No telescope at wavelengths of 12.5 nm to 125 nm?
- From: "David.Paterson@xxxxxxxx" <David.Paterson@xxxxxxxx>
- Date: Thu, 14 Jun 2007 22:53:07 -0700
Am I right in thinking that there is no telescope on Earth or in space
that is observing over any part of the wavelength range of 12.5 nm to
125 nm (10 eV to 100 eV) ?
If so, that's a very great shame.
For example, aluminium is a great reflector of UV at energies up to
15.2 eV (80 nm) even at zero angle of incidence (85% reflectivity at
14 eV). Beyond that I strongly suspect that graphite is a strong UV
reflector past 30 eV (40 nm). Changing to a non-zero angle of
incidence would make the reflection even better, 45 degrees is
sometimes used for UV.
The resolution of any telescope is limited by mirror diameter /
wavelength which suggests that a fairly small telescope (easy to lift
into space) could produce image resolutions far better than those of
the Hubble-ACS and James Webb telescopes. Provided, of course, that
the mirror can be ground accurately enough. A sphere of silica about
to be ground not far from here will have an accuracy (peak to trough)
of 35 nm or better, so accurate grinding of a small mirror should be
possible.
You may wonder what could be observed at those wavelengths? Supernova
remnants, white dwarf supernova candidates, and hot new stars for
starters. I find what are called "super-soft-sources" particularly
interesting. They are white dwarf stars that are accreting matter so
fast that they have continuous hydrogen burning on their surfaces.
They shine most brightly in this wavelength band. An accreting white
dwarf star is the progenitor of a type 1 supernova.
.
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