Circumstellar dust disks in Taurus-Auriga: the submillimeter perspective.
ANDREWS S.M. and WILLIAMS J.P.
Abstract (from CDS):
We present a sensitive, multiwavelength submillimeter continuum survey of 153 young stellar objects in the Taurus-Auriga star formation region. The submillimeter detection rate is 61% to a completeness limit of ∼10 mJy (3 σ) at 850 µm. The inferred circumstellar disk masses are lognormally distributed with a mean mass of ∼5x10–3M☉and a large dispersion (0.5 dex). Roughly one-third of the submillimeter sources have disk masses larger than the minimal nebula from which the solar system formed. The median disk-to-star mass ratio is 0.5%. The empirical behavior of the submillimeter continuum is best described as Fν∝ν2.0±0.5 between 350 µm and 1.3 mm, which we argue is due to the combined effects of the fraction of optically thick emission and a flatter frequency behavior of the opacity compared to the interstellar medium. The latter effect could be due to a substantial population of large dust grains, which presumably would have grown through collisional agglomeration. In this sample, the only stellar property that is correlated with the outer disk is the presence of a companion. We find evidence for significant decreases in submillimeter flux densities, disk masses, and submillimeter continuum slopes along the canonical infrared spectral energy distribution evolution sequence for young stellar objects. The fraction of objects detected in the submillimeter is essentially identical to the fraction with excess near-infrared emission, suggesting that dust in the inner and outer disks is removed nearly simultaneously.