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Dissertation/Thesis Abstract

HD 100453: An evolutionary link between protoplanetary disks and debris disks
by Collins, Karen Alicia, M.S., University of Louisville, 2008, 127; 1458913
Abstract (Summary)

Herbig Ae stars are young stars usually surrounded by gas and dust in the form of a disk and are thought to evolve into planetary systems similar to our own. We present a multi-wavelength examination of the disk and environment of the Herbig Ae star HD 100453A, focusing on the determination of accretion rate, system age, and disk evolution. We show that the accretion rate is characterized by Chandra X-ray imagery that is inconsistent with strongly accreting early F stars, that the disk lacks the conspicuous Fe II emission and continuum seen in FUV spectra of actively accreting Herbig Ae stars, and that FUSE, HST, and FEROS data suggest an accretion rate below ∼2.5×10 -10 [special characters omitted] yr-1. We confirm that HD 100453B is a common proper motion companion to HD 100453A, with spectral type M4.0V – M4.5V, and derive an age of 14 ± 4 Myr. We examine the Meeus et al. (2001) hypothesis that Meeus Group I sources, which have a mid-IR bump which can be fitted by a black body component, evolve to Meeus Group II sources, which have no such mid-IR bump. By considering stellar age and accretion rate evidence, we find the hypothesis to be invalid. Furthermore, we find that the disk characteristics of HD 100453A do not fit the traditional definition of a protoplanetary disk, a transitional disk, or a debris disk, and they may suggest a new class of disks linking gas-rich protoplanetary disks and gas-poor debris disks.

Indexing (document details)
School: University of Louisville
School Location: United States -- Kentucky
Source: MAI 47/02M, Masters Abstracts International
Subjects: Astronomy
Publication Number: 1458913
ISBN: 978-0-549-83520-2
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