The Sizes and Depletions of the Dust and Gas Cavities in the Transitional Disk J160421.7-213028

Abstract

We report ALMA Cycle 2 observations of 230 GHz (1.3 mm) dust continuum emission, and 12 CO, 13 CO, and C 18 O J=2-1 line emission, from the Upper Scorpius transitional disk [PZ99] J160421.7-213028, with an angular resolution of ∼  0. 25 (35 au). Armed with these data and existing H-band scattered light observations, we measure the size and depth of the disk's central cavity, and the sharpness of its outer edge, in three components: sub-μm-sized "small" dust traced by scattered light, millimeter-sized "big" dust traced by the millimeter continuum, and gas traced by line emission. Both dust populations feature a cavity of radius ∼70 au that is depleted by factors of at least 1000 relative to the dust density just outside. The millimeter continuum data are well explained by a cavity with a sharp edge. Scattered light observations can be fitted with a cavity in small dust that has either a sharp edge at 60 au, or an edge that transitions smoothly over an annular width of 10 au near 60 au. In gas, the data are consistent with a cavity that is smaller, about 15 au in radius, and whose surface density at 15 au is  10 3 1 times smaller than the surface density at 70 au; the gas density grades smoothly between these two radii. The CO isotopologue observations rule out a sharp drop in gas surface density at 30 au or a double-drop model, as found by previous modeling. Future observations are needed to assess the nature of these gas and dust cavities (e.g., whether they are opened by multiple as-yet-unseen planets or photoevaporation).

A Survey of C2H, HCN, and C18O in Protoplanetary Disks

“…J1604-2130 shows a central gap for most molecular emission (see also van der Marel et al 2015), which is likely related to the presence of a large dust cavity (e.g. Zhang et al 2014;Dong et al 2017). The central emission dips for all molecules in IM Lup could be a dust opacity effect .…”

A Multi-instrument and Multi-wavelength High Angular Resolution Study of MWC 614: Quantum Heated Particles Inside the Disk Cavity*

“…However, some objects display a lack of emission in the near and mid-infrared (NIR and MIR) compared to full disk systems' spectral energy distributions (SEDs; e.g., Calvet et al 2005). These objects have a disk with a large dust-depleted inner cavity that has been spatially resolved with sub-mm interferometry for individual objects (e.g., Andrews et al 2011;van der Marel et al 2013van der Marel et al , 2016Canovas et al 2015;Pinilla et al 2015Pinilla et al , 2017Dong et al 2017;Sheehan & Eisner 2017) and are called transition disks because they are believed to undergo the process of disk clearing. Between the full disk and the transitional disk stage, pretransitional objects show a depletion in the MIR but still have an excess of NIR emission, likely caused by the presence of an inner disk interior to the cavity, forming a gapped disk (e.g., Espaillat et al 2014;Kraus et al 2017).…”

Measurement of Circumstellar Disk Sizes in the Upper Scorpius OB Association with ALMA

“…Since these systems are not representative of typical disks in Upper Sco, we excluded them from the present analysis and focused instead on understanding the broader population of ordinary disks. Zhang et al (2014) presented a detailed analysis of 2MASS J16042165-2130284 (see also Mayama et al 2012;Pinilla et al 2015;van der Marel et al 2015;Dong et al 2017).…”