{"product_id":"9781581122800","title":"High Angular Resolution Studies Of The Structure And Evolution Of Protoplanetary Disks","description":"Young stars are surrounded by massive, rotating disks of dust and gas, which supply a reservoir of material that may be incorporated into planets or accreted onto the central star. In this dissertation, I use high angular resolution observations at a range of wavelengths to understand the structure, ubiquity, and evolutionary timescales of protoplanetary disks.\u003cp\u003eFirst, I describe a study of Class I protostars, objects believed to be at an evolutionary stage between collapsing spherical clouds and fully-assembled young stars surrounded by protoplanetary disks. I use a Monte Carlo radiative transfer code to model new 0.9 micron scattered light images, 1.3 mm continuum images, and broadband spectral energy distributions. This modeling shows that Class I sources are probably surrounded by massive protoplanetary disks embedded in massive infalling envelopes. For the best-fitting models of the circumstellar dust distributions, I determine several important properties, including envelope and disk masses, mass infall rates, and system inclinations, and I use these results to constrain the evolutionary stage of these objects.\u003c\/p\u003e\u003cp\u003eSecond, I discuss observations of the innermost regions of more evolved disks around T Tauri and Herbig Ae\/Be stars, obtained with the Palomar Testbed and Keck Interferometers. I constrain the spatial and temperature structure of the circumstellar material at sub-AU radii, and demonstrate that lower-mass stars are surrounded by inclined disks with puffed-up inner edges 0.1-1 AU from the star. In contrast, the truncated inner disks around more massive stars may not puff-up, indicating that disk structure depends on stellar properties. I discuss the implications of these results for disk accretion, terrestrial planet formation and giant planet migration.\u003c\/p\u003e\u003cp\u003eFinally, I put these detailed studies of disk structure into a broader context by constraining the mass distribution and evolutionary timescales of circumstellar disks. Using the Owens Valley Millimeter Array, I mapped the millimeter continuum emission toward \u0026gt;300 low-mass stars in the NGC 2024 and Orion Nebula clusters. These observations demonstrate that the average disk mass in each cluster is comparable to the \"minimum-mass protosolar nebula,\" and that there may be disk evolution on one million year timescales.\u003c\/p\u003e","brand":"Universal-Publishers.com","offers":[{"title":"Default Title","offer_id":47050304684272,"sku":"9781581122800","price":25.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0737\/7593\/9824\/files\/9781581122800_p0.jpg?v=1763802720","url":"https:\/\/shop-qa.barnesandnoble.com\/products\/9781581122800","provider":"Barnes \u0026 Noble (DEV)","version":"1.0","type":"link"}