in order to study the physical conditions in low-excitation photodissociation regions we propose a detailed spectroscopic study of two bright h2 emission knots in the prototypical reflection nebula ngc 2023. a first analysis of our sws observations of the s140 pdr (timmermann et al. 1996, attached) motivates us to also request followup observations of s140 to clarify questions raised regarding the gas temperature, the ortho-para ratio, and the iron abundance. to comparatively study pdrs from significantly harder radiation fields and the effects of rapidly propagating ionization fronts on the pdr structure we propose to observe several molecular clumps illuminated by early type o stars. for this we selected targets in the w5 and rosette hii regions.
Instrument
LWS01 , SWS02
Temporal Coverage
1997-08-09T11:10:33Z/1997-08-17T12:17:48Z
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.
