NIRC2 Interferometric Imaging of the HD34282 Transition Disk's Small Grain Structure

The HD 34282 transition disk is a favorable location for protoplanet searches given its complex substructures that may be driven by planet formation. Early millimeter continuum studies revealed a cavity with a stellar-centric radius of 0".24 and a ring that extends to 1".15, which implied the presence of a 50 M_J companion with a separation of ∼0".1. We observed HD 34282 with Keck/NIRC2 in L' using nonredundant masking interferometry in order to simultaneously search for protoplanets at small separations (down to ∼0.5λ/D) and characterize the inner substructures of the transition disk. We fit geometric models to the data and find that a morphology with two disk components separated by a gap best describes the data. The inner component is comprised of scattering dust with a near-circular brightness distribution on the sky. The outer component can be modeled as a ring with a cavity that extends to ∼0.26 in radius, which is about 11° more inclined than measurements from past J-band observations of material near this region. We do not detect the 50 M_J companion but place an upper limit of ∼40 M_J on companions at ≳λ/D (0".08). We find that we are sensitive to a planet mass-times-accretion rate of ∼1 × 10^-6 M_J² yr^-1, or an accretion rate that could form a Jupiter analog in ≳1 Myr.