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The planet formation process shapes the morphology and grain size distribution of circumstellar disks, encoding the formation history of a given system. Remnants of planet formation, such as comets and asteroids, collisionally evolve and can replenish the dust and small solids that would otherwise be cleared on short timescales. These grains are observed through their thermal emission at submm to cm wavelengths and the spectrum of their emission reveals details of the grain population. However, one confounding parameter in studying these grains around stars is the stars themselves. The emission from stars in the mm/cm is non-trivial and generally not well-constrained.
I will present examples of debris systems studied by ALMA and the VLA, in which unconstrained stellar emission may be contributing to the observed flux densities. Such contamination in turn biases the inferred emission from the disk and the corresponding dust properties. In some cases, the behavior of the observed A/B stars can exhibit an emission profile that has similarities to that of the Sun's mm/cm emission, although the same processes are not thought to necessarily occur in the atmospheres of massive stars. To address the uncertainty in stellar emission at mm/cm wavelengths, I present ongoing radio observations of Sirius A, which is a bright, nearby star with no known debris. Sirius A can be used as an observationally determined standard for stellar atmosphere modeling and debris disk studies around A-type stars, as well as to take the first step toward characterizing potential intrinsic uncertainty in stellar emission at these wavelengths. This presentation highlights the effort to characterize stellar atmospheres through a project known as MESAS (Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter wavelengths) which is imperative to the success of current and future debris disk studies.
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