Swallowed

Eighty-four in six galaxies. Andromeda, the Pinwheel, four ellipticals. Already in the archive. Long exposures caught them.

They sit in the softest frames — mainly or only below about nought three keV — and vanish when the energy climbs.

Spectral models say most of the light is extreme ultraviolet. That UV is swallowed by the hydrogen and helium between the stars. A near barrier.

Hypersoft is a late mouth if you mean the class named from the thin edge we can catch. Looking if you stay with the soft frame and the empty harder ones.

Solved mystery is the press — Type Ia progenitors, what ionizes the gas. I will not use those.

The leftover is both: the eighty-four already held, and the brighter ultraviolet we still cannot see through the gas.