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J/ApJS/63/821 Inner Galaxy Molecular clouds and cloud cores (Scoville+, 1987)
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Molecular clouds and cloud cores in the inner Galaxy
Scoville N.Z., Yun Min Su, Sanders D.B., Clemens D.P., Waller W.H.
<Astrophys. J. Suppl. Ser. 63, 821 (1987)>
=1987ApJS...63..821S
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ADC_Keywords: CO; Interstellar medium; H II regions
Keywords: galaxies: Milky Way - interstellar: molecules - nebulae:
H II regions
Abstract:
A compilation of CO emission regions and their measured parameters is
presented which represents a nearly complete accounting of the molecular
clouds in the first quadrant of the Galaxy. Emission regions associated
with radio H II regions have systematically brighter CO peaks that are a
factor of two to three times larger and have twice the mean velocity
dispersion as the general cloud population. Both the H II region clouds
and the hot core regions have a Galactic distribution characteristic of a
spiral arm population, whereas the colder clouds are much less confined
in Galactic azimuthal angle. Virial masses are obtained for the large
sample of clouds with assigned kinematic distances. The mean H2 density
for a GMC of diameter 40 pc is 180/cm. For these clouds, a linear
relationship is found between the H2 column density and the integrated CO
emission. The variation in the Z-dispersion of clouds as a function of
cloud mass suggests that more massive GMCs have smaller random velocities.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 109 1682 CO Clouds and Hot Cores
table2.dat 130 171 H II Region Clouds
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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- 4 I4 --- Num Cloud number
5 A1 --- Core ?Hot core designation (noted by letter).
7- 11 F5.2 deg GLON1 Galactic longitude at the position of peak
CO emission
13- 17 F5.2 deg GLAT1 Galactic latitude at the position of peak
CO emission
19- 21 I3 km/s VLSR LSR velocity at the position of peak
CO emission
23- 26 F4.1 K TCO CO temperatures at the position of peak
CO emission
28- 32 F5.2 deg GLON2 Centroid galactic longitude
34- 38 F5.2 deg GLAT2 Centroid galactic latitude
40- 44 F5.1 km/s Vel Centroid velocity
46- 49 F4.1 K Tmean Mean temperature for CO emission
51- 55 I5 --- Pnum Total number of (l, b, V) points
contained in cloud within 4 K boundary
57- 60 F4.1 kpc Distn ? Near kinematic distance
62- 65 F4.1 kpc Distf ? Far kinematic distance
67- 70 F4.1 kpc Rgal *? Galactic radius
72- 75 I4 pc DistZ Z distance corresponding to the cloud
centroid latitude
77- 80 F4.2 deg Melon1 *Maximum extent of the cloud in longitude,
length is expressed in degrees
82- 86 F5.1 pc Melon2 *Maximum extent of the cloud in longitude,
length is expressed in parsecs
88- 91 F4.2 deg Melat1 *Maximum extent of the cloud in latitude,
length is expressed in degrees
93- 97 F5.1 pc Melat2 *Maximum extent of the cloud in latitude,
length is expressed in parsecs
99- 103 F5.2 km/s sigma Velocity dispersion measured for points
above the 4 K or 8 K thresholds
105- 109 A5 --- Notes *Clouds for which the distance can be
resolved
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Note on Rgal:
Obtained from the (l,b,V) centroid using Clemens's (1985b) rotation curve
with R_0=8.5 kpc and {theta}_0=220 kms^1. In cases where the distance
ambiguity cannot be resolved from the Z-height or association with the 3
kpc or Cygnus arms (see paper), the near distance is adopted for the linear
sizes used in Dist2, Melon2, and Melat2.
Note on Melon1, Melon2:
The difference of the highest and lowest longitude points within the cloud.
The maximum extents are typically a factor of 1.36 larger than the
square-root areas (A1/2) given in table2.dat.
Note on Melat1, Melat2:
The difference between the highest and lowest latitudes.
Note on Notes:
Based on Z-height, proximity to the tangent point (i.e., less than 40% far
distances), and location in the 3 kpc or Cygnus arms. Any clouds not noted
have ambiguous distances.
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Region *H II region
20- 26 F7.1 Jy.kpc2 Lumr *H II region luminosity
28- 32 F5.2 deg GLON1 ?Galactic longitude at the position of peak
CO emission
34- 38 F5.2 deg GLAT1 ?Galactic latitude at the position of peak
CO emission
40- 42 I3 km/s VLSR ?LSR velocity at the position of peak
CO emission
44- 47 F4.1 K TCO ?CO temperatures at the position of peak
CO emission
49- 53 F5.2 deg GLON2 ?Centroid galactic longitude
55- 59 F5.2 deg GLAT2 ?Centroid galactic latitude
61- 63 I3 km/s Vel ?Centroid velocity
65- 68 F4.1 K Tmean ?Mean temperature for CO emission
70- 73 I4 --- Pnum *?Total number of (l,b,V) points
75- 78 F4.1 kpc Distn ?Near kinematic distance
80- 83 F4.1 kpc Distf ?Far kinematic distance
85- 87 F3.1 kpc Rgal *?Galactic radius obtained from the (l,b,V)
centroid of the CO emission
89- 92 F4.2 deg Mclat1 *?Mean chord length in galactic latitude
expressed in degrees
94- 96 I3 pc Mclat2 *?Mean chord length in galactic latitude
expressed in parsecs
98- 101 F4.2 deg Mclon1 *?Mean chord length in galactic longitude
expressed in degrees
103- 104 I2 pc Mclon2 *?Mean chord length in galactic longitude
expressed in parsecs
106- 108 I3 pc Root ?Square root of the area of the cloud
projected onto the plane of sky
110- 115 I6 --- LumCO *?CO luminosity (K km s^1pc^2) of the cloud
117- 119 F3.1 km/s sigma ?Velocity dispersion for data above the
threshold temperature
121- 123 F3.1 K Thtemp ?Threshold temperature defining the cloud
boundary in (l,b,V)-space
125- 130 A6 --- Notes *?Distance assignment
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Note on Region:
Specified by l, b, V_LSR of the radio recombination line from Downes et al.
(1980) and Lockman (1989).
Note on Lumr:
{lambda} = 6 cm radio luminosity of the HII region, S_Jyd^2_kpc, where d is
the kinematic distance (Distn and Distf). In cases where the distance
ambiguity is not resolved (see Notes), the near distance is adopted.
Note on Pnum:
Contained within the cloud boundary defined at the threshold temperature
T_c (Thtemp).
Note on Rgal:
Using Clemens (1985b) rotation curve with R_0=8.5 kpc and {theta}_0=220
kms^1.
Note on Mclat1, Mclat2:
Using kinematic distance for all latitudes included in the clouds
Note on Mclon1, Mclon2:
For all longitudes included in the cloud.
Note on LumCO:
The sum of the intergrated CO intensities along all lines of sight within
the cloud boundary times the pixel area for 3'x3'.
Note on Notes:
Based on Z-distance, proximity to the tangential point, or location in the
3 kpc or Cygnus arms.
References:
Clemens, D.P. 1985b, ApJ, 295, 422 =1985ApJ...295..422C
Downes, D., Wilson, T.L., Bieging J., and Wink, J. 1980, A+AS, 40, 379
=1980A&AS...40..379D
Lockman, F.J. 1989, ApJS, 71, 469 =1989ApJS...71..469L
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(End) Gail Schneider [SSDOO/ADC] 27-Nov-2000