2001-2003
INTAS, Ref. No: 543, Project Title: "Study of MHD Oscillations in Solar Active Regions
Using Radio Observations"
Study of MHD Oscillations in Solar Active Regions Using Radio Observations.
2002 - 2004
Russian-Chinese projects of RFFR, Ref. No: 02-02-39030, Project Title: "Researches of
the sporadic phenomena in microwave radiation of the Sun with high spatial, temporary
and frequency resolution"
The purpose given project is a study of the sporadic phenomena in mcw-radiarion in solar
flare. The base of the project is analysis of the original observations of the mcw sources with
fine time structure on frequency 5,7 GHz (Siberian Solar Radio Telescope), data from
Nobeyama Radioheliograph 17 GHz, images in soft and hard x-ray radiation (the orbital
telescopes Yohkoh) and temporary profile integral flux hard x-ray radiation with millisecond
temporal resolution (CGRO/BATSE). The important component part of project is an analysis of
the simultaneous observations dynamic spectrum microwave emission in the range of 1,0 - 7,6
GHz in Beijing Astronomical Observatory. It Is expected, first, research the condition in flare
area, under which reveals itself the fine temporary structure; secondly, define the
parameters electron flow generating microwave radiation and, in-third, study the physical
mechanisms intensive oscillation in microwave range. Main goal of the project - study
information potential of the observations of the fine time structure for determination of the
features of the elementary acts energy release in solar flare..
2003 - Atual
Russian projects of RFFR, Ref. No: 03-02-16229, Project Title: "Diagnostics of processes
energy release of solar flares on microwave radiation"
Taking advantage of the financial support by the RFBR grant, the project participants solved
the task of recording at the both arms of the SSRT and archiving one-dimensional radio
distribution of the brightness temperature over the Sun stepped by 14 ms. A series of new
events containing sub-second microwave emission pulses (SSP) was recorded. Starting from
2000, time profiles are transferred to the Web site of the Radio Astrophysical Observatory. An
important progress in the study of fine time structured microwave emission of solar flares was
achieved with the start of operation of a spectropolarimeter set in China with time resolution
better than 20 ms, covering the working frequency of the SSRT (5.7 GHz). For the first time,
a data set was composed combining high temporal, spatial, and spectral resolution. This opens
opportunities of identification of their emission mechanisms and, consequently, their use for
diagnostics of parameters of electron beams and acceleration sites. Comparisons of the
microwave spatial structure reflecting propagation of accelerated electrons with
magnetograms and flare images obtained in other spectral domains made possible to build
scenarios for a range of solar flares. A theoretical analysis of properties of microwave fine
time structures was carried out taking into account inhomogeneities of plasma density in
emitting regions. Inhomogeneity structure was shown to be able to determine the character
of the emission. An important part of the project is development of technical solutions of the
upgrading problem of the unique Russian instrument, SSRT. Proposals to reconstruct SSRT into
6-frequency radioheliograph of 2 to 9 GHz range were approved by master scientists of
Russia, Japan, and China. .
2003 - Atual
Russian projects of RFFR, Ref. No: 03-02-16591, Project Title: "Diagnostics of physical
conditions and magnetic configurations in solar flares"
The scientific goal of the project is the research of a nature of solar flares on the basis of the
joint analysis data of a number modern ground and satellite solar instruments. A basis make the
radio images of the Sun received on two frequencies Nobeyama radiogeliograph. Satellite and
ground observation of solar flares in last decade have given huge observant material in various
frequency bands of solar emission, however till now it is not clear, in the open or closed
magnetic configurations there are flares. The distribution is established also, that distribution
of magnetic fields on height in a solar corona more uniform, than was considered earlier. Any
of existing models does not explain the forms of the coronal loops. A number of questions
about flare configurations, localization of acceleration areas, ratio thermal and not thermal
processes, ratio of flares and CME is not clear. The main method of researches - analysis
microwave data on as a minimum two frequencies together with the data both hard and soft
x-ray and extreme ultra-violet ranges, that allows to investigate structure flare areas, to
allocate thermal and not thermal processes, to estimate physical conditions in burst areas. The
second method consists in study quasi-periodical pulsations, in a number of events observable
in emission of burst sources. Quasi-periodical phenomenon give additional information on
physical conditions in flare areas. .
2001 - 2003
Russian projects of RFFR, Ref. No: 01-02-16290, Project Title: "Quasiperiodical
variation and intensity fluctuation of microwave emission of solar spots"
The purpose of the project is the research of a nature quasiperiodical variation of the
microwave emission from the solar spots on the basis joint analysis of sets 2D radio maps
obtained on SSRT with cadence ~ 2 min and 1D scans with 14 ms time resolution, both number
of modern ground and satellite solar instruments. The satellite and ground observation of
emission from solar spots of last decade given a huge observant material in various frequency
bands of solar emission, however till now it is not clear, what is mechanism generation of
quasiperiodical oscillation of radio emission in spots. A number of questions about
configurations of magnetic fields, localization of areas of generation, ratio of flares and
increasing of variation component is not clear. The basic method of researches - analysis of
the microwave data SSRT together with the data of hard and soft x-ray and extreme
ultra-violet frequency bands, that allows to investigate structure of spots before and during
start of variation emission and estimate physical conditions in them. .
1996 - 1998
Russian projects of RFFR, Ref. No: 96-02-16644, Project Title: "The microwave source
above the inversion line as an indicator of the solar flare build-up phase "
The basic goal of presented research is search in structure microwave emission of the active
areas (AR) precursor of powerful flares, which are observed as a bursts of radio and X-ray
radiation. As have shown results of researches, such predicters are long-lived, the compact
enough microwave sources, which lies on inversion line of a magnetic field of active area and
ontained name NLS (Neutral Line associated Sources). The analysis of characteristics these
sources on the basis data Siberian Solar Radio Telescope (SSRT) has shown the following: NLS
- hardly probable is a unique detail in spatial structure of microwave emission of active
region, which occurrence precedes (day, hours) the beginning of powerful X-ray flare. The
growing reliance reliability of this result allows to think about relation of the physical reasons,
bringing in occurrence NLS and the subsequent development burst process in magnetosphere
of active region..
2000 - 2002
Russian projects of RPFR, Ref. No: 00-02-16456, Project Title: "Observing and
researching current sheets in active regions of solar atmosphere on basis data from SSRT
and Nobeyama radioheliograph"
The evolution of the solar active region (AR) NOAA~7321 in which appeared a so-called
Neutral Line Associated Sources(NLS)is studied on the basis of data of the Siberian Solar Radio
Telescope, Nobeyama Radioheliograph, Yohkoh/SXT and magnetograms. We provide physical
interpretation of the NLS in terms of topological magnetic reconnection model in a quadrupole
magnetic configuration and discuss their relation to the evolution of the active region. Two
kinds of the NLS were observed. One of them, ``rising NLS'', was found in the growth stage.
The other was ``stationary NLS'' detected in the maximal stage of the AR. Their presence was
associated with substantial expansion of the active region's magnetosphere and accompanied
by gradual development of spine-like structures visible in soft X-rays before homologous
long-duration arcade flares. We suggest that the rising NLS corresponded to a fragment of a
``horizontal'' current sheet moving upward. Bright X-ray spines were boundaries of that
current sheet. Almost all bursts observed during the AR growth stage which accompanied class
C and M flares occurred in the rising NLS. Formation of magnetic X-point singularities is
believed to be responsible for the low-lying NLS. Reversal of circular polarization due to the
effect of radio wave propagation was detected in that NLS on the limb. The initial stage of
the microwave burst of the long-duration X9 class flare on Nov.~2, 1992 occurred in this NLS.
We also revealed observational manifestations of the presence of "vertical" current sheet in
the spatial structure of this NLS before the flare. .
2000 - 2002
Russian projects of RPFR, Ref. No: 00-02-16819, Project Title: "Research of pulse flows
accelerated electrons of solar flares in the low corona"
84 events with the fine structure of microwave emission were recorded by the Siberian solar
radio telescope (SSRT) for three last years. The special interest calls a number of events
(about 30 %); in which subsecond pulses with a degree of polarization up to 100% for the first
time were recorded. For several events the source locations of microwave subsecond pulses
were observed simultaneously in two frequencies. The catalog of SSRT data with time profiles
is shown in the web-site www.eastsib.ru/~fastevents/. For a significant part of these events
the dynamic spectra from Chinese polarimeters in the frequency band 1,0 - 7,6 GHz with the
temporary resolution down to 5 ms were obtained. The simultaneous data on a microwave
radiation on 17 GHz (Nobeyama Radioheliograph, Japan), X-ray, and Ultra-Violet radiations are
assembled also. Main mechanisms of their generation and plasma parameters in sources of
their generation were determined. For some events source positions were located relative to
the energy released regions of solar flares. As a result of investigation of spatial structure and
dynamics of solar flares in microwaves the fruitfulness of solar images to determine the flare
magnetic field topology is shown, at least, for high-power geoeffective events. The high
degree of correlation between a flare power and the response on them in the full electron
contents in the Earth ionosphere was detected. It has important for applications. The analysis
of the subsecond pulse generation mechanisms for real conditions of inhomogeneous (as in
density, as in magnetic field) solar atmosphere was carried out. It allows to develop the
quantitative description of temporal and frequency futures of fine temporary structure of
microwave emission. .
2001 - Atual
International projects of BDA system, Project Title: "Brazilian Decimetric Radio
Telescope (BDA system)"
The Brazilian Decimetric Array (BDA), under development, will have high spatial and time
resolutions of ~ 5 sec of arc at 5.0 GHz and 100 ms respectively. It is planed to employ modern
technology at low cost. The BDA will have the capability to observe solar and non-solar
phenomena in the following radio protected bands: 1.2 - 1.7, 2.7 and 5.0 GHz. The sensitivity
estimates show that the BDA will have rms. sensitivity of 3 mJy at 21 cm for a system
temperature of 50 K, using low noise amplifiers. The final version of the BDA will be an
interferometer array consisting of 38 parabolic antennas of 5 meters diameter with a compact
T shaped array at the center having 32 antennas .The array will be located at Cachoeira
Paulista. PHASE I five-element interferometer will be developed at INPE using a 5-meter
diameter parabolic dish with alt-azimuth mount and complete tracking capability. The PLO
receiver operating initially in the frequency range of 1.2 - 1.7 GHz will be also developed.
The main aim of this phase is to optimize the cost of the mechanical and electronics
subsystems of the BDA. Various engineering tests of the sub systems will be carried out so as
to optimize the cost and the performance of the overall system. Then the interferometer will
be moved to Cachoeira Paulista. The distances of the antennas will be changed so as simulate
the distances of BDA phase II. In this case spatial resolution will be ~3 x 4 minute of arc.
PHASE II 21 antennas will be laid out over the distance of 256 meters in the east-west
direction and 11 antennas will be laid out over a distance of 144 meters in the southern
direction, in a T format. The frequency range will be increased to 1.2- 1.7, 2.7 and 5.0 GHz.
PHASE III mainly spatial resolution will be increased. Base lines will be increased in both in
east-west and south directions to 2.5 km and 1.25 km .
Research projects