AN EXPANDED VERY LARGE ARRAY AND CARMA STUDY OF DUSTY DISKS AND TORII WITH LARGE GRAINS IN DYING STARS

作者：Sahai R^*; Claussen M J; Schnee S; Morris M R; Sanchez Contreras C

来源：Astrophysical Journal Letters, 2011, 739(1): L3.

DOI：10.1088/2041-8205/739/1/L3

• accretion, accretion disks
• binaries: general
• circumstellar matter
• radio continuum: stars
• stars: AGB and post-AGB
• stars: mass-loss

We report the results of a pilot multiwavelength survey in the radio continuum (X, Ka, and Q bands, i.e., from 3.6 cm to 7 mm) carried out with the Expanded Very Large Array (EVLA) in order to confirm the presence of very large dust grains in dusty disks and torii around the central stars in a small sample of post-asymptotic giant branch (pAGB) objects, as inferred from millimeter (mm) and submillimeter (submm) observations. Supporting mm-wave observations were also obtained with the Combined Array for Research in Millimeter-wave Astronomy toward three of our sources. Our EVLA survey has resulted in a robust detection of our most prominent submm emission source, the pre-planetary nebula (PPN) IRAS 22036+5306, in all three bands, and the disk-prominent pAGB object, RV Tau, in one band. The observed fluxes are consistent with optically thin free-free emission, and since they are insignificant compared to their submm/mm fluxes, we conclude that the latter must come from substantial masses of cool, large (mm-sized) grains. We find that the power-law emissivity in the cm-to-submm range for the large grains in IRAS22036 is nu(beta), with beta = 1-1.3. Furthermore, the value of beta in the 3-0.85 mm range for the three disk-prominent pAGB sources (beta <= 0.4) is significantly lower than that of IRAS22036, suggesting that the grains in pAGB objects with circumbinary disks are likely larger than those in the dusty waists of pre-planetary nebulae.

• 出版日期2011-9-20