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 (117) (Citation History)
· Refereed Citations to the Article
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Distribution of sunspot umbral areas - 1917-1982
Authors:
Bogdan, T. J.; Gilman, Peter A.; Lerche, I.; Howard, Robert
Affiliation:
AA(High Altitude Observatory, Boulder, CO), AB(High Altitude Observatory, Boulder, CO), AC(South Carolina, University, Columbia), AD(National Solar Observatory, Tucson, AZ)
Publication:
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 327, April 1, 1988, p. 451-456. (ApJ Homepage)
Publication Date:
04/1988
Category:
Solar Physics
Origin:
STI
NASA/STI Keywords:
Astronomical Photography, Solar Magnetic Field, Sunspots, Umbras, Magnetic Flux, Solar Spectra
DOI:
10.1086/166206
Bibliographic Code:
1988ApJ...327..451B

Abstract

Over 24,000 measurements of individual sunspot umbral areas taken from the Mount Wilson white-light plate collection covering the period 1917-1982 are used to determine the relative size distribution of sunspot umbras. In the range 1.5-141 millionths of a solar hemisphere, the sunspot umbral areas are found to be distributed lognormally. Moreover, the same distribution is obtained for all phases of the solar cycle (maximum, minimum, ascending, descending), as well as for various individual cycles, between 1917 and 1982. Both the mean and the geometric logarithmic standard deviation of this distribution appear to be intrinsically constant over the entire data set; only the number of spots exhibits the familiar solar cycle variations. If the observed lognormal umbral size distribution is not a particular attribute of the sunspot umbras but is instead of a more fundamental property of emerging magnetic flux, then the data would predict a maximum in the size spectrum of photospheric magnetic structures for flux tubes with radii in the range 500-800 km. The absence of solar cycle variations in the relative distribution of umbral areas and especially the lognormal character of this distribution may both argue for the fragmentation of magnetic elements in the solar envelope.

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)


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