Citation
Chou, Dean-Yi (1987) Development and Evolution of Magnetic Fields in Active Regions on the Sun. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/rkc8-g529. https://resolver.caltech.edu/CaltechETD:etd-09052008-154229
Abstract
The purpose of this thesis is to investigate the development and evolution of magnetic fields in new active regions on the sun. The major observations are digital magnetograms of the line-of-sight component of magnetic fields made with the high sensitivity videomagnetograph at the Big Bear Solar Observatory, and Hα filtergrams with the 1/4 Å Hα Zeiss filter.
This thesis consists of three themes. First, the separation velocity of emerging magnetic flux is investigated. I measure the separation velocities of opposite polarities of 24 new bipoles, and compare them with the theoretical values estimated by the present theory of magnetic buoyancy. The predicted velocities are higher than those observed. Second, the cooling time scale of growing sunspots is studied. I define the cooling time scale and derive it from the measurements of intensity and magnetic field strength of sunspots. The cooling time scales of the ten growing sunspots studied range from 0.5 to 9 hr. I also estimate the cooling time scale from two models, the Inhibition Model and the Alfven Wave Model, based on linear theory. Both models give cooling times of about 0.05 hr. Third, nonadiabatic effects in convective instabilities in thin flux tubes are examined. I study the convective instabilities in thin flux tubes by including a nonadiabatic term. I find that a flux tube is convectively stable for any field strength.
| Item Type: | Thesis (Dissertation (Ph.D.)) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Subject Keywords: | Astronomy | |||||||||
| Degree Grantor: | California Institute of Technology | |||||||||
| Division: | Physics, Mathematics and Astronomy | |||||||||
| Major Option: | Astronomy | |||||||||
| Thesis Availability: | Public (worldwide access) | |||||||||
| Research Advisor(s): |
| |||||||||
| Group: | Astronomy Department | |||||||||
| Thesis Committee: |
| |||||||||
| Defense Date: | 11 September 1986 | |||||||||
| Record Number: | CaltechETD:etd-09052008-154229 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechETD:etd-09052008-154229 | |||||||||
| DOI: | 10.7907/rkc8-g529 | |||||||||
| Related URLs: |
| |||||||||
| Default Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 3345 | |||||||||
| Collection: | CaltechTHESIS | |||||||||
| Deposited By: | Imported from ETD-db | |||||||||
| Deposited On: | 10 Sep 2008 | |||||||||
| Last Modified: | 16 Apr 2021 22:21 |
Thesis Files
![[img]](https://thesis.library.caltech.edu/style/images/fileicons/application_pdf.png)
|
PDF (Chou_d_1987.pdf)
- Final Version
See Usage Policy. 2MB |
Repository Staff Only: item control page
