CHIPS Questions and Answers
Why is it important to study diffuse emission in the CHIPS wavelength band?
The CHIPS band contains the significant majority of the radiated
power from diffuse hot interstellar plasma in its most probable
temperature range. Although X-ray and UV studies can detect plasma
at greater distances and map it with better angular resolution,
extrapolation of such measurements to a total plasma luminosity will be
fraught with significant uncertainty until spectroscopic observations
of diffuse emission are carried out in the CHIPS band.
Can observations with CHIPS disentangle all of the cooling mechanisms
that might be taking place in the local interstellar medium?
The various cooling mechanisms make observationally distinct predictions
for the emission in the CHIPS band. In combination with observations of
emission and absorption features at other wavelengths, CHIPS data will be
extremely helpful in disentangling these processes.
CHIPS will do an excellent job of constraining the electron temperature
through measurement of collisionally excited line emission.
Determination of the electron temperature is a crucial step in
understanding the cooling process.
Do current observational limits in the CHIPS band set interesting
constraints on the physical properties of plasma in the local bubble?
No. Current observational limits were set using instruments with
limited spectral resolution and many are well above the expected
emission-line fluxes. The marginal detection in 18 million seconds of
EUVE observations in regions where the soft X-rays are bright does
indicate that diffuse emission is present in our band.
What if the foreground absorption column is higher than you have estimated?
With nominal assumption, the bright iron emission lines will be
detected at 20 to 50 in each sky resel.
A higher absorption would reduce the line flux, but, barring some
wholly unexpected distribution of the local neutral material,
absorption will reduce the EUV emission to undetectable levels
in only a limited number of viewing directions.
The CHIANTI CIE plasma model predicts
somewhat brighter peak iron line fluxes than the Raymond & Smith
code used in our analysis.
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For more information about CHIPS please send an e-mail to Dr. Mark Hurwitz. If you have questions about or problems with this web page, please send an e-mail to the webmaster.
University of California, Space Sciences Laboratory
7 Gauss Way, Berkeley, CA 94720-7450, USA
CHIPS Project Manager: (510) 486-6340