Poster Presentation

Constraining dust grain growth in Class II protoplanetary disks by the (sub)millimeter broadband Taurus-Auriga survey

Author(s): Chia-Ying Chung (NTU/ASIAA), Hauyu Baobab Liu (ASIAA)

Presenter: Chia-Ying Chung (NTU/ASIAA)

Analyzing the (sub)millimeter spectral indices of protoplanetary disks have been a fundamental way to probe their dust grain sizes based on the direct relation between dust grain properties and opacity. Recent studies suggested that the observed anomalously low (~2) (sub)millimeter spectral indices of Class II disk is caused by the dominating dust scattering opacity when the maximum grain sizes are comparable to the Rayleigh limit of the wavelength. In this interpretation, the maximum grain sizes of the protoplanetary disks is around 0.1 mm. We present the SMA 200-400 GHz surveys towards a sample of 47 Class II disks in Taurus-Auriga region. From the densely-sampled (sub)millimeter spectra, we obtained the spectral indices as a function of frequency. The maximum grain sizes and dust disk mass in this survey may change our previous understanding of grain growth efficiency in protoplanetary disks. This eliminates the discrepancy in maximum grain sizes between (sub)millimeter spectral indices observations and polarization observations and solves the problem of insufficient mass budget for planet formation of protoplanetary disks. The ~0.1 mm maximum grain size may also indicate that the water-ice coated dust grains outside the 150-170 K snowline are not sticky enough to coagulate and overcome the bouncing barrier predicted by the theoretical studies.