Combining our results with those obtained by André & Montmerle (1994) for a sample of 21 X-ray selected T Tauri stars (3 additional detections) we improve the statistical significance of our conclusions. As the frequency of circumstellar disks and the disk properties might depend on the selection criteria as well as local conditions, comparison is made with 1.3 mm surveys of H selected T Tauri stars in Chamaeleon, Lupus, Ophiuchus, and Taurus-Auriga.
In order to study the mass of cold dust in multiple systems we also observed a sample of 15 well known binaries, triples, and quadruples by 1.3 mm photometry. From these observations we report the 1.3 mm detection of 4 multiple systems. It seems that the measured 1.3 mm flux density increases slightly with increasing binary separation.
In addition, we have mapped the hierarchical triple SR 24 at = 1.3 mm with the 7-channel bolometer array (Figure ). We detected cold dust emission only from the southern component with a peak intensity of 230 mJy and a corresponding circumstellar disk mass of 0.035 M (gas + dust), while for the northern component we derived an upper limit of 10 of the SR 24S peak flux density. The non-detection of 1.3 mm emission from SR 24N suggests a lack of cold circumstellar dust in the outer part of the disk, which might have been cleared by the close infrared companion away from SR 24N.
Astronomy & Astrophysics 330, 549 (1998)
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Figure: SR 24N/S mapped at = 1.3 mm with the MPIfR 7-channel bolometer array mounted at the IRAM 30 m MRT. Contour lines correspond to 10, 20, 30, , 90 percent of peak intensity ( 230 mJy) before (top) and after (center) deconvolution with a Gaussian maximum likelihood algorithm using maps of Uranus and Mars as point spread functions. Crosses mark the positions of the optical counterparts ( = 16.0, = 15.9, ang. sep. = 52, pos. ang. = 348 ). For comparison, the mid infrared (N-band) image of SR 24N/S obtained with TIMMI mounted at the ESO 3.6 m telescope on La Silla, Chile (pixel scaling 034/pix; Stanke & Zinnecker 1998) is given in the bottom panel. Both the northern and the southern component show roughly equal emission (F = 1.3 Jy and F = 1.6 Jy at 10 m).