Correlation lifetimes of quiet and magnetic granulation from the SOUP (Solar Optical Universal Polarimeter) instrument on Spacelab 2

Technical Report · Sat Oct 01 00:00:00 EDT 1988

OSTI ID:5440043

Title, A; Tarbell, T; Topka, K; Acton, L; Duncan, D

The flight of the Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 allowed the collection of time sequences of diffraction-limited (0.5 arc second) granulation images with excellent pointing (0.003 arc second jitter RMS) and freedom from the distortion that plagues ground-based images. The solar 5 minute oscillations are clearly seen in the data. Using Fourier transforms in the temporal and spatial domain, the authors show that these dominate the autocorrelation lifetime in magnetic regions. When the oscillations are removed the autocorrelation lifetime is found to be 410 and 890 seconds, respectively, in quiet and magnetic regions. In quiet areas exploding granules are common. It is hard to find that neither explodes nor is unaffected by a nearby explosion. A significant fraction of granule lifetimes are terminated by nearby explosions. Local correlation-tracking techniques are used to measure horizontal displacements, and thus transverse velocities, in the intensity field. In the quiet sun it is possible to detect both super- and mesogranulation. Horizontal velocities are as great as 1000 m/s quiet sun, and the average velocity is 400 m/s. In magnetic regions, horizontal velocities are much less, about 200 m/s. These flows effect the measured lifetime. A lower limit to the lifetime in quiet and magnetic sun is estimated to be 440 and 950 seconds respectively.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 5440043
• Report Number(s): AD-A-211361/1/XAB; AFGL-TR-89-0204
• Resource Relation: Other Information: Pub. in Astro. Lett. and Communications, Vol. 27, No. 3, 141-149(Oct 1988)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
POLARIMETERS
SOLAR ACTIVITY
OSCILLATIONS
SOLAR GRANULATION
CORRELATIONS
FOURIER TRANSFORMATION
MAGNETIC FIELDS
PHOTOSPHERE
RESOLUTION
SUN
ATMOSPHERES
INTEGRAL TRANSFORMATIONS
MAIN SEQUENCE STARS
SOLAR ATMOSPHERE
STARS
TRANSFORMATIONS
640104* - Astrophysics & Cosmology- Solar Phenomena