Browsing by Author "Harris, R.J."

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    The Millimeter Continuum Size–Frequency Relationship in the UZ Tau E Disk
    (IOP, 2018) Tripathi, Anjali; Andrews, Sean M.; Birnstiel, Tilman; Chandler, Claire J.; Isella, Andrea; Pérez, Laura M.; Harris, R.J.; Ricci, Luca; Wilner, David J.; Carpenter, John M.; Calvet, N.; Corder, S.A.; Deller, A.T.; Dullemond, C.P.; Greaves, J.S.; Henning, Th.; Kwon, W.; Lazio, J.; Linz, H.; Testi, L.
    We present high spatial resolution observations of the continuum emission from the young multiple star system UZ Tau at frequencies from 6 to 340 GHz. To quantify the spatial variation of dust emission in the UZ Tau E circumbinary disk, the observed interferometric visibilities are modeled with a simple parametric prescription for the radial surface brightnesses at each frequency. We find evidence that the spectrum steepens with radius in the disk, manifested as a positive correlation between the observing frequency and the radius that encircles a fixed fraction of the emission (R eff ∝ ν 0.34±0.08). The origins of this size–frequency relation are explored in the context of a theoretical framework for the growth and migration of disk solids. While that framework can reproduce a similar size–frequency relation, it predicts a steeper spectrum than that observed. Moreover, it comes closest to matching the data only on timescales much shorter (≤1 Myr) than the putative UZ Tau age (~2–3 Myr). These discrepancies are direct consequences of the rapid radial drift rates predicted by models of dust evolution in a smooth gas disk. One way to mitigate that efficiency problem is to invoke small-scale gas pressure modulations that locally concentrate drifting solids. If such particle traps reach high-continuum optical depths at 30–340 GHz with a ~30%–60% filling fraction in the inner disk (r lesssim 20 au), they can also explain the observed spatial gradient in the UZ Tau E disk spectrum.