Astronomy and Astrophysics – Astronomy
Scientific paper
May 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011spd....42.1716h&link_type=abstract
American Astronomical Society, SPD meeting #42, #17.16; Bulletin of the American Astronomical Society, Vol. 43, 2011
Astronomy and Astrophysics
Astronomy
Scientific paper
The intrinsic rotation of sunspots is considered to play a role in the magnetic energy buildup leading to solar eruptions. Much of sunspot intrinsic rotational measurements are made from photospheric observations via white-light imaging and refers to rotation of the photospheric layers. This paper presents a pilot project to investigate measures of intrinsic sunspot rotations at both the photosphere (true-continuum) and chromosphere (H-alpha) in an effort to understand their coupling in these layers.
The data used in this research are obtained from the USAF/AFRL/NSO Improved Solar Observing Optical Network (ISOON) prototype telescope at the National Solar Observatory, Sunspot, New Mexico. ISOON images from 2003 October 27-29 include NOAA active regions 10484, 10486, 10487, 10488, 10490, 10491, and 10492. These active regions, during the mentioned time period, were a source of intensive solar eruptions and include a 4B/X17.2-class solar flare in NOAA Active Region 10486 (Ambastha 2007; Kazachenko et al., 2010).
For each sunspot within an active region, a circular aperture is chosen to enclose the sunspot. The aperture is centered on the umbra and the sunspot is "uncurled” into a two-dimensional plot of radial distance, in pixels, versus angular distance, in degrees. This procedure follows the technique of Balasubramaniam (2002) and Brown et al. (2003) and will yield intrinsic sunspot rotational velocities through time for variable distances from the umbral center. We present our initial comparisons of photospheric and chromospheric rotational characteristics, the extent of coupling between the photosphere and chromosphere, and rotational characteristics as a function of sunspot size, age, solar latitude, and classification. Determining the rotational nature of a large number of sunspots as a function of various sunspot characteristics can lead to a greater understanding of the effects of intrinsic sunspot rotations on the occurrences of solar flares.
Balasubramaniam K.
Hardersen Paul Scott
Shkolyar S.
Zak B.
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