Inner regions of protoplanetary disks host many complex physical processes such as star-disk interactions, magnetic fields, planet formation, and the migration of new planets. To directly study this
region requires milli-arcsecond angular resolution, beyond the diffraction limit of the world’s largest
optical telescopes and even too ...
Inner regions of protoplanetary disks host many complex physical processes such as star-disk interactions, magnetic fields, planet formation, and the migration of new planets. To directly study this
region requires milli-arcsecond angular resolution, beyond the diffraction limit of the world’s largest
optical telescopes and even too small for the mm-wave interferometer ALMA. However, we can use
infrared interferometers to image the inner astronomical unit. Here, we present new results from
the CHARA and VLTI arrays for the young and luminous Herbig Be star HD 190073. We detect
a sub-AU cavity surrounded by a ring-like structure that we interpret as the dust destruction front.
We model the shape with 6 radial profiles, 3 symmetric and 3 asymmetric, and present a model-free
image reconstruction. All the models are consistent with a near face-on disk with inclination . 20◦
,
and we measure an average ring radius of 1.35±0.2 mas (1.14 AU). Around 47.6% of the total flux
comes from the disk with 15% of that emission appearing to emerge from inside the inner rim. The
cause of emission is still unclear, perhaps due to different dust grain compositions or gas emission.
The skewed models and the imaging point to an off-center star, possibly due to binarity. Our image
shows a sub-AU structure, which seems to move between the two epochs inconsistently with Keplerian
motion and we discuss possible explanations for this apparent change.