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Past ResearchProtoplanetary Disks

Here, we investigate the brightness drop at visible wavelengths and the brightening at near-IR wavelengths of HD 163296 using the MCRT code, HOCHUNK3D. We create three models to understand the events. Model 1 describes the quiescent state of the system. Model 2 describes the change in structure that led to the drop in brightness in 2001. Model 3 describes the structure needed to produce the observed 2002 brightening of the near-IR wavelengths. Models 2 and 3 utilize a combination of a disk wind and central bipolar flow. By introducing a filled bipolar cavity in Models 2 and 3, we were able to successfully simulate a jet-like structure for the star with a disk wind and created the drop and subsequent increase in brightness of the system. On the other hand, when the bipolar cavity is not filled, Model 1 replicates the quiescent state of the system.

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We present Atacama Large Millimeter/submillimeter Array (ALMA) 0.87 mm continuum, HCO  J = 4-3 emission line, and CO J = 3-2 emission line data of the protoplanetary disk around the pre-main sequence star PDS 70.  This system is of particular interest due to the existence of features that appear in the gas disk but are not present in the dust disk. Using the continuum data and Monte Carlo Radiative Transfer (MCRT) modeling, we find that the disk seems to have no strong segregation between dust grain sizes in the outer disk, but the inner disk does appear to be devoid of large grains. This is contrary to what is suggested in previous work, but is supported by the large silicate peaks in the spectral energy distribution (SED).

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Here, we used 5 epochs of near-IR observations of the protoplanetary disk around Herbig Ae star, MWC 480 which we obtained with SpeX spectrograph on NASA's InfraRed Telescope Facility (IRTF) between 2007 and 2013. The spectral energy distribution (SED) shows a variability of ~30% between 1.5-10 microns during this period which we investigated using the MCRT code HOCHUNK3D. Because MWC 480 exhibits bipolar flows, we utilized a structure that simulates an inner disk wind to model the near-IR variability whilst producing flux levels in the far-IR that are consistent with existing data.

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In this paper, we carried out Gemini Planet Imager (GPI) polarized intensity imagery of HD 100453 in Y, J and K1 bands that reveals an inner gap (9-18 au), an outer disk (18-39 au) with two prominent spiral arms, and two azimuthally localized dark features that are also present in the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) total intensity images. We use Monte Carlo Radiative Transfer (MCRT) code HOCHUNK3D to construct a model of the disk and show that the shadow morphology and location constrain both the thickness and orientation of the inner disk as well as the flaring of the outer disk. This offers an independent means of measuring structure in transitional disks.

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