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View Full Version : Hydrogen Fluoride as a tracer of Molecular Hydrogen



trinitree88
2010-Jul-14, 08:59 PM
It's not easy to find molecular hydrogen. The authors find that hydrogen fluoride traces molecular hydrogen pretty well and may prove useful here, SEE:http://arxiv.org/PS_cache/arxiv/pdf/1007/1007.2148v1.pdf

baric
2010-Jul-14, 09:27 PM
Using HF as a way to track atomic H is an interesting concept. I'm not sure I understand, though, why we can't measure the H directly. Is the absorption spectra for H weak so that it cannot be measured? Will the mapping of HF distribution give us additional insight into the mass of molecular clouds?

I guess I'm not sure of the benefits of using this technique. Enlighten me, if you can!

trinitree88
2010-Jul-15, 08:00 PM
Using HF as a way to track atomic H is an interesting concept. I'm not sure I understand, though, why we can't measure the H directly. Is the absorption spectra for H weak so that it cannot be measured? Will the mapping of HF distribution give us additional insight into the mass of molecular clouds?

I guess I'm not sure of the benefits of using this technique. Enlighten me, if you can!

baric. Three types of hydrogen.
1. atomic hydrogen so hot that it has ionized, and as the electron cascades it's way back to the proton over quantized energy levels...it emits the characteristic "fingerprint" of hydrogen, it's spectrum from infrared through ultraviolet...Lyman, Balmer, Paschen, Brackett, Pfund. Like the Orion nebula.
2. neutral atoms of hydrogen can have electron and proton with paired spins or opposite spins. The transition involves the 21.1 cm radio line, and radioastronomers map neutral atom clouds this way.
3. cold molecular hydrogen.... H2....which is radio and optical quiet, so it is traced by the companion gas carbon monoxide with which it is often found. (This is a little more iffy, and may yet show up some of our missing baryons as more molecular hydrogen, but newer instruments will be required)

for a primer see:http://www.astronomynotes.com/ismnotes/s3.htm