scientific abstract the aim of this proposal is to investigate the properties and life cycle of dust throughout the universe. we intend to fully study with isophot the dust in objects, too faint to be observed in the infrared by any other means than a cold telescope in space equipped with a sensitive photometer. this proposal will take advantage of the full spectral range 2.5-240 micrometres. we will utilize other studies of the central program (where often dust is not the scientific target) with the goal of building up a coherent data base for dust properties in different objects and locations. isophot has unique capabilities for the study of dust in the following two research areas and these have the highest priority: 1. the properties of dust in the cirrus clouds. 2. search for and properties of very cold dust (ca. 10 k). observation summary we emphasize that the various inter- and circumstellar sub-studies of this proposal will be analyzed and summarized with the goal to gain a comphrehensive picture of dust in the universe from the solar system to intergalactic space. the observational and technical approach is for most of our sub-studies similar, and is connected to the problems of measuring faint surface brightnesses and separating them from the often much brighter zodiacal emission. observing parameters (e.g.filters) and target lists for the mapping are given separately under the section scientific_justification. 1. cirrus and related clouds(autumn launch 72382 s/spring launch 72469s) faint cirrus and gas heating in cirrus/translucent clouds: abundances and properties of the various dust particles (pahs, small, large) will be studied in different areas of cirrus clouds. one of the targets, the ursa major cloud, has areas which consist mainly of hi, the other target, g300.2-16.8 (chamaeleon), is associated with molecular gas. l1780 (autumn launch) and l1642 (spring launch) contain a molecular gas core and associated hi gas with a distribution different from the molecular gas. only pht -p/c multifilter photometry is sensitive enough for these sources. galactic line-of-sight, reflection nebulae and bright molecular filaments; study of the pahs with pht-s in cirrus and cirruslike emission: (1) a long galactic line of sight at g28.6+0.8, and a reference position at g31.5-3.8 will be observed. (2) two reflection nebulae with different surface temperature of the central star (17000 k for ngc7023, 6800k for vdb133) will be studied in order to see differences in the pah features and continumm emission. (3) properties of dust particles (freshly) exposed to enhanced uv-radiation fields near hot stars and the gas heating will be studied in a bright cirrus- like molecular gas filament, the northern edge of the rho ophiuchii cloud (autumn launch) or part of the lamda orionis ring (l1582)(spring launch). 2. mapping of cold dust in dark clouds at 90 and 200 microns(78037 s/ 72717 s) the distribution and properties of dust in nearby molecular clouds. especially we are searching for condensations of very cold dust and for very early phases of newly-born (proto)stars. we will study the connection of dust distribution and dust properties to the presence of newly-formed stars. 3. multi-filter photometry of cold dust in dark clouds (26134 s/26134 s) locations with different degrees of star formation activity and optical extinction,and positions probably representative for very cold dust. l183 (autumn launch) and l1521b (spring) are clouds with high optical extinction and no star formation known. chamaeleon i is a molecular cloud which has areas with different degrees of star formation. 4. spectrophotometry of dust emission from circumstellar environments (6568 s/5952 s) we include planetary nebulae, iras sources showing a strong 21 micron dust feature, oxygen rich giants, one oh/ir star (crl 2199), and one carbon rich post agb star (crl 618). the objects cover different strengths of the unidentified infrared features at 21 micron and 30 micron. another important aspect is the search for the c60 molecule in the circustellar space (strong spectral lines at 7.1, 8.8 micron). we will test the hypothesis that the very broad structure in the interstellar extinction curve is caused by dust in circumstellar environment. 5. dust emission from the magellanic clouds(10934s/10934s) the metallicity, the dust-to-gas ratio and the uv radiation field in the magellanic clouds are known to be very different from the galaxy. for each of the magellanic clouds, 3 positions on cold and warm sources have been chosen to derive the spectral distribution of the surrounding extended component. in addition, the molecular cloud complex n159 will be mapped. 6. searches for cold dust in intergalactic and high velocity clouds (9772 s/9772s) linear raster strip scans are made at 120 and 180 microns across three objects, representative of environments where dust has so far not been detected by iras or any other means: leo intergalactic cloud, coma cluster of galaxi
Instrument
PHT03 , PHT25 , PHT40
Temporal Coverage
1997-03-11T05:47:40Z/1997-03-11T10:19:18Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds 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.
