EDP Sciences
Free access
Volume 395, Number 1, November III 2002
Page(s) 293 - 296
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20021355

A&A 395, 293-296 (2002)
DOI: 10.1051/0004-6361:20021355

An interpretation of the $\vec{I-V}$ phase background based on observed plasma jets

P. F. Moretti1, A. Cacciani2, A. Hanslmeier3, M. Messerotti4, W. Otruba5, W. Pötzi5 and A. Warmuth3

1  I.N.A.F., Osservatorio Astronomico di Capodimonte, Via Moiarello 16, 80131 Napoli, Italy
2  Department of Physics University of Rome, P.le A. Moro 2, 00185 Rome, Italy
3  Institute of Geophysics, Astrophysics and Meteorology of the University of Graz, Universitaetsplatz 5, 8010 Graz, Austria
4  I.N.A.F., Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy
5  Kanzelh $\ddot{\rm
o}$ he Solar Observatory, 9521 Treffen, Austria

(Received 13 November 2001 / Accepted 4 September 2002)

The presence of a solar background in the phase difference between the intensity and velocity ( I-V) p-mode oscillation signals recently has been interpreted in terms of downflows due to convection (Skartlien & Rast 2000) or due to chromospheric explosive events (Moretti et al. 2001a). In support of the latter, we present I and V characteristics of impulsive brightenings observed in the NaI D lines, show that these reproduce the frequency dependence of the I-V modulation background, and show that explanations invoking more frequently occurring phenomena such as seismic events are not likely in low- l modulation data.

Key words: Sun: oscillations -- Sun: flares

Offprint request: P. F. Moretti, moretti@na.astro.it

© ESO 2002