interstellar neutral clouds, located close to newly born hii regions, are exposed to the ionizing radiation of the central star, and the expanding ionized gas drives a strong shock front into them. an ionized boundary layer is formed which transforms ultraviolet photons to the optical regime, making this layer to be observable as a bright rim at the surface of the clouds. little is known on the properties of dust grains processed by the shock front, although this information is required by calculations of thermal balance of ionized regions as well as by attempts which use infrared emission as diagnostic tool for the derivation of physical parameters of the emitting region. we propose a comparative study of dust properties in 3 bright rims located at different distances from the central star of the hii region ic1396. they are excited by the same star but exposed to different velocity shocks, so their study may reveal the dependence of infrared spectral distribution on shock velocity, and may answer whether infrared data could be used for the derivation of shock velocity. the results also may help to interpret the variations in dust size distribution found by iras in interstellar clouds. we derive properties such as temperature and size distribution of dust particles in interstellar bright rims on the basis of their spectral distribution. this goal requires the observation of the infrared spectrum of the rims in the whole infrared regime and, in addition, observation of the spectral lines emitted by macromolecules (pahs). the existing iras data base consists of data taken at 12, 25, 60, and 100 micron, and contains little information on both the very small and very cold dust component. iso is perfectly suited for this kind of observations because of its observing capacity in the 3 to 240 micron wavelength range, and the filter set fitted for macromolecule features.
Instrument
CAM04 , PHT03
Temporal Coverage
1996-02-08T07:47:01Z/1997-01-11T14:34:08Z
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.
European Space Agency, 1999, Study Of Dust Particles In Bright-Rimmed Clouds Comma Part 1, 1.0, European Space Agency, https://doi.org/10.5270/esa-s7yn518
