EXPORT_UXOR_PROGRAM

EXPORT UXOR-Program

Coordinated, multi-wavelength observations of young stars with protoplanetary disks have been invaluable in establishing

the system inclination to our line of sight: polarization observations are most sensitive to those systems viewed close to edge-on to our sight line.
the presence of dust in the immediate vicinity of the star, visible both in the polarization signature and in the photometric behaviour.
in the intermediate-mass systems that beta Pic-like infall activity is seen within some degrees of the disk mid-plane.
that the intermediate-mass systems with the blueing effect are characterized by grain populations which are significantly larger than interstellar grains.
More sporadic observations have suggested (Hutchinson et al. 1994; Sitko et al. 1994) that the optical minima may be accompanied by increases in the thermal IR continuum for these objects. If supported, such observations could indicate the injection of grains into the immediate vicinity of the star, and could suggest that source of the small grains (parent bodies) must be on high eccentricity orbits.

Obtaining coordinated, multi-wavelength, multi-telescope observations has traditionally been "challenging". The EXPORT Team hopes to:

obtain more comprehensive observations including optical and near-IR photometry, optical polarimetry, intermediate and high resolution optical spectroscopy of selected stars during several observing runs (~4 days each) using the resources of the Canary Islands Observatories (Scheduled EXPORT observing runs)
There are only a limited number of coordinated polarimetric and photometric studies of these systems, typically made without near-IR photometry, and optical spectroscopy. Through the 1998 La Palma International Time Program, we hope to mitigate this deficiency with observations of a number of northern systems with observations made in 4 synoptic runs.
One goal of the study will be to extend observations to a number of weak T Tauri stars, (e.g. young Suns) and selected classical T Tauri stars (younger Suns) which are suspected of also being viewed through their disks. We hope to determine whether there are significant differences in the evolution of the small grain population in these disks and/or the nature of the infall activity as a function of stellar mass.
Some of our runs may have additional observations coordinated with them including BASS IRTF observations during the May 1998 run, CTIO optical spectroscopy (delta t=4 hours from La Palma) over May 17-22, and HST STIS observations of one object during July 28-31.