THE INFRARED COLORS OF MAIN-SEQUENCE STARS - HOW MUCH CIRCUMSTELLAR DEBRIS IS NORMAL

We have been awarded NASA Key Project observing time on ISO, in order to establish the true frequency of far-infrared excesses in a volume-l imited sample of main sequence and related stars, and address the rela tive success or failure of single stars in processes related to the fo rming of planetary systems. For a volume-limited subset of main sequen ce and related stars, PBT03 measurements at 3.6, 11.5, 20 and 60 micro n will be obtained, using a 120 arsec aperture in all cases to elimina te possible companion confusion with differing apertures, to ascertain spectral energy distributions. For the M dwarfs, 100 micron observati ons will also be obtained. For some, brighter sources, more extensive wavelength coverage and improved spatial resolution will be attempted, using CAM and SWS. Spatially over-sampled PHOT observations will be m ade at 60 micron of the brightest and nearest Vega-Like sources to mea sure the characteristic sizes of the emitting regions and obtain some information regarding their shapes and orientations. The goal is not a map, but scan profiles along 3 position angles which can be deconvolv ed to find the intrinsic size and shape of the half-maximum contour of the emitting region. Photometry of selected lines of sight through th e zodiacal dust will also be carried out to look for outer solar syste m (Kuiper Belt) material. Observation at a range of wavelengths, eclip tic latitudes and at 2 epochs is designed to help untangle foreground Zodiacal from background Kuiper flux, not necessarily to look for indi vidual macroscopic objects.