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Flare induced penumbra formation in the sunspot of NOAA 10838

Published online by Cambridge University Press:  26 August 2011

Sreejith Padinhatteeri  and
Sankarasubramanian K.
Sreejith Padinhatteeri
Affiliation:
Space Astronomy Group, ISRO Satellite Centre, Bangalore, India - 560017 email: [email protected], [email protected] Dept. of Physics, University of Calicut, Kerala, India.
Sankarasubramanian K.
Affiliation:
Space Astronomy Group, ISRO Satellite Centre, Bangalore, India - 560017 email: [email protected], [email protected]
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Abstract

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We have observed formation of penumbrae on a pore in the active region NOAA10838 using Dunn Solar Telescope at NSO, Sunpot, USA. Simultaneous observations using different instruments (DLSP, UBF, Gband and CaK) provide us with vector magnetic field at photosphere, intensity images and Doppler velocity at different heights from photosphere to chromosphere. Results from our analysis of this particular data-set suggests that penumbrae are formed as a result of relaxation of magnetic field due to a flare happening at the same time. Images in Hα show the flare (C 2.9 as per GOES) and vector magnetic fields show a re-orientation and reduction in the global α value (a measure of twist). We feel such relaxation of loop structures due to reconnections or flare could be one of the way by which field lines fall back to the photosphere to form penumbrae.

Keywords

Sunspotpenumbraflare
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S273: The Physics of Sun and Star Spots , August 2010 , pp. 303 - 307
Copyright
Copyright © International Astronomical Union 2011

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