Highest resolution imaging of the dust destruction rim of planet-forming disks using the CHARA Array

Star and planet formation processes are among the least understood problems in astrophysics, generating numerous theories and questions over the decades. At this moment, there is no one comprehensive, predictive theory that can quantitatively explain how planetary systems form and eventually bring on life. Nevertheless, observational techniques are continually improving and progressing our understanding, providing new answers and questions about this elusive process. In particular, observations of young stars with dusty circumstellar disks hold key information that can help us answer questions about the formation of stellar systems, both similar to and different from our own. These disks are the birthplace of planets; they set the initial conditions for planet formation and host different physical processes across a large spatial range that change the morphology and composition of the disks as they evolve. The inner <1 astronomical unit (AU) regions are especially intriguing and will be the focus of this thesis. This is where star/disk interactions occur, including regulating the accretion of material onto the star, defining the dust sublimation front, hosting jets and winds that eject material outward, and placing limits on giant planet migration. The challenge to directly study these regions lies in the sub-milliarcsecond resolution required to resolve such small scales, which is unattainable by the world's largest singular optical telescopes or even the sub-millimeter interferometer ALMA. With the advent of long baseline optical interferometry, we finally have the resolving power required to probe the disks at the innermost regions. In this thesis, I use the world's largest optical interferometer, the CHARA Array, to study the inner regions of young stars on the more massive end, Herbig Ae/Be stars, as well as the lower mass T Tauri stars.


I present new images and models of Herbig Be stars and characterize the disks of T Tauri stars in H- and K-bands. I present the first images of two Herbig Be stars, V1295 Aql and MWC340. With observations using the upgraded MIRC-X instrument at the CHARA Array, and semi-simultaneous data from VLTI's H-band combiner PIONIER, I find a face-on disk around V1295 Aql showing asymmetries, mysterious inner emission, and first-ever imaged evidence of temporal variation at the inner rim. Imaging MWC340 led to an exciting discovery, unexpectedly revealing two disks instead of one. I use H- and K-band observations taken over 5 years at the CHARA array to resolve the binary systems, place constraints on the orbital parameters, and derive new stellar parameters for each central star. Furthermore, I explore the lower mass regime of young stars with a multi-wavelength survey of T Tauri stars at the highest resolution. I led a 4-year observing campaign at the CHARA Array with the newly-commissioned K-band instrument MYSTIC, which was specifically designed to image the redder, fainter stars. I present the initial results of a sample of the survey using geometric models to characterize their sizes and geometry. I consistently find the disk sizes to be larger in the K-band versus the H-band, meaning that the dusty disk gets more resolved at longer wavelengths. I discuss any interesting findings for individual objects and comment on results from previous studies when applicable.