Content-type: text/html Manpage of colden

colden

Section: User Commands (1)
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NAME

colden - Calculates column densities for linear molecules  

PERSON RESPONSIBLE

mchw  

CATEGORIES

map analysis  

DESCRIPTION

COLDEN is a MIRIAD task to calculate column densities. The maps must have the same dimensions. The two images are compared on a pixel by pixel basis, within a user defined region.  

PARAMETERS

method
Three possibilities:(1) Give one optically thin transition and the kinetic temperature (Assumes tau=0). Enter in1, in2, J1, B1, mu, scale1.(2) Give two optically thin transitions with different J.The calculation will assume LTE, calculate col. den. as in (1), and fit to the best kinetic temperature and total column density. Enter in1,J1,b1,scale1, in2,J2,scale2, and mu (b1=b2). (3) Give one optically thick and one less thick transition. Assumes Tex(thick)=Tex(thin) and calculates optical depth of less thick transition. Col. den. ensue. Enter in1,J1,b1,scale1, in2,b2,scale2, and mu (J1=J2). Default=1.
in1
The first input image contains the most abundant isotope (e.g. 12CO). The first plane must contain the integrated intensity of the line (K-km/s) for methods 1 and 2, and the peak temperature of the line (K) for method 3. No default
in2
For method 1, give the kinetic temperature in the first plane. For method 2, this image contains the integrated intensity of the second transition. For method 3, the image contains the less abundant (thin) isotope (e.g. 13CO). It contains at least three planes: the peak temperature of the line, its center position, and its FWHM width. Use the output from program Gaufit. No default
region
Region to select data to compare from....(not implemented)
out
Output image. It consists of 7 planes; the meaning of the first 3 depend on the method used. (1) the first two planes are blank, the third is the col. den. of the upper level of the transition. (2) the first is the kinetic temperature, the next two the column densities of the upper levels of each transition. (3) the first is the optical depth of the less abundant isotope, the second is the excitation temperature of the abundant isotope, and the third is the column density of the upper level of the line analyzed. The remaining four planes are: the estimated total column density of the molecule, the column density of H2 inferred, the mass in each pixel, and a last plane in which every unmasked pixel is set to 1.
cut
Two values. Cutoff applied to data (i.e. column densities will not be calculate for input parameter values less than cutoff). Default=0.1 K, 0.1 km/s. There also is a cutoff for values of temp > 1000 K, v > 100 km/s. Additionally, values for column densities greater than 1.0e+27 are not written to the output file.
b1
Value of B (in GHz) for the optically thick isotope.Default=57.6 (12CO).
b2
Value of B (in GHz) for the optically thin isotope.Default=55.1 (13CO).
j1
the rotational number of the upper level. Default J=1
j2
the rotational number of the upper level. Default J=2
mu
The dipole moment of the molecule (in Debye). Default mu=0.112 (CO)
scale1
A constant that will multiply the peak temperatures in in1. Default=1.0
scale2
A constant that will multiply the peak temperatures in in2. Default=1.0
abund
The abundance of the less abundant isotope, relative to H2. THis will be used to compute the H2 column density. Default=2.0e-06 (appropriate for 13CO in dark clouds).
dist
THe distance of the source (in pc). It will be used to compute the mass in each pixel from the H2 column density. Default: 500 pc.
options
taulog: the optical depths are written as logs collog: the column densities are written as logs maslog: the masses are written as logs


 

Index

NAME
PERSON RESPONSIBLE
CATEGORIES
DESCRIPTION
PARAMETERS

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Time: 18:35:38 GMT, July 05, 2011