V. N. Melnik

Institute of Radio Astronomy NAS | ri.kharkov.ua · Department of Astrophysics

CITATION Shevchuk M, Melnik V, Brazhenko A, Dorovskyy V, Frantsuzenko A, Poedts S and Magdalenic J (2024), Polarization properties of the decameter spikes. An analysis of the observational polarization properties of the decameter spikes is presented in the paper. It is shown that decameter spikes possess high degree of circular polarization with av...

Studies of the quiet Sun radio emission were carried out in a wide range of wavelengths from extremely short up to decameter ones. At the longest wavelengths, the measurements of angular sizes of the solar corona were previously carried out using the UTR-2 radio telescope in the scanning mode. We have developed a simple interferometric technique fo...

We present results of observations of Type IV burst with unusual high polarization equalled in maximum phase about 100%. This burst was registered both by URAN-2 and NDA radio telescopes on 13 July 2022. It continued for about 5 hours and consisted of sub-bursts with high frequency drift rates and had short durations. We associate it with the weak...

We present the results of observations of complex powerful type II burst associated with narrow Earth-directed CME, which was ejected at around 11 UT on 31 May 2013. The observations were performed by radio telescope UTR-2, which operated as local interferometer, providing the possibility of detection of the spatial parameters of the radio emission...

Subject and Purpose. The sporadic radio emissions coming from the Sun in a broad frequency range contain a lot of important information concerning the solar corona, parameters of the radio frequency sources therein, and the parameter variations resulting from active processes on and about the Sun. These have been the reasons for recent launches of...

We discuss properties of Type IV burst observed by radio telescopes URAN-2 (Ukrainian Radio Interferometer of NASU-2) and NDA (Nançay Decameter Array) on 13 July 2022. This burst was registered at frequencies 26–80 MHz and lasted from 07:00 to 12:00 UT. It had the fine structure in the form of sub-bursts similar to decameter Type III-like bursts, w...

Purpose: The overview of the scientifi c papers devoted to the study of the solar decameter radio emission with the world’s largest UTR-2 radio telescope (Ukraine) published for the last 50 years. Design/methodology/approach: The study and analysis of the scientifi c papers on both sporadic and quiet (thermal) radiation of the Sun recorded with th...

Purpose: A historical review of the experimental base development of low-frequency radio astronomy in Ukraine, since its foundation half a century ago by an outstanding scientist S.Ya. Braude to the current state. Design/methodology/approach: The constant progress of electronic, computer and digital technologies, information and telecommunication t...

At present a number of space missions (Parker, Juno, STEREO, SOHO, Wind and others) intensively investigates the Sun, solar wind and solar system planets. Among other, these spacecrafts are equipped with receivers of space radio emission. In case of space craft, there is a possibility to observe space radio emission at frequencies which are less th...

An inverted U burst with equally developed ascending and descending branches observed by the Giant Ukrainian Radio Telescope (GURT) on 18 April 2017 in meter wavelengths band is discussed. This U burst was attributed to the high coronal loop in active region NOAA 12651 above the limb. Under the assumption that, associated with the burst, a coronal...

Properties of type III and type IIIb bursts in the frequency band of 8 – 80 MHz observed by the radio telescopes Ukrainian Radio Interferometer of NASU-2 (URAN-2) (Poltava) and Giant Ukrainian Radio Telescope (GURT) (Kharkiv) during the Parker Solar Probe (PSP) perihelion in April 2019 are discussed. These correspond to those that were observed by...

An inverted U burst with equally developed ascending and descending branches observed by Giant Ukrainian Radio Telescope (GURT) on 18 April 2017 in meter wavelengths band is discussed. This U burst was attributed to the high coronal loop above the limb active region NOAA 12651. Under the assumption that, associated with the burst, the coronal loop...

Properties of type III and type IIIb bursts in the frequency band of 8-80 MHz observed by the radio telescopes Ukrainian Radio Interferometer of NASU-2 (URAN-2) (Poltava) and Giant Ukrainian Radio Telescope (GURT) (Kharkiv) during the Parker Solar Probe (PSP) perihelion in April 2019 are discussed. These correspond of those that were observed by PS...

We discuss properties of a Type IV burst, which was observed on 2017 September 6, as a result of the powerful flare X 9.3. At decameter wavelengths this burst was observed by the radio telescopes STEREO A, URAN-2, and NDA at frequencies 5-35 MHz. This moving Type IV burst was associated with a coronal mass ejection (CME) propagating in the southwes...

We discuss properties of a Type IV burst, which was observed on 2017 September 6, as a result of the powerful flare X 9.3. At decameter wavelengths this burst was observed by the radio telescopes STEREO A, URAN-2, and NDA at frequencies 5 - 35 MHz. This moving Type IV burst was associated with a coronal mass ejection (CME) propagating in the southw...

Cutting edge astrophysical studies require more and more observing time at low-frequency radio telescopes, which is limited and quite expensive. Modern digital signal processing systems still unable to provide affordable computational and storage resources to allow simultaneous beamforming in a wide frequency range for multiple studies. Low-frequen...

Shock waves in the solar corona are closely associated with coronal mass ejections and flares. The longest-known and frequently studied signatures of coronal shock waves are metric type II radio bursts, which provide information on the shock driver and ambient plasma conditions. We report on outstanding high frequency/time resolution LOw Frequency...

A new class of one-dimensional solar wind models is developed within the general polytropic, single-fluid hydrodynamic framework. The particular case of quasi-adiabatic radial expansion with a localized heating source is considered. We consider analytical solutions with continuous Mach number over the entire radial domain while allowing for jumps i...

A new class of one-dimensional solar wind models is developed within the general polytropic, single-fluid hydrodynamic framework. The particular case of quasi-adiabatic radial expansion with a localized heating source is considered. We consider analytical solutions with continuous Mach number over the entire radial domain while allowing for jumps i...

A new class of one-dimensional solar wind models is developed within the general poly-tropic, single-fluid hydrodynamic framework. The particular case of quasi-adiabatic radial expansion with a localized heating source is considered. We consider analytical solutions with continuous Mach number over the entire radial domain while allowing for jumps...

Abstract The decay of a Type III burst into two Type III bursts was registered during solar observations by GURT and URAN-2 radio telescopes on 2017 April 18. This was the first time such a phenomenon was observed. Newborn Type III bursts have drift rates smaller than that of a decaying Type III burst. Such decays of Type III bursts were predicted...

In the present paper an analysis of the polarization properties of the solar decameter spikes is performed. We found that decameter spikes can possess both left and right circular polarization which changes from 0 up to 100% with an average value 50%.

A decay of Type III burst into two Type III bursts was registered during solar observations by GURT and URAN-2 radio telescopes on April 18, 2017. Such phenomenon was observed for the first time. Newborn Type III bursts have drift rates smaller than that of decaying Type III burst. Such decays of Type III bursts were predicted by a gas-dynamic theo...

Type III bursts are intense, non thermal sporadic solar radio emissions that can be characterized by their rapid development in time and frequency. High sensitive radio telescopes like the UTR-2 (Ukrainian T-shaped radio telescope, v.2) operate in strong RFI (radio-frequency interference) polluted frequency domains and generate large amount of unca...

In the paper we present the preliminary results of analysis of the solar Type IIIb bursts properties. Namely the parameters of their fine structure known as striae are studied in the continuous frequency band 8-32 MHz. It is shown that durations and instantaneous frequency bandwidths depend on the observing frequency. Notably, bandwidth increases a...

Context . As is well known, coronal mass ejection (CME) propagation often results in the fragmentation of the solar atmosphere on smaller regions of density (magnetic field) enhancement (depletion). It is expected that this type of fragmentation may have radio signatures. Aims . The general aim of the present paper is to perform a comparative analy...

We studied a radio emission of the quiet Sun at decameter wavelengths to determine its angular dimensions. Observations were conducted using interferometers composed of antenna sections of the UTR-2 radio telescope. A number of interferometers with baselines of 225 to 1400 m, oriented along the meridian, operated at two frequencies of 20 and 25 MHz...

Using the Low Frequency Array (LOFAR), we analyse the source sizes and locations of the fine frequency structuresin a solar radio burst. The high time resolution allows us to determine the location and the size of the radioemission source, and its evolution with time, following the radio emission propagation through the solar corona.It is found tha...

Results of solar observations at 20 and 25 MHz by the UTR-2 (\textit{Ukrainian T-shaped Radio telescope of the second modification}) radio telescope in the interferometric session from 27 May to 2 June 2014 are presented. In such a case the different baselines 225, 450, and 675 m between sections of East--West and North--South arms of the radio tel...

Using the Low Frequency Array (LOFAR), we analyse the source sizes and locations of the fine frequency structures in a solar radio burst. The high time resolution allows us to determine the location and the size of the radio emission source, and its evolution with time, following the radio emission propagation through the solar corona. It is found...

We report on the results of observations of a type IV burst by URAN-2 (Ukrainian Radio interferometer of Academy Scienses) in the frequency range 22 - 33 MHz, which is associated with the CME (coronal mass ejection) initiated by a behind-the-limb active region (N05E151). This burst was observed also by the radio telescope NDA (Nancay Decameter Arra...

A large number of Type IIIb–III pairs, in which the first component is a Type IIIb burst and the second one is a Type III burst, are often recorded during decameter Type III burst storms. From the beginning of their observation, the question of whether the components of these pairs are the first and the second harmonics of radio emission or not has...

The original version of this article contained errors in Refs 15, 27, 32, 33 and 43, which were incorrectly given with the wrong journal name "Solid Phys." rather than the correct "Sol. Phys.". This has now been corrected in the PDF and HTML versions of the article.

We present the results of observations of a complex and powerful type II radio burst associated with a narrow Earth-directed coronal mass ejection (CME), which was ejected at around 11 UT on 31 May 2013. The observations were performed by the radio telescope UTR-2, which operated as a local interferometer, providing the possibility of detection of...

Results of solar radio emission observations by radio telescopes UTR-2 and URAN-2 in May-June 2014 are discussed. Observations by the radio telescope UTR-2 were carried out in the interferometer mode using West-East arm of the UTR-2 on 29 May and North-South arm on 2 June at frequencies 20 and 25 MHz. On 29 May some powerful simple type III bursts...

On April 7, 2011 a CME was observed originating above the AR NOAA 1176, located behind the solar limb. This CME was associated with type IV burst, type II bursts and groups of J-bursts and type III bursts. Groups of J-bursts and type III bursts were observed from 10:50 to 11:20 UT. There was a group of J-bursts from 10:52 to 10:57 UT, originating f...

Researching of the third harmonic radiation is important for progress in theoretical aspects of investigation of solar corona. Analysis of the third harmonic of solar type III radio bursts at decameter wavelengths can be useful for giving more precise definition to the plasma emission mechanism and for accuracy of solar plasma parameters on relevan...

Unusual solar bursts were observed simultaneously by two decameter radio telescopes UTR-2 (Kharkov, Ukraine) and URAN-2 (Poltava, Ukraine) on 3 June 2011 and 18 August 2012 in the frequency range 8-33 MHz with time and frequency resolution 100 ms and 4 kHz correspondingly. The observed radio bursts have some unusual properties, which are not typica...

On 9 July 2013 from 5:30 UT till 13:28 UT more than 1000 S-bursts were recorded by the Ukrainian radio telescope UTR-2 operated in the frequency band 9-32 MHz. All S-bursts were low intensity events with an average flux of about 10 s.f.u. and a minimum flux as low as 0.2 s.f.u. which made their detection with small instruments practically impossibl...

Recently solar Type III bursts with fine time structure have been observed by radio telescope UTR-2 at frequencies 10 - 30 MHz. For the first time Type III-like bursts with high frequency drift rates were observed at these frequencies too. All this became possible due to both high sensitivity and high time resolution of UTR-2. The properties of dec...

ABSTRACT Context. The Sun’s activity can appear in terms of radio bursts. In the frequency range 8􀀀33 MHz the radio telescope URAN-2 observed special fine structures appearing as a chain of stripes of enhanced radio emission in the dynamic radio spectrum. The chain drifts slowly from 26 to 23 MHz within 4 min. The individual structures consist of a...

Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio wave propagation has long been a major challenge in solar physics. Here w...

We report the systematic analysis of zebra-like fine spectral structures in decametric frequency range of Jovian radio emission. Observations were performed by the large ground-based radio telescope Uran-2 during three observation campaigns between, Sep., 2012, and May, 2015. In total, 51 zebra pattern (ZP) events were detected. These rare fine rad...

Results of observations of type IV burst (November 7, 2013) by the radio telescope URAN-2 (Poltava, Ukraine) in the frequency range 22-32 MHz, which accompanied by CME associated with a behind-limb active region with longitude -150 degree, are presented. This burst was registered also by STEREO A and B in the frequency range 8-14 MHz and by NDA (Na...

On March 16, 2016, a type III burst was observed with the ground-based radio telescopes LOFAR and URAN-2 as well as with the radiospectrometer aboard the spacecraft WIND.It started at 80 MHz at 06:37 UT and reached 50 kHz after 23 minutes. A type III burst are considered as the radio signature of an electron beam travelling from the corona into the...

Recent SECCHI COR2 observations on board STEREO-A spacecraft have detected density structures at a distance of 2.5--15~R propagating with periodicity of about 90~minutes. The observations show that the density structures probably formed in the lower corona. We used the large Ukrainian radio telescope URAN-2 to observe type IV radio bursts in the fr...

This paper describes digital radio astronomical receivers used for decameter and meter wavelength observations. This paper describes digital radio astronomical receivers used for decameter and meter wavelength observations. Since 1998, digital receivers performing on-the-fly dynamic spectrum calculations or waveform data recording without data loss...

We report the first observation of zebra-like fine spectral structures in decametric frequency range of Jovian radio emission. This zebra patterns are observed in frequency range from 12 to 30 MHz as a number of quasi-equidistant stripes (from 3 to 9) of enhanced brightness with fast parallel drift in time. The features have been observed by ground...

Rapid progress currently takes place in the field of low-frequency radio astronomy of meterdecameter-hectometer range of wavelengths. It is caused by a radical modernization of the existing radio telescopes, creation of a new generation of instruments, space-borne observations, and by the development of research of all classes of astrophysical obje...

The current status of the large decameter radio telescope UTR-2 (Ukrainian T-shaped Radio telescope) together with its VLBI system called URAN is described in detail. By modernization of these instruments through implementation of novel versatile analog and digital devices as well as new observation techniques, the observational capabilities of UTR...

Purpose: define and theoretically substantiate the range of astrophysical problems that may be efficiently solved using small antenna arrays. Design/methodology/approach: Observation parameters and configurations of a set of small antenna arrays included in the future Giant Ukrainian radio telescope, have been derived based on the theoretical anal...

Results of solar radio emission observations by the radio telescopes UTR-2 (Kharkiv, Ukraine) and URAN-2 (Poltava, Ukraine) on 29 May 2014 are discussed. Observations by the radio telescope UTR-2 were carried out in the interferometer regime using West-East arm of the UTR-2 with bases 225m, 450m and 675m at frequencies 20 MHz and 25 MHz. This day s...

We investigate the dynamic spectra of the Sun and Jovian decametric radiation obtained by the authors with the radio telescopes UTR-2 and URAN-2 (Kharkov, Poltava, Ukraine). We focus on the similar structures that appear on the dynamic spectra of those objects: S-bursts, drifting pairs, absorption bursts and zebra patterns. Similarity in structures...

An event on 14 June 2012, observed with the radio telescopes UTR-2 (Kharkov, Ukraine), URAN-2 (Poltava, Ukraine), and NDA (Nançay, France) during a joint Summer campaign, is analyzed and discussed. The high solar activity resulted in a storm of spikes, and a storm of Type III bursts, Type IIIb bursts, and a Type IV burst observed in the decameter b...

The characteristics of the type II bursts with herringbone structure observed both by ground based radio telescopes (UTR-2, URAN-2) and spaceborn spectrometers (STEREO A-B) are discussed. The burst was recorded on 7 June, 2011 in the frequency band 3--33~MHz. It was characterized by extremely rich fine structure. The statistical analysis of more th...

We study a unique fine structure in the dynamic spectrum of the solar radio emission discovered by the UTR-2 radio telescope (Kharkiv, Ukraine) in the frequency band of 20 – 30 MHz. The structure was observed against the background of a broadband type IV radio burst and consisted of parallel drifting narrow bands of enhanced emission and absorption...

The properties of IIIb–III pairs observed by the URAN-2 radio telescope at frequencies 16-32 MHz are analyzed. Observations of these bursts were hold in April, June and September 2011. Durations, frequency drift rates, simultaneous frequency ratio of pairs components and their polarizations are analyzed. Pro and contra of IIIb–III harmonic connecti...

Solar radio observations at 10–30 MHz have been carried out recently using radio telescopes UTR-2 (world's largest radio telescope at decametric wavelengths near Kharkov, Ukraine) and URAN-2 (Poltava, Ukraine). High sensitivity and time resolution of these observations allowed revealing many new interesting features of the coronal radio emission (V...

The low frequency radio astronomy (decameter-meter range, frequencies of 10–300 MHz) currently demonstrates rapid progress all over the world. New generations of large antennas - LOFAR, LWA, MWA and others - have been created in many countries. At the same time Ukrainian radio astronomical systems UTR-2 and URAN still remain the largest and most in...

Solar bursts with high frequency cut off were observed by the URAN-2 radio telescope (Poltava, Ukraine) on 18 August, 2012 in the frequency range 8-32 MHz. Durations of these bursts changed from 30 to 70 s. It is much longer than that for standard type III bursts. Drift rates are much smaller than those of type III bursts are, though much larger th...

The results of the first observations of solar sporadic radio emission within 10 – 70 MHz by the Giant Ukrainian Radio Telescope (GURT) are presented and discussed. Observations in such a wide range of frequencies considerably facilitate the registration of harmonic pairs. The solar U-burst harmonic pair observed on 8 August 2012 is analyzed. The b...

Features of sporadic decameter solar radio emission associated with some active regions according to observations made with radio telescope UTR-2 on August 1, 2014 are considered. Analysis of characteristics of type IV bursts, fiber-bursts and type III bursts, which were preceded and followed by type IV bursts, was carried out. Similarity of origin...

We discuss properties of type III bursts that change the sign of their drift rate from negative to positive and vice versa. Moreover, these bursts may change the sign of their drift rates more than once. These particular type III bursts were observed simultaneously by the radio telescopes UTR-2 (Ukrainian T-shaped Radio telescope, Kharkov, Ukraine)...

U kraine has a substantial experimental base of radio remote sensing for re-search of VarSITI problems. First of all the base includes the largest in the world dec-ameter radio telescope UTR-2 and the URAN system of radio telescopes (Figure 1). --Figure 1. URAN decameter radio telescopes system on Ukraine map: Radio telescopes UTR-2 URAN-1, URAN-2,...

We analyze and discuss the properties of decameter spikes observed in July – August 2002 by the UTR-2 radio telescope. These bursts have a short duration (about one second) and occur in a narrow frequency bandwidth (50 – 70 kHz). They are chaotically located in the dynamic spectrum. Decameter spikes are weak bursts: their fluxes do not exceed 200 –...

We report about observations of decameter type III bursts whose frequency drift rates vary their signs from negative to positive. Moreover drift rates of some bursts vary the sign some times. Positive drift rates for some bursts are changed from 0.44 MHz/s to 12 MHz/s. At the same time the negative drift rates of these bursts are standard values fo...

At present, the physical nature of the basic components of the solar sporadic radiation has been well studied and reliably identified non-equilibrium particle emission mechanisms responsible for their origin [1, 2, and references therein]. Jupiter decameter emission (DAM) represents an extraordinary astrophysical phenomenon which is characterized b...

The positive possibilities of astrophysical objects studies(including the Solar system investigations) using coordinated observations with the largest existing and coming low frequency radio telescopes are shown. The observations of the Sun, Jupiter, Saturn, ant others with UTR-2, URAN, NDA radio telescopes, and WIND, Cassini and STEREO space missi...

We consider the approach to simultaneous (synchronous) solar observations of radio emission by using the STEREO-WAVES instruments (frequency range 0.125–16 MHz) and the largest ground-based low-frequency radio telescope. We illustrate it by the UTR-2 radio telescope implementation (10–30 MHz). The antenna system of the radio telescope is a T-shape-...

Oscillations of decameter type IV bursts were registered at observations of solar radio emission by UTR-2, URAN-2 an NDA during 2011-2012. Large majority of these bursts were accompanied by coronal mass ejections (CMEs), which were observed by SOHO and STEREO in the optical range. Only in some cases decameter type IV bursts were not associated with...

We report decameter type III bursts with changing sign of frequency drift rates, which were observed simultaneously by radio telescopes UTR-2 (Kharkov, Ukraine), URAN-2 (Poltava, Ukraine) and NDA (Nancy, France). These bursts drift from high frequency to low frequency all the time unlike well-known inverted U-bursts, which change the sign of drift...

An unusual solar burst was observed simultaneously by two decameter radio telescopes UTR-2 (Kharkov, Ukraine) and URAN-2 (Poltava, Ukraine) on 3 June 2011 in the frequency range of 16 – 28 MHz. The observed radio burst had some unusual properties, which are not typical for the other types of solar radio bursts. Its frequency drift rate was positive...

Observed oscillations of coronal loops in EUV lines have been successfully used to estimate plasma parameters in the inner corona (< 0.2 R_0, where R_0 is the solar radius). However, coronal seismology in EUV lines fails for higher altitudes because of rapid decrease in line intensity. We aim to use radio observations to estimate the plasma paramet...

The results of the first observations of solar sporadic radio emission within 10 − 70 MHz with the Giant Ukrainian Radio Telescope (GURT), now under construction, are presented. Observations in such a wide range of frequencies allowed considerable increase of the probability of harmonic pairs recording, where a harmonic pair means the pair of burst...

Oscillations of decameter type IV bursts were registered during observations of solar radio emission by UTR-2, URAN-2 and NDA in 2011-2012. Large majority of these bursts were accompanied by coronal mass ejections (CMEs), which were observed by SOHO and STEREO in the visible light. Only in some cases decameter type IV bursts were not associated wit...

There are many physical processes and propagation effects for the producing the time variable radio emission just at the low frequencies (at the decameter wavelength). The study of this radio emission is the important part of the modern radio astronomy. Strong progress in the development of the radio telescopes, methods and instrumentation allowed...

Oscillations of decameter type IV bursts were registered during observations of solar radio emission by UTR-2, URAN-2 and NDA in 2011-2012. Large majority of these bursts were accompanied by coronal mass ejections (CMEs), which were observed by SOHO and STEREO in the visible light. Only in some cases decameter type IV bursts were not associated wit...

Characteristics of the type II burst with "herringbone" structure observed on 7 June 2011 within 3-33 MHz are considered. The burst was recorded both by the two ground-based radiotelescopes (UTR-2, URAN-2) and the spaceborne STEREO radio receivers. For the first time, a detailed statistical analysis of main parameters of the herringbone sub- bursts...

Unusual solar bursts were observed simultaneously by two decameter radio telescopes UTR-2 (Kharkov, Ukraine) and URAN-2 (Poltava, Ukraine) in the frequency range 8-33 MHz on 3 June 2011 and 18 August 2012 [1]. The observed radio bursts have some unusual properties, which are not typical for the other types of solar radio bursts. The main feature of...

Observations of the two M-dwarf flare stars (AD Leonis and EV Lacertae), which were carried out with the radio telescope UTR-2 (Kharkiv, Ukraine) in the range of 16.5-33 MHz, are presented. 167 events of radio emission from AD Leo and 73 events from EV Lac were detected in the period of 2010-2011. These events were considered as stellar emission in...