this is a discretionary time proposal to attempt detection of the lowest pure rotational transition of hydrogen deuteride, hd, at 112.072 microns (um) toward the orion bar. before launch it was thought that this line would be routinely detected, but that has not proven to be the case. indeed, so far iso has failed to detect this important line in either emission or absorption outside of the solar system, for a number of possible reasons. this proposal therefore represents a last deep search, and indeed our last chance before sofia or first. observation of this line will allow a determination of the hd abundance, as well as probe the chemistry of molecular clouds. when compared with observations of molecular hydrogen, it will also allow a constraint to be placed on the d/h ratio, an important cosmological parameter.
Instrument
LWS01 , LWS04
Temporal Coverage
1998-02-15T23:58:17Z/1998-02-16T01:13:59Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
