{"product_id":"high-angular-resolution-studies-of-joshua-a-eisner-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. First, 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. Second, 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. Finally, 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.\u003cbr\u003e\u003cbr\u003e\u003cb\u003eAuthor:\u003c\/b\u003e Joshua A. Eisner\u003cbr\u003e\u003cb\u003eISBN-10:\u003c\/b\u003e 1581122802\u003cbr\u003e\u003cb\u003eISBN-13:\u003c\/b\u003e 9781581122800\u003cbr\u003e\u003cb\u003ePublisher:\u003c\/b\u003e Dissertation.com\u003cbr\u003e\u003cb\u003eLanguage:\u003c\/b\u003e English\u003cbr\u003e\u003cb\u003ePublished:\u003c\/b\u003e 06\/25\/2005\u003cbr\u003e\u003cb\u003ePages:\u003c\/b\u003e 240\u003cbr\u003e\u003cb\u003eFormat:\u003c\/b\u003e Paperback\u003cbr\u003e\u003cb\u003eWeight:\u003c\/b\u003e 0.96lbs\u003cbr\u003e\u003cb\u003eSize:\u003c\/b\u003e 9.69h x 7.44w x 0.51d","brand":"Joshua A. Eisner","offers":[{"title":"Paperback","offer_id":47305333407999,"sku":"9781581122800","price":25.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0662\/2982\/9887\/files\/img_79e3bb76-566a-4beb-81c1-d834eda96fd6.jpg?v=1758830599","url":"https:\/\/www.whiterainbookhouse.com\/products\/high-angular-resolution-studies-of-joshua-a-eisner-9781581122800","provider":"WR Book House","version":"1.0","type":"link"}