we propose to map the far-ir dust emission from the small scale structures within the molecular cloud core l1498. recent spectral line maps (in high density tracers, ccs & cs) by nasa.s facilities at goldstone, the vla & ovro millimeter array show that cores previously thought to be single objects are actually composed of fragments with mass < 0.1 mo and sizes< 5000 au. as adjacent fragments show distinct chemical differences it appears that they are at different stages of evolution. coalescence of these fragments will lead to the build up of protostellar material. our objective is to study the properties of the gas and dust in a pre-protostellar environment and to identify an evolutionary sequence among the fragments leading up to the formation of protostars. l1498 core is ideal for understanding pre-star-formation evolution: dust emission in submm continuum observed at the 13co peak in l1498 suggests its spectral energy distribution has maximum below 400 micron at about 1 to 2 jy level; therefore, far-ir maps of iso are best suited to study the dust distribution. goldstone data show at least three fragments in ccs; the ovro interferometric map (in cs) of one fragment shows structures on smaller scale (< 30). these fragments are at varying evolutionary stages as indicated by the chemical differences (in ccs, hc3n, hc7n, cs, nh3). iso maps of l1498 at 100 and 200 micron will provide data on the dust emission and its variation from fragment to fragment as a function of pre-protostellar evolution determined by radio and iso map at 60micron. the iso and radio data will be used to derive the density structure unambiguously and to model the physical and chemical properties of the gas and dust in the pre-protostellar phase.
Instrument
PHT32 , PHT37 , PHT38 , PHT39
Temporal Coverage
1997-09-24T23:20:42Z/1997-09-25T02:27:28Z
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.
