Sign on

SAO/NASA ADS Astronomy Abstract Service


· Find Similar Abstracts (with default settings below)
· Full Refereed Journal Article (PDF/Postscript)
· Full Refereed Scanned Article (GIF)
· References in the article
· Citations to the Article (110) (Citation History)
· Refereed Citations to the Article
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Sunspots and the physics of magnetic flux tubes. IX - Umbral dots and longitudinal overstability
Authors:
Parker, E. N.
Affiliation:
AA(Chicago, University, Chicago, Ill.)
Publication:
Astrophysical Journal, Part 1, vol. 234, Nov. 15, 1979, p. 333-347. (ApJ Homepage)
Publication Date:
11/1979
Category:
Solar Physics
Origin:
STI
NASA/STI Keywords:
Magnetic Flux, Magnetohydrodynamic Stability, Sunspots, Umbras, Dynamic Stability, High Temperature Gases, Longitudinal Stability, Magnetohydrodynamic Waves, Perturbation Theory, Solar Magnetic Field
DOI:
10.1086/157501
Bibliographic Code:
1979ApJ...234..333P

Abstract

The dynamical properties of the sunspot field and of a column of hot gas confined by such a vertical magnetic field are examined in order to understand the umbral dot within the context of the magnetic sunspot structure. Attention is given to the conditions necessary for gas intrusion, longitudinal as well as convective overstability, the growing modes, and the even mode. With the hypothesis that the subsurface magnetic field of a sunspot splits into many separate flux tubes with field-free gas between, it is suggested that the field-free columns occasionally punch their way up through the overlying magnetic field to the surface, appearing there as the bright, field-free umbral dots. Effects fostering the phenomenon are also discussed, that is, the enhanced temperature of a column of rising gas, the strongly reduced overhead magnetic pressure, and the initiated upward intrusion; these effects are illustrated with examples.

Printing Options

Print whole paper
Print Page(s) through

Return 600 dpi PDF to Acrobat/Browser. Different resolutions (200 or 600 dpi), formats (Postscript, PDF, etc), page sizes (US Letter, European A4, etc), and compression (gzip,compress,none) can be set through the Printing Preferences



More Article Retrieval Options

HELP for Article Retrieval


Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)

  New!

Find Similar Abstracts:

Use: Authors
Title
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints