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Astron. Astrophys. 322, 653-658 (1997)


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Magnetic and velocity field in association with Ellerman bombs

H.C. Dara 1, C.E. Alissandrakis 2, Th.G. Zachariadis 1 and A.A. Georgakilas 3

1 Research Center for Astronomy and Applied Mathematics, Academy of Athens, 14 Anagnostopoulou St., GR-10673 Athens, Greece
2 Section of Astro-Geophysics, Department of Physics, University of Ioannina, GR-45110 Ioannina, Greece
3 Astronomical Institute, National Observatory of Athens, P.O. Box 20048, GR-11810 Athens, Greece

Received 22 December 1995 / Accepted 20 June 1996

Abstract

We present two dimensional maps of the longitudinal magnetic field, obtained in the Ca I 6103 Å line, as well as line of sight velocity maps in H [FORMULA] for an active region. The observations were obtained with the Tower telescope of the Sacramento Peak Observatory and the Universal Birefrigent Filter, with circular polarization measurements. The comparison of the photographs in the wing of H [FORMULA], where the Ellerman bombs (EBs) are best observed, with the corresponding magnetic maps shows that very few EBs are associated with small scale magnetic elements, while the great majority, especially the brighter ones, appear at the boundaries of magnetic features. The comparison of EBs with the velocity maps in the wings of H [FORMULA] shows that most of them coincide with blue wing intensity excess; near the brightest EBs ascending motions are observed. We also found a very good coincidence of EBs with photospheric facular granules.

Key words: Sun: magnetic fields – sunspots – polarization

Send offprint requests to: H.C. Dara

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

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