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Astronomy & Astrophysics manuscript no. 0503 August 11, 2004 (DOI: will be inserted by hand later)
 

Summary: Astronomy & Astrophysics manuscript no. 0503 August 11, 2004
(DOI: will be inserted by hand later)
Transition region small-scale dynamics as seen by SUMER on
SOHO
L. Teriaca 1 , D. Banerjee 2 , A. Falchi 3 , J. G. Doyle 4 and M. S. Madjarska 5
1 Max-Planck-Institut fur Sonnensystemforschung ? , Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
2 Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India
3 INAF-Osservatorio Astro sico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
4 Armagh Observatory, College Hill, Armagh BT61 9DG, UK
5 Mullard Space Science Laboratory, University College London, Holmbury St Mary RH5 6NT, UK
Abstract. High spectral, spatial and temporal resolution UV observations of the quiet Sun transition region show
a highly structured and dynamical environment where transient supersonic ows are commonly observed. Strongly
non-Gaussian line pro les are the spectral signatures of these ows and are known in the literature as explosive
events. In this paper we present a high spatial resolution ( 1 00 ) spectroheliogram of a 273 00  291 00 area of the
quiet Sun acquired with SUMER/SOHO in the O vi spectral line at 103.193 nm. The extremely high quality of
these observations allows us to identify tens of explosive events from which we estimate an average size of 1 800 km
and a birthrate of 2 500 s 1 over the entire Sun. Estimates of the kinetic and enthalpy uxes associated with these
events show that explosive events are not important as far as solar coronal heating is concerned. The relationship
with the underlying photospheric magnetic eld is also studied, revealing that explosive events generally occur
in regions with weak (and, very likely, mixed polarity) magnetic ux. By studying the structure of upward and

  

Source: Armagh Observatory

 

Collections: Physics