Some properties of velocity fields in the solar photosphere

✍ Scribed by Franz-Ludwig Deubner

• Publisher: Springer
• Year: 1972
• Tongue: English
• Weight: 653 KB
• Volume: 22
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00148695

✦ Synopsis

Photoelectric measurements of photospheric velocity fields have been carried out with the Sacramento Peak Doppler Zeeman Analyzer. Emphasis was given to long periods and low spatial wavenumbers in deep photospheric layers, where the 5-rain oscillations are less dominant.

Multiple or double peaks cannot be detected in power spectra of the 5-min oscillations, provided that a sufficient number of physically independent points on the solar surface are observed.

The most frequent 'wave-numbers' in the spectra of 5-min oscillations (as well as of the low frequency field) agree with those derived from a model assuming statistically independent oscillators of 10" to 20" diameter. These two velocity fields are anti-correlated spatially.

Kinetic power in the 20-to-50-min range of periods is closely linked to brightness changes in the same layer, an increase of brightness lagging about 250 sec behind rising motion. Granules can be excluded as a possible source for the appearance of low frequency flow patterns. Different explanations are suggested.