National Academy of Science of Ukraine - Institute of Radio Astronomy (Ukraine)

Description: Institute of Radio Astronomy of National Academy of Sciences of Ukraine is the leader radio astronomical organization in Ukraine in study of low frequency decameter researches of different cosmic objects such as Sun, Jupiter, Saturn, flare stars, pulsars, supernova remnants, galaxies, quasars etc. Institute of Radio Astronomy has the largest in the world (effective area, 150 000sq. m, 2000 single dipoles) radio telescope in decameter range (10-30 MHz). Observations are carrying out from 1970. Scientists from Russia, France, Austria, Sweden, and India took part in observations on different scientific programs. Registered devices are under certain improvement. If in the beginning observations were conducted at 4-6 single different frequencies, in the end of 90th at 30 and 60 frequencies, now registration is realized in the continuous frequency band 10-30 MHz. At the moment new giant radio telescope GURT (Giant Ukrainian Radio Telescope) is being created on the new principles with effective area 1,000,000 sq.m and working frequency band 10-70 MHz. This project is financed by National Academy of Sciences of Ukraine. To the end of this year 10 sections of radio telescope (250 single dipoles) will be constructed. The first successful observations of different cosmic objects (including the Sun) were carried out. Principles and ideas of new giant radio telescope were being discussed at wide international participation (Holland, USA, France, Germany, Sweden, Austria, and Great Britain). Solar researches have been carried out from 70th of last century. If at the beginning solar observations were conducted at 4-6 single frequencies now we have 5 modern DSP (Digital Spectral Polarimeter) which give an opportunity to register radio emission in the wide frequency band 10-70 MHz with time and frequency resolution 1ms and 4 kHz and dynamic range 90 dB with 5 single beams.

The main scientific tasks considered with the solar group:

- observations and analysis of sporadic radio emission of the Sun at frequencies 10-70 MHz. The studied phenomena are Type III bursts, Type IIIb bursts, Type II bursts, Type IV bursts, drift pairs, solar S-bursts, spikes, bursts in absorption. Due to high time and frequency resolutions a fine time and frequency structure of these bursts succeeded to study.

- observations and analysis of the quiet Sun radio emission. These investigations allow considering the emissivity of solar corona at height up to 3 solar radii.

- heliographic observations of radio emission of the Sun. They give an opportunity to define the place of radio sources and their sizes.

- interpretations of sporadic solar radio emission on the base of plasma hypothesis of emission from the coronal plasma. This radio emission is connected with fast electron beams, which propagate in common case in non homogeneous magneto active plasma.

- development of the theory of electron beam propagation in plasma taking into account interaction of these beams with plasma waves, which generate them, and the theory of radio emission of these beams.- development of the theory of radar reflection from plasma turbulence, which was generated by electron beams and shocks.

• The Ukrainian team consists of 4 professors, 3 postdocs, 3 researchers, 2 PhD students and 8 technicians.
• We have experience of longstanding scientific cooperation with the following partners:
• Space Research Institute (Graz, Austria),
• Swedish Institute of Space Physics (Uppsala, Sweden),
• Institute of Applied Physics RAS (Nizhny Novgorod, Russia)
• Astrophysical Institute Potsdam (Potsdam, Germany)
• Department de Radioastronomie CNRS, Observatoire de Paris, (Meudon, France)
• Department of Physics and Astronomy, University of Glasgow (Glasgow, UK)

Role of the team in the project: Our Institute plays the leading role in the observations of the sporadic solar radio emission which is associated with CME at frequencies 10-70 MHz. We define the main characteristics of this radio emission, such as fluxes, frequency drift rates of separate components of the emission (type III and II bursts), their durations (type II, III and IV bursts), their spectral distribution (fundamental and harmonic components of type II and III bursts). We study also the properties of spectral and temporal details of the type II bursts (lanes, clouds, herringbone structure, short sub-bursts), type IV bursts (fiber-bursts, zebra structure). Newly installed at UTR-2 heliograph together with using the telescope as local short-base interferometer provide the possibility of founding the positions of the solar bursts sources on the solar disk and their sizes. Using of these methods in broadband observations will allow considering the dynamics of these sources at heights 1.5-3 solar radii. It also will join existing radio manifestations of the CMEs at meter and hectometer wavelengths and fill the existing gap in the experimental data.

Creating the models of the fast electron beams propagation through coronal plasma in the kinetic approach will explain the properties of powerful type III bursts and fiber-bursts, which are the fine structure of type IV bursts.ORGANIZATION: Institute of Radio Astronomy of National Acad. of Science of Ukraine (Ukraine)

• Abbreviation used in the proposal: NASU/IRA
• Group name: Institute of Radio Astronomy (IRA)
• Department/division: National Academy of Sciences of Ukraine
• Leader of the team: Dr. Valentin Melnik
• Other contact person: Dr. Vladimir Dorovskyy
• Address: Chervonopraporna str, 4, Kharkov, 61002, Ukraine
• e-mail: melnik@ri.kharkov.ua; dorovsky@ri.kharkov.ua
• web-site: http://www.ri.kharkov.ua/