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Titolo:
Nonlinear sunspot transition region oscillations in NOAA 8378
Autore:
Brynildsen, N; Kjeldseth-Moe, O; Maltby, P; Wilhelm, K;
Indirizzi:
Univ Oslo, Inst Theoret Astrophys, N-0315 Oslo, Norway Univ Oslo Oslo Norway N-0315 Inst Theoret Astrophys, N-0315 Oslo, Norway Max Planck Inst Aeron, D-37191 Katlenburg Linden, Germany Max Planck Inst Aeron Katlenburg Linden Germany D-37191 Linden, Germany
Titolo Testata:
ASTROPHYSICAL JOURNAL
fascicolo: 2, volume: 517, anno: 1999,
parte:, 2
pagine: L159 - L162
SICI:
0004-637X(19990601)517:2<L159:NSTROI>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOLAR;
Keywords:
Sun : oscillations; Sun : transition region; Sun : UV radiation; sunspots;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
13
Recensione:
Indirizzi per estratti:
Indirizzo: Brynildsen, N Univ Oslo, Inst Theoret Astrophys, POB 1029 Blindern, N-0315Oslo, Norway Univ Oslo POB 1029 Blindern Oslo Norway N-0315 Oslo, Norway
Citazione:
N. Brynildsen et al., "Nonlinear sunspot transition region oscillations in NOAA 8378", ASTROPHYS J, 517(2), 1999, pp. L159-L162

Abstract

Observations obtained with the Solar and Heliospheric Observatory, joint observing program for velocity fields in sunspot regions are used to study the 3 minute transition region oscillations above four sunspots. Here we report mainly on the results obtained for NOAA 8378, based on simultaneous recordings of the transition region lines O v lambda 629 and N v lambda lambda1238, 1242 and the chromospheric Si II lambda 1260 line with the Solar Ultraviolet Measurements of Emitted Radiation instrument. The 3 minute transition region oscillations in NOAA 8378 occur mainly above the umbra and show (1) larger peak line intensity amplitudes than reported before, (2) clear signs of nonlinearities, (3) significant oscillations in line width, (4) maxima in peak line intensity and maxima in velocity directed toward the observer that are nearly, but not exactly in phase, and (5) a clear connection to the oscillations in the sunspot chromosphere. The suggestion that the waves are upward-propagating acoustic waves is confronted with the observations by a simple test.

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Documento generato il 22/10/20 alle ore 08:03:17