Aster Taylor | Searcharxiv

arXiv2026

A Retrieval Framework for Observationally Constraining the Parameters of Circumplanetary Disks

As they form, giant planets are surrounded by disks of gas and dust sourced from the background circumstellar disk. Although there have been few detections to date, upcoming instruments are likely to discover many more of these systems in the coming decades. Accurate spectral modeling will enable these observations to constrain the properties of these forming systems. Towards this end, we have constructed a semianalytic model for the structure and radiative signatures of geometrically thick circumplanetary disks and their planet hosts. Fitting these radiative signatures to synthetic observations of a two-dimensional disk model then quantifies the parameter constraints that can be derived (subject to model assumptions). This machinery provides estimates of the values and uncertainties in system parameters, and some combinations of parameters have significantly smaller uncertainties than others. This model is then used to fit observations of real protoplanets, with good results. The derived parameters provide useful context about the local extinction, formation history, and initial entropy of these objects.

astro-ph.EP↗

arXiv2020

Far-Infrared Polarization Spectrum of the OMC-1 Star-Forming Region

We analyze the wavelength dependence of the far-infrared polarization fraction toward the OMC-1 star forming region using observations from HAWC+/SOFIA at 53, 89, 154, and 214 $μ$m. We find that the shape of the far-infrared polarization spectrum is variable across the cloud and that there is evidence of a correlation between the slope of the polarization spectrum and the average line-of-sight temperature. The slope of the polarization spectrum tends to be negative (falling toward longer wavelengths) in cooler regions and positive or flat in warmer regions. This is very similar to what was discovered in $ρ$ Oph A via SOFIA polarimetry at 89 and 154 $μ$m. Like the authors of this earlier work, we argue that the most natural explanation for our falling spectra is line-of-sight superposition of differing grain populations, with polarized emission from the warmer regions and less-polarized emission from the cooler ones. In contrast with the earlier work on $ρ$ Oph A, we do not find a clear correlation of polarization spectrum slope with column density. This suggests that falling spectra are attributable to variations in grain alignment efficiency in a heterogeneous cloud consistent with radiative torques theory. Alternative explanations in which variations in grain alignment efficiency are caused by varying gas density rather than by varying radiation intensity are disfavored.

astro-ph.GA↗