A Comprehensive Study of Proto-Planetary Disks around Herbig Ae Stars using Long-Baseline Infrared Interferometry.

Interferometry;Monte Carlo;Radiative Transfer;Pre-main-Sequence;Circumstellar Material;Proto-planetary;Science;Astronomy and Astrophysics

Tannirkulam, Ajay-Kumar M.Calvet, Nuria P. ;

University of Michigan

关键词: Interferometry;    Monte Carlo;    Radiative Transfer;    Pre-main-Sequence;    Circumstellar Material;    Proto-planetary;    Science;    Astronomy and Astrophysics;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/61678/atannirk_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Planetary systems are born in circumstellar disks around young stellar objects (YSOs) and the disk is thought to play a major role in the evolution of planetary systems. A good understanding of disk structure and its time evolution is therefore essential in comprehending planet formation, planet migration and the diversity of planetary systems. In this thesis, I use high angular resolution observations and state-of-the-art radiative transfer modeling to probe circumstellar disk structure and validate current disk models.First, I discuss models and observations of the gas-dust transition regionin YSOs.The dust component in circumstellar disks gets truncated at a finite radius from the central star, inside of which it is too hot for dust to survive. The truncated disk forms an ``evaporation front;;;; whose shape depends sensitively on dust properties. The possibility of using the front as a probe of the dust physics operating in circumstellar disksis explored. The Center for High Angular Resolution Astronomy~(CHARA)near-infrared~(near-IR) array is used to resolve out the evaporation front in the Herbig Ae stars MWC275 and AB Aur, and the presence of an additional near-IR opacity source within the ``conventional;;;; dust destruction radius is reported. Second, I describe comprehensive disk models that simultaneously explain the spectral energy distribution (from UV to milli-meter )and long-baseline interferometry (from near-IR to mm)of Herbig Ae stars. The models are constrained with a wide range of data drawnfrom the literature as well as new interferometric observations in the K-bandwith the CHARA array and in themid-IR with the novel Keck Segment Tilting Experiment.I showthat themid-IR size of MWC275 relativeto AB~Aur is small, suggesting that dust grains in the outer disk of MWC275 are significantly more evolved/settled than the grains in the AB~Aur disk. I concludewitha discussion on exciting prospects for measuring the gas-disk morphology on scales of fractions of an AU with the CHARA array, introducing a new powerful toolto understand the ``star-disk connection;;;;.