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

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SCIENTIFIC ABSTRACT

 Most binary T Tauri stars have separations of
 the same order as the size assumed for the circumstellar disks
 of these stars (one hundred or several hundred AU). This proposal is to
 investigate a representative sample of T Tauri binaries with separations
 ranging from less than one AU to about 1000 AU by means of
 multiband photometry from 3-200 micron. It is expected that interaction
 of the binary components with their circumstellar disks or their
 common circumbinary disk will reflect in the broad band energy
 distribution. By comparison with a sample of single
 stars (given by the ISOPHOT proposal "Evolution of disks around T Tauri
 stars") we hope to see clear evidence for this interaction
 between the binary components and their disks
 and thus to provide necessary observational constraints for
 the dynamical evolution of these systems.

The object list is taken from recent studies on the multiplicity
of T Tauri stars by Simon et al.(1992), Ghez et al.(1993),
Reipurth and Zinnecker(1993) and Leinert et al.(1993). Our main selection
criteria were to avoid confusion by neighboring T Tauri stars and to avoid
regions of strong cirrus emission.


=== summary ===

OBSERVATION SUMMARY

We propose to study three groups of binaries
     group 1. Spectroscopic and close lunar occultation binaries
              with separations of at most a few AU.
     group 2. Binaries with separations around 10-50 AU.
     group 3. Binaries with separations exceeding the typical disk sizes
              of about 100 AU.
With progressively larger separations the interactions with the disks
are expected to show at progressively longer wavelenghts.

PERFORMANCE TIME OVERVIEW

    Observations          priority 1   priority 2   priority 3   sum
    ------------------------------------------------------------------
    broadband photometry    ---        15096 s      1776 s     16872 s
    ------------------------------------------------------------------
                                        (4.2 h)     (0.5 h)    (4.7 h)

=== Detailed observing plan ===

The observations will be performed at 8 wavelengths between 3.6 micron
and 90 micron in triangular chopping mode, and about half of the sources
will be observed at 160 micron as well, using a five point raster.
The size of the diaphragms is 52 arcsec 
for filters P_3.6 to P_25. There are no restrictions to the 
actual position angle of the chopping direction.
The broad band photometry can be realized by two or three AOTs which are
concatenated.
  Our emphasis is on the accurate determination of the
energy distribution at long wavelengths for sources with good IRAS
detection, and on detecting the long wavelength emission
for those sources with low or missing IRAS detection.
   With the given integration times the flux limit for a typical source
brightness one of 0.3 Jy is 10-30 mJy in the absence of cirrus (S/N about 10).
Cirrus confusion is about 100 mJy at a  wavelength 100 micron for a cirrus
brightness of 15 MJy/sr. With a typical far infrared source brightness of
around 1 Jy, again a S/N of about 10 results.


    Filter     t(on object)  t(performance) diaphragm(") chopthrow(")
    ------------------------------------------------------------------
    P_3.6          32 s          539 s         52           90
    P_4.85         32 s                        52           90
    P_7.3          32 s                        52           90
    P_11.5         32 s                        52           90
    P_16           32 s                        52           90
    P_25           32 s                        52           90

    C_60           32 s          305 s                     150
    C_90           32 s                                    150

    C_160          32 s          302 s         --- raster scan ---

    Acquisition                  180 s
    -------------------------------------------------------------------