainty on depth (1)
61- 64 F4.2 10+13cm-2 N ? Column density (1)
66- 69 F4.2 10-10 X ? Abundance
--------------------------------------------------------------------------------
Note (1): Optical depth and column density for N2H+ are estimated by its
component JF1F=(101-012).
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Byte-by-byte Description of file: c2h.dat hcn.dat hcop.dat hnc.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- No Observation number (CMC-NN)
8- 11 F4.2 K Tmb ? Corrected main-beam temperature
13- 16 F4.2 K e_Tmb ? rms uncertainty on Tmb
18- 21 F4.2 K.km/s I ? Integrated main-beam temperature
23- 26 F4.2 K.km/s e_I ? rms uncertainty on I
28- 31 F4.2 km/s FWHM ? Full width at half-maximum of the
Gaussian fitting profile
33- 36 F4.2 km/s e_FWHM ? rms uncertainty on FWHM
38- 42 F5.2 km/s Vlsr ? Local standard of rest velocity
44- 47 F4.2 km/s e_Vlsr ? rms uncertainty on Vlsr
49- 53 F5.2 --- depth ? Optical depth (1)
55- 59 F5.2 --- e_depth ? rms uncertainty on depth
61- 64 F4.2 10+14cm-2 N ? Column density (1)
66- 70 F5.2 10-9 X ? Abundance
--------------------------------------------------------------------------------
Note (1): Optical depth for C2H is estimated by its main component
JF=(3/2,2-1/2,1) with the HFS method in the CLASS software. Column density
is also estimated by its main component.
Optical depth and column density for HCN are estimated by its main component
JF=(12-01).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: c18o.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- No Observation number (CMC-NN)
8- 11 F4.2 K Tmb ? Corrected main-beam temperature
13- 16 F4.2 K e_Tmb ? rms uncertainty on Tmb
18- 21 F4.2 K.km/s I ? Integrated main-beam temperature
23- 26 F4.2 K.km/s e_I ? rms uncertainty on I
28- 31 F4.2 km/s FWHM ? Full width at half-maximum of the
Gaussian fitting profile
33- 36 F4.2 km/s e_FWHM ? rms uncertainty on FWHM
38- 42 F5.2 km/s Vlsr ? Local standard of rest velocity
44- 47 F4.2 km/s e_Vlsr ? rms uncertainty on Vlsr
49- 52 F4.2 10+15cm-2 N ? Column density
54- 58 F5.2 10-8 X ? Abundance
--------------------------------------------------------------------------------
Byte-by-byte Description of file: 13co.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- No Observation number (CMC-NN)
8- 12 F5.2 K Tmb Corrected main-beam temperature
14- 17 F4.2 K e_Tmb rms uncertainty on Tmb
19- 23 F5.2 K.km/s I Integrated main-beam temperature
25- 28 F4.2 K.km/s e_I rms uncertainty on I
30- 33 F4.2 km/s FWHM Full width at half-maximum of the
Gaussian fitting profile
35- 38 F4.2 km/s e_FWHM rms uncertainty on FWHM
40- 44 F5.2 km/s Vlsr Local standard of rest velocity
46- 49 F4.2 km/s e_Vlsr rms uncertainty on Vlsr
51- 54 F4.2 10+16cm-2 N Column density
56- 59 F4.2 10-6 X Abundance
--------------------------------------------------------------------------------
Acknowledgements:
Guoyin Zhang, zgyin(at)nao.cas.cn
(End) Guoyin Zhang [NAOC, China], Patricia Vannier [CDS] 05-Nov-2018