v.v. smirnova 1 , v.g. nagnibeda 1 ,
DESCRIPTION
Simultaneous monitoring observations of solar active regions at millimeter wavelengths at radio telescopes RT-7.5 BMSTU (Russia) and RT-14 Metsahovi radio observatory (Finland). V.V. Smirnova 1 , V.G. Nagnibeda 1 , V.S. Ryzhov 2 , A.V.Zhiltsov 2 , A. Riehokainen 3 , J. Kallunki 3,4 - PowerPoint PPT PresentationTRANSCRIPT
Simultaneous monitoring observations of solar active regions at millimeter wavelengths at radio telescopes RT-7.5 BMSTU (Russia)
and RT-14 Metsahovi radio observatory (Finland)
V.V. Smirnova1, V.G. Nagnibeda1,
V.S. Ryzhov 2, A.V.Zhiltsov2, A. Riehokainen3, J. Kallunki3,4
1Astronomical Institute, Saint-Petersburg State University2Bauman Moscow State Technical University
3University of Turku (Finland)4Aalto University, Metsähovi Radio Observatory (Finland)
[email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Scientific mission of the project
Solar active regions (ARs) at millimeter wavelengths:
- quasiperiodic oscillations of ARs; - observational properties of millimeter bursts;
First results
New solar observations at millimeter wavelengths:
Simultaneous monitoring observations of solar active regions at 37, 93 and 140 GHz!
Goals:
1. The investigation of quasi-periodic oscillations of ARs at millimeter waves;
2. The interpretation of millimeter emissionproperties in solar flares.
RT-7.5: 93GHz (2'.5) and 140 GHz (1'.5); RT-14: 2-150 GHz, now: 37GHz (2'.4)
Background
The investigation of quasi-periodic oscillations of ARs at millimeter waves
Oscillating structures Characterize periods Notes
Prominences and filaments
15-20 min Gelfreikh et al., 2006
Plums 7-20 min Ofman, 2000
Spicules 5 min Scullion et al., 2009
Coronal loops 5 sec; 10-30 min Nakariakov and Stepanov, 2007
Sunspots 2 min – 160 min and more
Kostik, 2004; Gelfreikh, 2006
Because of instruments limitations and atmospheric fluctuations at mm waves, we decided to pay attention to long-period oscillations (>1 min).. Also, there is no clear interpretation of some long periods like 100 min.
First results
Long periods were found at the AR 11084 01.07.2010 (spots!): 20, 30, 100 minutes. The amplitude was different: at 37 GHz some oscillations had lower amplitude than at 93GHz.
We supposed, that 100 min. oscillations could be related to the large-scales motions of material above the spot region, or they could be some modes of more global oscillating processes in the spot.
We obtained two series of observations from the end of June to 31.08. 2010 and analyzed one of them with continuous wavelet transform (Morlet).
The interpretation of millimeter emission properties in solar flares
We analyzed few flare events by GOES class from M to X at microwave-millimeter wavelengths used NoRP data (1, 2, 3.75, 9.4, 17, 35, 80 GHz) with the mm emission excess and GOES 1-8A (for example 13.09.2005, X1.7). Light curves contained impulses and the background. The duration of impulses in the radio-burst light-curve ~ 20 s. In spectra:the maximum was shifted to short wavelengths; the spectral flattening was found – not like in classical gyro-synchrotron spectrum.
Because of the good known correlation of HXRs and millimeter light-curves, we supposed that the millimeter emission increasing at spectra is related to the injection of high-energetic electrons in the burst source. The same particles could involved in plasma heating processes and provide the shift of the fmax to high frequencies in microwave spectra. δ=2.16 (from the hxr spectrum), Ne ≈ 1.1*1011cm-3.
We found that in several events the increasing of the flux density in radio light-curves is coincide well with the GOES 1-8A light-curve, that give us the possibility to interpret the background of radio light-curve as a thermal component of the burst radio-emission. We obtained the spectra of the thermal component and estimated the emission measure and number of thermal electrons.
EM=5*1026;; Ne=7*108.
The interpretation of millimeter emission properties in solar flares
Summary:
The aim of this work is to provide simultaneous monitoring observations of quite active regions (QPO interpretation) and flares at millimeter waves (to obtain the detailed information about spectral properties). The estimation of the dependence of the flux density and the spectral index of non-thermal electrons for 3.2 and 2.2 mm shows that for existing of short mm gyro-synchrotron emission, the spectral index should be less then 4, so the spectrum should be hard.
We supposed that mm burst contains thermal and non-thermal components and it reflects in spectra. But the emission mechanism of bursts at mm waves could be not only gyro-synchrotron but some mechanisms could contribute in complex.
