Parameterizing the dust around Herbig Ae/Be stars: Multiwavelength imaging, radiative transfer modeling, and near-infrared instrumentation
by Doering, Ryan Lee, Ph.D., UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN, 2008, 150 pages; 3337749

Abstract:

Herbig Ae/Be stars are considered the intermediate-mass analogs of the low-mass pre-main sequence T Tauri stars. Observations reveal that they are surrounded by dusty matter that may provide the solid-state material for building planets. Determining the dust parameters provides constraints for planet formation theory, and yields information about the matter around intermediate-mass stars as they approach the main sequence. In this dissertation, I present the results of a multiwavelength imaging and radiative transfer modeling study of Herbig Ae/Be stars, and a near-infrared instrumentation project, with the aim of parameterizing the dust in these systems.

The Hubble Space Telescope was used to search for optical light scattered by dust in a sample of young stars. This survey provided the first scattered-light image of the circumstellar environment around the Herbig Ae/Be star HD 97048. Structure is observed in the dust distribution similar to that seen in other Herbig Ae/Be systems. A ground-based near-infrared imaging study of Herbig Ae/Be candidates was also carried out. Photometry was collected for spectral energy distribution construction, and binary candidates were resolved. A mid-infrared image of the low-mass debris system, AU Microscopii, is presented, being relevant to the study of Herbig Ae/Be stars.

Detailed dust modeling of HD 97048 and HD 100546 was carried out with a two-component geometry consisting of a flared disk and an extended envelope. The models achieve a reasonable global fit to the spectral energy distributions, and produce images with the desired geometry. The disk midplane densities are found to go as r-0.5 and r -1.8, giving disk dust masses of 3.0 × 10-4 and 5.9 × 10-5 [special characters omitted] for HD 97048 and HD 100546, respectively. A gas-to-dust mass ratio lower limit of 3.2 was calculated for HD 97048.

In order to advance the imaging capabilities available for observations of Herbig Ae/Be stars, I have participated in the development of the WIYN High Resolution Infrared Camera. The instrument operates in the near-infrared (∼0.8 – 2.5 μm), includes 13 filters, and has a pixel size of ∼0.1&inches;, resulting in a field of view of ∼3' × 3'. An angular resolution of ∼0.25&inches; is anticipated. I provide an overview of the instrument, and report performance results with an emphasis on detector characterization.

 
AdviserMargaret Meixner
SchoolUNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
SourceDAI/B 69-11, p. , Jan 2009
Source TypeDissertation
SubjectsAstronomy
Publication Number3337749
Adobe PDF Access the complete dissertation:
 

» Find an electronic copy at your library.
  Use the link below to access a full citation record of this graduate work:
  http://gateway.proquest.com/openurl%3furl_ver=Z39.88-2004%26res_dat=xri:pqdiss%26rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation%26rft_dat=xri:pqdiss:3337749
  If your library subscribes to the ProQuest Dissertations & Theses (PQDT) database, you may be entitled to a free electronic version of this graduate work. If not, you will have the option to purchase one, and access a 24 page preview for free (if available).

About ProQuest Dissertations & Theses
With over 2.3 million records, the ProQuest Dissertations & Theses (PQDT) database is the most comprehensive collection of dissertations and theses in the world. It is the database of record for graduate research.

The database includes citations of graduate works ranging from the first U.S. dissertation, accepted in 1861, to those accepted as recently as last semester. Of the 2.3 million graduate works included in the database, ProQuest offers more than 1.9 million in full text formats. Of those, over 860,000 are available in PDF format. More than 60,000 dissertations and theses are added to the database each year.

If you have questions, please feel free to visit the ProQuest Web site - http://www.proquest.com - or call ProQuest Hotline Customer Support at 1-800-521-3042.