J/ApJS/63/821 Inner Galaxy Molecular clouds and cloud cores (Scoville+, 1987)
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
ADC_Keywords: Carbon monoxide; 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 180cm-3. 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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 109 1682 CO Clouds and Hot Cores table2.dat 130 171 H II Region Clouds
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Num Cloud number 5 A1 --- Core ?Hot core designation (noted by letter). 7- 11 F5.2 deg GLONp Galactic longitude at the position of peak CO emission 13- 17 F5.2 deg GLATp 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 GLON Centroid galactic longitude 34- 38 F5.2 deg GLAT 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
Note on Rgal: Obtained from the (l,b,V) centroid using Clemens's (1985ApJ...295..422C) rotation curve with R0=8.5 kpc and θ0=220 km.s1. 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
Bytes Format Units Label Explanations
1- 18 A18 --- Region *H II region 20- 26 F7.1 Jy.kpc2 Lumr *H II region luminosity 28- 32 F5.2 deg GLONp ?Galactic longitude at the position of peak CO emission 34- 38 F5.2 deg GLATp ?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 GLON ?Centroid galactic longitude 55- 59 F5.2 deg GLAT ?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 K.km/s.pc-2 LumCO *?CO luminosity (K.km.s^-1^.pc^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
Note on Region: Specified by l, b, VLSR of the radio recombination line from Downes et al. (1980A&AS...40..379D) and Lockman (1989ApJS...71..469L). Note on Lumr: λ = 6 cm radio luminosity of the HII region, SJydkpc2, 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 Tc (Thtemp). Note on Rgal: Using Clemens (1985ApJ...295..422C) rotation curve with R0=8.5 kpc and θ0=220 km.s1. 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
(End) Gail Schneider [SSDOO/ADC] 27-Nov-2000
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