temden task problem

Guest wrote on Feb 14, 2006

Hello,

I have a problem with the iraf task temden in stsdas.analysis.nebular. The
density calculation works fine but the temperature calculation always fails
after 2 iterations, even after trying it with carbon I, sulfur II and nitrogen
II. Typical values used are

temperature
flxratio=1 to 200
transit=default
assume=5000 to 8000

all of these are valid entries. What can I do?

Thanks
Andrew

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Guest wrote on Feb 14, 2006

Hi Andrew,

Sorry for taking so long to reply... I am the developer of the Nebular package and I'd like to help if I can. I will need a little more to go on, though because the examples I try seem to work for me. If you are just starting to use the temden task, may I suggest that you first use ionic to get an idea of what line emissivities to expect. Then try reproducing the result with temden.

For example, try

cl> ionic sulfur 2 temper=10000., dens=1000.

The result will give volume emissivities for a large number of lines, but the relevant ones are:

6730.78 (2->1): 2.459E-20
6716.42 (3->1): 2.157e-20
4076.35 (4->1): 1.522e-21
4068.60 (5->1): 4.153e-21

Taking the ratio of the emissivities from the line pair near 6725 to that for the line pair near 4072 gives 7.6487. Now plugging that into the temden task:

cl> temden temperature 7.6487 atom=sulfur spec=2 assume=1000

Temperature ratio S II: I(6725)/I(4072) = 7.6487
Temperature = 10000.2 K

Then if you try ratios near that value (e.g., 10.0, 6.0) you will see that you get convergent results. Where, you may ask, do you find out what ratios to use? Try the temden help page, Table 2 (for temperatures).

Hope this helps. If there are specific examples that should work but do not, please post a reply.

Regards,
Dick Shaw

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Last post on Feb 14, 2006