Waves in the solar transition region

被引:36
作者
Doyle, JG [1 ]
Van den Oord, GHJ
O'Shea, E
Banerjee, D
机构
[1] Armagh Observ, Armagh BT61 9DG, North Ireland
[2] Sterrekundig Inst, NL-3508 TA Utrecht, Netherlands
关键词
D O I
10.1023/A:1005078018623
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The power spectra for line intensities of several lines formed in the upper transition region around 100 000 to 250 000 K are presented. A period of similar to 5 min is clearly present in lines due to O III, O IV, and O V. In one dataset a period approaching 10 min is present for similar to 40 min. The size of the emitting features is limited to similar to 7 are sec squared. In all datasets examined, there is excess power below 4 mHz everywhere along the slit, although the observed periods do not always come from the most intense regions. In similar to 40% of instances clear periods are observable in the 2-5 mHz range with the largest power peak at 3.0 mHz. In all regions, the 5.0 mHz power peak is smaller. For the frequencies investigated there are no significant time delays in any of the datasets examined. This finding may not be entirely unexpected as the formation temperatures of O III (similar to 100 000 K) and O V (similar to 250 000 K) may be too close in order to result in an observable phase shift. The observations are discussed in terms of trapped magnetic modes below the transition region and resonant absorption of MHD waves. For resonant absorption we derive from the observed period of 5 min and the observed extent of the structure a typical magnetic field strength of about 2 G. This value is in good agreement with results from MDI for quiet-Sun regions. Our results seem to imply that resonant waves can play a role in the heating of the quiet Sun. We discuss the effect of observing without tracking on the power spectrum and show that the effect is small.
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页码:51 / 71
页数:21
相关论文
共 25 条
[1]   CHROMOSPHERIC OSCILLATIONS OBSERVED WITH OSO-8 .4. POWER AND PHASE SPECTRA FOR C-IV [J].
ATHAY, RG ;
WHITE, OR .
ASTROPHYSICAL JOURNAL, 1979, 229 (03) :1147-1162
[2]  
ATHAY RG, 1979, ASTROPHYS J SUPPL S, V39, P333, DOI 10.1086/190574
[3]   Effect of Newtonian cooling on waves in a magnetized isothermal atmosphere [J].
Banerjee, D ;
Hasan, SS ;
ChristensenDalsgaard, J .
SOLAR PHYSICS, 1997, 172 (1-2) :53-60
[4]   THE INFLUENCE OF A VERTICAL MAGNETIC-FIELD ON OSCILLATIONS IN AN ISOTHERMAL STRATIFIED ATMOSPHERE .2. [J].
BANERJEE, D ;
HASAN, SS ;
CHRISTENSENDALSGAARD, J .
ASTROPHYSICAL JOURNAL, 1995, 451 (02) :825-842
[5]  
Baudin F, 1996, ASTRON ASTROPHYS, V314, pL9
[6]  
DAME L, 1984, ASTRON ASTROPHYS, V130, P331
[7]  
Doyle JG, 1997, ASTRON ASTROPHYS, V327, P365
[8]   Coronal line-width variations [J].
Doyle, JG ;
Banerjee, D ;
Perez, ME .
SOLAR PHYSICS, 1998, 181 (01) :91-101
[9]   The coronal diagnostic spectrometer for the solar and heliospheric observatory [J].
Harrison, RA ;
Sawyer, EC ;
Carter, MK ;
Cruise, AM ;
Cutler, RM ;
Fludra, A ;
Hayes, RW ;
Kent, BJ ;
Lang, J ;
Parker, DJ ;
Payne, J ;
Pike, CD ;
Peskett, SC ;
Richards, AG ;
Culhane, JL ;
Norman, K ;
Breeveld, AA ;
Breeveld, ER ;
ALJanabi, KF ;
Mccalden, AJ ;
Parkinson, JH ;
Self, DG ;
Thomas, PD ;
Poland, AI ;
Thomas, RJ ;
Thompson, WT ;
KjeldsethMoe, O ;
Brekke, P ;
Karud, J ;
Maltby, P ;
Aschenbach, B ;
Brauninger, H ;
Kuhne, M ;
Hollandt, J ;
Siegmund, OHW ;
Huber, MCE ;
Gabriel, AH ;
Mason, HE ;
Bromage, BJI .
SOLAR PHYSICS, 1995, 162 (1-2) :233-290
[10]   RESONANT HEATING - AN INTERPRETATION OF CORONAL LOOP DATA [J].
HOLLWEG, JV ;
STERLING, AC .
ASTROPHYSICAL JOURNAL, 1984, 282 (01) :L31-L31