J/ApJ/664/928 Starless cores in HCN(J=1-0) (Sohn+ 2007)
Probing inward motions in starless cores using the HCN(J = 1-0) hyperfine
transitions: a pointing survey toward central regions.
Sohn J., Lee C.W., Park Y.-S., Lee H.M., Myers P.C., Lee Y.
<Astrophys. J., 664, 928-941 (2007)>
=2007ApJ...664..928S 2007ApJ...664..928S
ADC_Keywords: Globules ; Interstellar medium ; Radio lines
Keywords: ISM: globules - ISM: kinematics and dynamics - ISM: molecules -
stars: formation
Abstract:
We have carried out a survey toward the central regions of 85 starless
cores in HCN(J=1-0) to study inward motions in the cores. Sixty-four
cores were detected with HCN lines. The infall asymmetry in the HCN
spectra is found to be more prevalent, and more prominent than in any
other previously used infall tracers such as CS(J=2-1), DCO+(J=2-1),
and N2H+(J=1-0). We have found a close relation between the
intensities of the HCN and N2H+ lines.
Description:
We have conducted single-pointing observations for 85 starless cores
in HCN(J=1-0) with the 13.7m telescope of the Taeduk Radio
Astronomical Observatory (TRAO) in Korea. Observations were carried
out during 2002 January, February, November, and December and 2003
January to May.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 138 85 The line parameters of the starless cores
observed in HCN and H13CN J=1-0 lines
table2.dat 37 68 Line asymmetry colors of starless cores
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Source name
10 A1 --- f_Name [a] double peaked sources (1)
12- 13 I2 h RAh Hour of Right Ascension (J2000) (2)
15- 16 I2 min RAm Minute of Right Ascension (J2000) (2)
18- 21 F4.1 s RAs Second of Right Ascension (J2000) (2)
23 A1 --- DE- Sign of the Declination (J2000)(2)
24- 25 I2 deg DEd Degree of Declination (J2000) (2)
27- 28 I2 arcmin DEm Arcminute of Declination (J2000) (2)
30- 31 I2 arcsec DEs Arcsecond of Declination (J2000) (2)
33 A1 --- l_T.HCN The 3σ limit flag on T.HCN
34- 39 F6.2 K T.HCN Antenna temperature of HCN J=1-0 (F=2-1)
41 A1 --- l_T.H13CN The 3σ limit flag on T.H13CN
42- 47 F6.2 K T.H13CN ? Antenna temperature of H13CN J=1-0
49- 53 F5.2 km/s V(F=0-1) ? Peak HCN J=1-0(F=0-1) intensity velocity
55- 58 F4.2 km/s e_V(F=0-1) ? Error in V(F=0-1)
60- 64 F5.2 km/s V(F=1-1) ? Peak HCN J=1-0(F=1-1) intensity velocity
66- 69 F4.2 km/s e_V(F=1-1) ? Error in V(F=1-1)
71- 75 F5.2 km/s V(F=2-1) ? Peak HCN J=1-0(F=2-1) intensity velocity
77- 80 F4.2 km/s e_V(F=2-1) ? Error in V(F=2-1)
82- 86 F5.2 km/s VN2H ? The N2H+ velocity (3)
88- 92 F5.2 km/s e_VN2H ? Error in VN2H
94- 97 F4.2 km/s W(N2H) ? The FWHM of N2H+ (3)
99-102 F4.2 km/s e_W(N2H) ? Error in d(N2H)
104-109 F6.3 --- d(F=0-1) ? Normalized HCN J=1-0(F=0-1) velocity
difference
111-114 F4.2 --- e_d(F=0-1) ? Error in d(F=0-1)
116-121 F6.3 --- d(F=1-1) ? Normalized HCN J=1-0(F=1-1) velocity
difference
123-126 F4.2 --- e_d(F=1-1) ? Error in d(F=1-1)
128-133 F6.3 --- d(F=2-1) ? Normalized HCN J=1-0(F=2-1) velocity
difference
135-138 F4.2 --- e_d(F=2-1) ? Error in d(F=2-1)
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Note (1): a = These sources have double peaks in HCN spectra whose
intensity ratios are close to 1.0 within error. The HCN peak
velocities for such sources were obtained by the Gaussian fit after
masking a fainter peak between two components. The δV values of
these sources are not used in our statistical analysis of δV.
Note (2): Coordinates observed toward the sources which are from the Lee &
Myers (1999, Cat. J/ApJS/123/233) catalog.
Note (3): Taken from Lee & Myers (1999, Cat. J/ApJS/123/233) by slightly
shifting them from the original values using the new frequency of
N2H+ J=1-0 taken from Lee, Myers & Tafalla (2001ApJS..136..703L 2001ApJS..136..703L).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Source name
10- 11 I2 --- d(VF=2-1) ? Normalized velocity difference line
asymmetry diagnostic for HCN(1-0)F=2-1 (1)
13- 14 I2 --- d(VCS2-1) ? Normalized velocity difference line
asymmetry diagnostic for HCN(1-0)CS(2-1) (1)
16- 17 I2 --- d(VCS3-2) ? Normalized velocity difference line
asymmetry diagnostic for HCN(1-0)CS(3-2) (1)
19- 20 I2 --- d(VDCO) ? Normalized velocity difference line
asymmetry diagnostic for HCN(1-0)DCO+(2-1) (1)
22- 23 I2 --- Tb/Tr(F=2-1) ? Blue to Red ratio line asymmetry diagnostic
for HCN(1-0)F=2-1 (1)
25- 26 I2 --- Tb/Tr(CS2-1) ? Blue to Red ratio line asymmetry diagnostic
for HCN(1-0)CS(2-1) (1)
28- 29 I2 --- Tb/Tr(CS3-2) ? Blue to Red ratio line asymmetry diagnostic
for HCN(1-0)CS(3-2) (1)
31- 32 I2 --- Tb/Tr(DCO) ? Blue to Red ratio line asymmetry diagnostic
for HCN(1-0)DCO+(2-1) (1)
34 I1 --- Tb/Tr(N2H) ? Blue to Red ratio line asymmetry diagnostic
for HCN(1-0)N2H+ (1)
36- 37 I2 --- Total Total color code
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Note (1): The δV value is flagged as follows:
1 = δV≤-5σ(δV)
0 = |δV|<5σ(δV)
-1 = δV≥-5σ(δV)
A good infall candidate should be given a number "1". In a similar way
the intensity ratio is also flagged with:
1 = Tb/Tr>1+σ(Tb/Tr),
0 = 1-σ(Tb/Tr)<Tb/Tr<1+σ(Tb/Tr),
-1 = Tb/Tr<1-σ(Tb/Tr),
where the values of Tb and Tr were obtained from Gaussian fits of blue
and red components of the profile. Again, a dense core flagged with 1
should be considered to be an infall candidate. The above criteria
used for selecting infall candidates are similar to those used by
LMT99 (J/ApJS/123/233) and LMP04 (J/ApJS/123/233), but have more data
from this HCN study.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 29-Aug-2009