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New ideas about granulation based on data from the solar optical universal polarimeter instrument on Spacelab 2 and magnetic data from big bear solar observatory

Title, A. M. and Tarbell, T. D. and Topka, K. P. and Shine, R. A. and Simon, G. W. and Zirin, H. (1987) New ideas about granulation based on data from the solar optical universal polarimeter instrument on Spacelab 2 and magnetic data from big bear solar observatory. In: Solar and Stellar Physics. Lecture Notes in Physics. No.292. Springer-Verlag , Berlin, pp. 173-186. ISBN 978-3-540-18678-6.

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The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected time sequences of diffraction limited (0.5 are second) granulation images with excellent pointing (.003 arc seconds) and freedom from the distortion that plagues groundbased images. The solar 5 minute oscillations are clearly seen in the data. Using Fourier transforms in the temporal and spatial domains, we have shown that oscillations have an important effect on the autocorrelation (AC) lifetime. When the oscillations are removed the autocorrelation lifetime is found to increase from 270 seconds to 410 and 890 seconds in quiet and magnetic regions, respectively. Exploding granules are common and it is hard to find a granule that neither explodes nor is unaffected by an nearby explosion. We speculate that a significant fraction of granule lifetimes are terminated by nearby explosions. Via local correlation tracking techniques we have been able to measure horizontal displacements, and thus transverse velocities, in the intensity field. It is possible to detect both super and mesogranulation. Horizontal velocities are as great as 1000 m/s in quiet sun and the average velocity is 400 m/s and 100 m/s in quiet and magnetic sun, respectively. These flow fields affect the measured AC lifetimes. After correcting for steady flow, we estimate a lower limit to the lifetime in quiet and magnetic sun to be 440 and 950 seconds, respectively. The SOUP flow fields have been compared with carefully aligned magnetograms taken at the Big Bear Solar Observatory (BBSO) before, during, and after the SOUP images. The magnetic field is observed to exist in locations where either the flow is convergent or on the boundaries of the outflow from a flow cell center. Streamlines calculated from the flow field agree very well with the observed motions of the magnetic field in the BBSO magnetogram movies.

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Additional Information:© Springer-Verlag 1987. Special thanks are extended to the crew of Spacelab 2 and the controllers and planners on the ground who worked so hard to get the observations described here on the extension day of the mission. The SOUP instrument was built by and under the direction of Mike Finch, Gary Kelly, Roger Rehse, and Ralph Reeves. The SOUP experiment was supported by NASA under contract NASS-23805. The image processing developments using laser optical disks have been supported by Lockheed Independent Research funds.
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Lockheed Independent Research FundUNSPECIFIED
Subject Keywords:Flow Field, Magnetic Region, Solar Granulation, Minute Oscillation, Spatial Autocorrelation Function
Series Name:Lecture Notes in Physics
Issue or Number:292
Record Number:CaltechAUTHORS:20211104-024607244
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111739
Deposited By: Rebecca Minjarez
Deposited On:04 Nov 2021 20:39
Last Modified:04 Nov 2021 20:39

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