✦ LIBER ✦

Fluctuations of brightness and vertical velocity at various heights in the photosphere

✍ Scribed by Richard C. Canfield; J. P. Mehltretter

Publisher: Springer
Year: 1973
Tongue: English
Weight: 725 KB
Volume: 33
Category: Article
ISSN: 0038-0938
DOI: 10.1007/bf00152375

No coin nor oath required. For personal study only.

✦ Synopsis

In a spectrogram of exceptionally high spatial resolution, brightness and velocity fluctuations in seven weak to medium-strong Fe I lines have been measured and analyzed. Heights of formation of these lines have been computed using the Harvard-Smithsonian Reference Atmosphere (Gingerich et al., 1972), taking into account departures from LTE.

The results show that granular velocity fluctuations decrease with increasing height up to the vicinity of the temperature minimum. If extrapolated downward to the height of formation of the continuum, the rms velocity fluctuation is 0.8 km s -1 with an estimated error of :L0.2 km s -1.

The correlation of continuum brightness fluctuations with velocity fluctuations decreases rapidly with height, and even becomes slightly negative at h > 160 km. This finding is consistent with the picture of the granulation consisting of convective elements overshooting into a stable atmosphere. * On leave from Fraunhofer Institut, Freiburg, F.R.G.

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