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Improved methods for the measurement and analysis of stellar magnetic fieldsThe paper presents several improved methods for the measurement of magnetic fields on cool stars which take into account simple radiative transfer effects and the exact Zeeman patterns. Using these methods, high-resolution, low-noise data can be fitted with theoretical line profiles to determine the mean magnetic field strength in stellar active regions and a model-dependent fraction of the stellar surface (filling factor) covered by these regions. Random errors in the derived field strength and filling factor are parameterized in terms of signal-to-noise ratio, wavelength, spectral resolution, stellar rotation rate, and the magnetic parameters themselves. Weak line blends, if left uncorrected, can have significant systematic effects on the derived magnetic parameters, and thus several methods are developed to compensate partially for them. The magnetic parameters determined by previous methods likely have systematic errors because of such line blends and because of line saturation effects. Other sources of systematic error are explored in detail. These sources of error currently make it difficult to determine the magnetic parameters of individual stars to better than about + or - 20 percent.
Document ID
19880036606
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Saar, Steven H.
(Joint Institute for Laboratory Astrophysics Boulder, CO, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 324
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
88A23833
Funding Number(s)
CONTRACT_GRANT: NAG5-82
CONTRACT_GRANT: NGL-06-003-057
Distribution Limits
Public
Copyright
Other

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