Presentation #229.06 in the session “Circumstellar Disks 2”.
Among the YSOs and disks that are actively accreting material onto the central protostar, exists a class of objects that exhibit extreme outbursts, likely due to periods of enhanced accretion. These objects, called FUors and EXors, may represent a relatively common stage of stellar and disk evolution. The significantly enhanced luminosity from the outburst can impact the circumstellar environment that may eventually go on to form planets.
We present ALMA and VLA observations of EX Lupi, the prototypical EXor outburst system. We use these data, along with archival ALMA data, to fit radiative transfer models to EX Lupi’s circumstellar disk in its quiescent state following an extreme outburst in 2008. The best fit models show a compact disk with a characteristic dust radius of 45 au and a total mass of 0.01 solar masses. Our modeling suggests grain growth to sizes of at least 3 mm in the disk, possibly spurred by the recent outburst, and an ice line that has migrated inward to 0.2-0.3 au post-outburst. At low frequencies, we detected significant emission over the expected thermal disk emission which we attribute primarily to stellar (gyro)synchrotron and free-free disk emission. The presence of this low frequency emission is consistent with a > 3 kG stellar magnetic field. Altogether, these results highlight what may be a common impact of outbursts on the circumstellar dust.