J/ApJS/152/81 CO survey toward starless cores (Park+, 2004)
A CO survey toward starless cores.
Park Y.-S., Lee C.W., Myers P.C.
<Astrophys. J. Suppl. Ser., 152, 81-96 (2004)>
=2004ApJS..152...81P 2004ApJS..152...81P
ADC_Keywords: Interstellar medium ; Surveys ; Radio lines
Keywords: ISM: clouds - ISM: molecules - radiative transfer - radio lines: ISM -
surveys
Abstract:
A CO survey is undertaken toward about 80% of the starless cores in
the Lee & Myers catalog that can be observed in the northern
hemisphere to investigate their general observational properties such
as line width and intensity, from which one can deduce their
environmental physical conditions. The peak 12CO intensity implies a
kinetic temperature close to 10K, as is already known, but for some of
the cores the kinetic temperature is much higher than 10K, suggesting
either that they are not really starless or that they are externally
heated. We derive the ratios of peak intensities and line widths for
the pairs of 12CO and 13CO lines and find a value of ∼1.7 for
both. The linear correlations between them are most likely to be due
to clumpy structure. These data are also compared with data sets of CS
2-1 and N2H+ 1-0 lines tracing high-density regions. It is
found that the peak intensity and line width of 13CO are roughly
correlated with those of CS, suggesting that the outer envelope is
kinematically related to the inner dense core. Confirming that the
12CO lines seldom exhibit deep self-reversal features, whereas this
is not unusual for the CS lines, we propose a heuristic model where
the outer part is clumpy, but the inner part has a rather smooth
density profile, with a uniform temperature and mean density
decreasing outward. We apply three-dimensional radiative transfer
calculations to this simple model, demonstrating that the essential
observational features of the starless cores are successfully
reproduced.
Description:
We carried out observations in 12CO and 13CO J=1-0 transitions
toward a fraction of starless cores cataloged in Lee & Myers (1999,
Cat. J/ApJS/123/233) between 1998 December and 1999 February, using
the 14m telescope at Taeduk Radio Astronomy Observatory (TRAO) in
Korea.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 56 178 Line parameters of 178 starless cores
--------------------------------------------------------------------------------
See also:
J/ApJS/123/233 : Catalog of Optically selected cores (Lee+, 1999)
J/ApJ/526/788 : Survey of infall motions toward starless cores (Lee+, 1999)
J/ApJS/153/523 : Infall motions toward starless cores. III. (Lee+, 2004)
J/ApJ/664/928 : Starless cores in HCN(J=1-0) (Sohn+ 2007)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- [LM99] Source name
10- 11 I2 h RAh Hour of Right Ascension (J2000)
13- 14 I2 min RAm Minute of Right Ascension (J2000)
16- 19 F4.1 s RAs Second of Right Ascension (J2000)
21 A1 --- DE- Sign of the Declination (J2000)
22- 23 I2 deg DEd Degree of Declination (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination (J2000)
28- 29 I2 arcsec DEs Arcsecond of Declination (J2000)
31- 34 F4.2 K 12CO-T ? The 12CO temperature (115.271GHz)
35 A1 --- f_12CO-T [*] Flag on 12CO-T (1)
37- 40 F4.2 km/s 12CO-DelV ? The 12CO line width
42- 45 F4.2 K 13CO-T The 13CO temperature (110.201GHz)
47- 50 F4.2 km/s 13CO-DelV The 13CO line width
52- 56 F5.2 K.km/s 13CO-F Integrated 13CO line flux
--------------------------------------------------------------------------------
Note (1):
* = line parameters can not be derived due to the telluric 12CO.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 28-Sep-2010