Temporal and spatial fluctuations in strengths and widths of C IV and Si II lines observed with OSO 8

Journal Article · Fri Aug 15 04:00:00 EDT 1980 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/158234· OSTI ID:7094991

Athay, R G; White, O R

Time series of profiles for lines of C IV lambda1548, and Si II lambda1816.93, 1817.45, observed with an effective aperture of 2'' x 20'' and with time resolution less than 30 s are analyzed to determine the statistical properties of temporal and spatial fluctuations in line widths and strengths. Three classes of fluctuations with substantial amplitudes are evident in the data: (1) short term fluctuations with a characteristic fluctuation time near 5 minutes, (2) intermediate term fluctuations with a characteristic time of 30 minutes or longer, and (3) large scale spatial fluctuations associated with supergranule cell, network, and plage structure. For C IV the dominant fluctuations in line width are short term, whereas for Si II the dominant width fluctuations are intermediate term. Fluctuations in line strength for both C IV and Si II are appreciable on both short and intermediate term but are dominated by the large scale spatial structure. Ranges in line widths during 30 minute intervals average +- 15% in C IV and +- 12% in Si II, and they often exceed twice these values. Extreme ranges of full widths at half-maximum (FWHM) averaged for 30 minutes and over an area of 2'' x 20'' extend from 200 mA to 390 mA for C IV and from 75 mA to 175 mA for lambda1816.93 of Si II. Average FWHM values on the disk inside ..mu..=0.5 are 251 mA for C IV, 116 mA for lambda1816.93, and 98 mA for lambda1817.45.

• Research Organization: High Altitude Observatory, National Center for Atmospheric Research; and University of Colorado, Boulder
• OSTI ID: 7094991
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 240:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CARBON IONS
CHARGED PARTICLES
CHROMOSPHERE
FLUCTUATIONS
FUNCTIONS
IONS
LINE WIDTHS
MATHEMATICS
SILICON IONS
SOLAR ATMOSPHERE
SOLAR CORONA
SPECTRA
SPECTRAL FUNCTIONS
SPECTRAL SHIFT
STATISTICS
TIME-SERIES ANALYSIS
ULTRAVIOLET SPECTRA
VARIATIONS