Contents of: VI/111/./abstract/EBECKLIN_DEBRIS02.abs

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SCIENTIFIC ABSTRACT
With ISO, we propose to study the physical nature and evolutionary history
of dust debris clouds around solar mass stars. These clouds, discovered by
IRAS, are thought to be related to planetary systems. The program will consist
of: (i) A photometric study of selected A, F, G, and K-type main sequence 
stars within 20 pc of the Sun. 100 stars have been selected with various
ages and multiplicity. (ii) A study of the evolutionary history of debris 
clouds from observations of  140 young open cluster stars and weak-line 
T Tauri stars. (iii) Search for excess emission from  20 known young main 
sequence field stars beyond 20 pc. (iv) Search for possible dust disks around 
degenerate stars. The investigation will clarify the relationship of the 
debris clouds, specific properties of stars, and place the phenomenon in the 
context of planetary formation.

OBSERVATION SUMMARY
We will investigate the excess emission from main sequence stars at 60 
micron and 100 micron using C100 and P3 in ISOPHOT. For the cluster stars 
we will use a sparse map and C100 (PHT37, PHT38, and PHT39). Each observation 
consists of a single stare on the object and then a corresponding stare on 
an adjacent sky, separated by 2 arcmin. For stability of the detectors, 
all observations in a sequence will be done at one wavelength and then a 
repeated reverse sequence at a second wavelength; The two sequences are 
concatenated together. Integration times on each of the source and sky will be 
160 sec at 60 micron and 96 sec at 100 micron. The required signal to noise 
for these cluster stars is unknown, since the photosphere will not be seen 
and the amount of excess depends on the unknown dust density.

For measurements of field stars and isolated cluster stars, either the 
photometer P3 or array C100 will be used, depending on the cirrus noise. 
If cirrus > 15 MJy/sr at 100 micron, C100 is used. In both cases a triangular 
wave chopping will be used. The peak to peak motion of the chopper throw will 
be 270 arcsec with the object in the center (the object will thus be 135 
arcsec from each extreme position). Integration times on source will typically 
be 128 sec at 60 micron and 64 sec at 100 micron. The 99 arcsec aperture 
will be used for the P3 observations with anticipated high S/N. The remaining
P3 observations will be made with the 79 arcsec aperture. We expect that the
photosphere will be detected for most stars stars with a S/N > 5.

Acquisition			180 sec
Initial instrument setup	 15 sec
Stability of detector		 90 sec
Filter change (2 Pos)		 20 sec
FCS exposures (for 2 filters)	 32 sec
Integration at 60 micron	384 sec
Integration at 100 micron	128 sec

Total time			849 sec

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