scholarly journals Observation of eruptive events with the Siberian Radioheliograph

2018 ◽  
Vol 4 (3) ◽  
pp. 17-27
Author(s):  
Анастасия Федотова ◽  
Anastasiya Fedotova ◽  
Александр Алтынцев ◽  
Alexander Altyntsev ◽  
Алексей Кочанов ◽  
...  
Keyword(s):  
Radio Emission ◽  
Magnetic Structure ◽  
Microwave Emission ◽  
Radio Brightness ◽  
Microwave Source ◽  
Local Sources ◽  
Cold Matter ◽  
Radio Map

We describe methods for monitoring eruption activity with the first phase of the multiwave Siberian Radioheliograph (SRH-48). We give examples of the recorded eruptive events: 1) rise of a prominence above the limb observed in the radio map sequence of April 24, 2017; 2) a jet recorded on August 2, 2017, whose cold matter screened a compact microwave source for several tens of minutes. The shading due to the jet appearance was observed on SRH-48 correlation curves as the so-called “negative” burst. Using the “negative” burst on the correlation curves of February 9, 2017 as an example, we show that the intervals with depression of the microwave emission of local sources are not always caused by shading of their emission. In this event, the radio brightness decreased within ten hour period of the increased quasi-stationary emission during the development of AR 12635 magnetic structure. Similar behavior was observed in EUV, SXR, and radio emission at 17 GHz.

scholarly journals Observation of eruptive events with the Siberian Radioheliograph

2018 ◽  
Vol 4 (3) ◽  
pp. 13-19 ◽  
Author(s):  
Анастасия Федотова ◽  
Anastasiya Fedotova ◽  
Александр Алтынцев ◽  
Alexander Altyntsev ◽  
Алексей Кочанов ◽  
...  
Keyword(s):  
Radio Emission ◽  
Magnetic Structure ◽  
Microwave Emission ◽  
Radio Brightness ◽  
Microwave Source ◽  
Local Sources ◽  
Cold Matter ◽  
Radio Map

We describe methods for monitoring eruption activity with the first phase of the multiwave Siberian Radioheliograph (SRH-48). We give examples of the recorded eruptive events: 1) rise of a prominence above the limb observed in the radio map sequence of April 24, 2017; 2) a jet recorded on August 2, 2017, whose cold matter screened a compact microwave source for several tens of minutes. The shading due to the jet appearance was observed on SRH-48 correlation curves as the so-called “negative” burst. Using the “negative” burst on the correlation curves of February 9, 2017 as an example, we show that the intervals with depression of the microwave emission of local sources are not always caused by shading of their emission. In this event, the radio brightness decreased within ten hour period of the increased quasi-stationary emission during the development of AR 12635 magnetic structure. Similar behavior was observed in EUV, SXR, and radio emission at 17 GHz.

scholarly journals Coronal Magnetic Fields of Algol Binaries from Microwave Spectra

1991 ◽  
Vol 130 ◽  
pp. 498-500
Author(s):  
G. Umana ◽  
C. Trigilio ◽  
R. M. Hjellming ◽  
S. Catalano ◽  
M. Rodonò
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Mass Exchange ◽  
Thermal Emission ◽  
Magnetic Activity ◽  
Microwave Emission ◽  
X Ray ◽  
Coronal Magnetic Fields ◽  
Hydrodynamic Processes ◽  
Hot Corona

Algol-type binaries are basically known to undergo hydrodynamic processes related to mass exchange between components. Recent observations on radio, X-ray emission and flare-like events have raised the question of possible magnetic activity in the secondary component of these systems (Hall, 1989).From a microwave emission survey we have shown that the radio emission from Algol systems cannot be accounted for by thermal emission from an hot corona (T ≥ 107K) and that their radio luminosities compare very well with those of the magnetically active RS CVn systems (Umana et al., 1990).

scholarly journals Simulating Siberian Radioheliograph response to the quiet Sun

2018 ◽  
Vol 4 (4) ◽  
pp. 106-113
Author(s):  
Сергей Лесовой ◽  
Sergey Lesovoi ◽  
Вероника Кобец ◽  
Veronika Kobets
Keyword(s):  
Flux Density ◽  
Solar Disk ◽  
Beam Pattern ◽  
Microwave Emission ◽  
The Sun ◽  
Extended Source ◽  
Microwave Source ◽  
Quiet Sun ◽  
Correlation Plot ◽  
The Impact

The Siberian Radioheliograph (SRH) correlation plot is the time dependence of the sum of absolute values of complex correlations over all baselines. These plots are built for each operating frequency of SRH. The correlation is related not only to the spatial coherence of the incident microwave emission but also to antenna gains. That is why we have to consider real SRH antenna gains and shadowings. Correlation plots obtained by SRH are related to microwave flux density of the Sun and spatial features of microwave sources. Also the correlation plots show variability of SRH beam pattern in time with constant flux density and spatial structure of sources. The SRH beam pattern depends on position of the Sun with respect to SRH, which changes with time. This leads to variations of these plots, which can be confused, for example, with the quasi-harmonic oscillations of the microwave flux produced by sources located above sunspots. Because the solar disk is an extended source, the correlation plot variability is mostly due to the SRH response to the quiet Sun. The smaller is the microwave source, the smaller are the correlation plot variations caused by a change of the beam pattern. Relatively fast variations result from long baseline responses, so it is undesirable to exclude them from the plots. Moreover, the sensitivity of the plots is better when all baselines are taken in account. The impact of the correlation plot variations on the eruptive event response is especially strong because variations of microwave flux during such events are comparable with those of the correlation plots in magnitude and time. From the above it seems reasonable to simulate the SRH response to the quiet solar disk and correct the correlation plots. In this work, we propose a method for simulating correlation plots, which allows us to correct their variations caused by time and frequency dependence of SRH response to the solar disk. The correlation plots are simulated either by summing all model antenna pair responses to the model solar disk or by summing the corresponding values of the solar disk visibility under the assumption that the visibility is ~J1(x)/x, where J1(x) is the Bessel function of the first kind. Also we consider the shadowing of antennas nearest to the center of the SRH antenna array.

scholarly journals Simulating Siberian Radioheliograph response to the quiet Sun

2018 ◽  
Vol 4 (4) ◽  
pp. 82-87 ◽  
Author(s):  
Сергей Лесовой ◽  
Sergey Lesovoi ◽  
Вероника Кобец ◽  
Veronika Kobets
Keyword(s):  
Flux Density ◽  
Solar Disk ◽  
Beam Pattern ◽  
Microwave Emission ◽  
The Sun ◽  
Extended Source ◽  
Microwave Source ◽  
Quiet Sun ◽  
Correlation Plot ◽  
The Impact

The Siberian Radioheliograph (SRH) correlation plot is the time dependence of the sum of absolute values of complex correlations over all baselines. These plots are built for each operating frequency of SRH. The correlation is related not only to the spatial coherence of the incident microwave emission but also to antenna gains. That is why we have to consider real SRH antenna gains and shadowings. Correlation plots obtained by SRH are related to microwave flux density of the Sun and spatial features of microwave sources. Also the correlation plots show variability of SRH beam pattern in time with constant flux density and spatial structure of sources. The SRH beam pattern depends on position of the Sun with respect to SRH, which changes with time. This leads to variations of these plots, which can be confused, for example, with the quasi-harmonic oscillations of the microwave flux produced by sources located above sunspots. Because the solar disk is an extended source, the correlation plot variability is mostly due to the SRH response to the quiet Sun. The smaller is the microwave source, the smaller are the correlation plot variations caused by a change of the beam pattern. Relatively fast variations result from long baseline responses, so it is undesirable to exclude them from the plots. Moreover, the sensitivity of the plots is better when all baselines are taken in account. The impact of the correlation plot variations on the eruptive event response is especially strong because variations of microwave flux during such events are comparable with those of the correlation plots in magnitude and time. From the above it seems reasonable to simulate the SRH response to the quiet solar disk and correct the correlation plots. In this work, we propose a method for simulating correlation plots, which allows us to correct their variations caused by time and frequency dependence of SRH response to the solar disk. The correlation plots are simulated either by summing all model antenna pair responses to the model solar disk or by summing the corresponding values of the solar disk visibility under the assumption that the visibility is ~J1(x)/x, where J1(x) is the Bessel function of the first kind. Also we consider the shadowing of antennas nearest to the center of the SRH antenna array.

scholarly journals The observation of 10–50 KeV solar flare X-rays by the OGO satellites and their correlation with solar radio and energetic particle emission

1968 ◽  
Vol 35 ◽  
pp. 490-509
Author(s):  
R. L. Arnoldy ◽  
S. R. Kane ◽  
J. R. Winckler
Keyword(s):  
Magnetic Field ◽  
Solar Flare ◽  
Radio Emission ◽  
Total Energy ◽  
Total Duration ◽  
Microwave Emission ◽  
X Rays ◽  
Ionization Chambers ◽  
X Ray ◽  
Peak Intensity

More than 70 cases have been observed of energetic solar flare X-ray bursts by large ionization chambers on the OGO satellites in space. The ionization chambers have an energy range between 10 and 50 KeV for X-rays and are also sensitive to solar protons and electrons. A study has been made of the X-ray microwave relationship, and it is found that the total energy released in the form of X-rays between 10 and 50 KeV is approximately proportional to the peak or total energy simultaneously released in the form of microwave emission. For a given burst the rise time, decay time and total duration are similar for the 10–50 KeV X-rays and the 3 to 10 cm radio emission. Roughly exponential decay phases are observed for both emissions with time constants between 1 and 10 min. All 3 or 10 cm radio bursts with peak intensity greater than 80 solar flux units are accompanied by an X-ray burst greater than 3 × 10−7 ergs cm−2 sec−1 peak intensity. The probability of detecting such X-ray events is low unless the radio spectrum extends into the centimetric range of wavelengths. The best correlation between cm-λ and energetic X-rays is observed for the first event in a flare. Subsequent structure and second bursts may not correspond even when the radio emission is rich in the microwave component. The mechanism for the energetic X-rays is shown to be bremsstrahlung probably of fast electrons on a cooler plasma. If the radio emission is assumed to be synchrotron radiation then a relationship is developed between density and magnetic field which meets the observed quantitative results. One finds, on the average, that 5 × 10−54 joules m−2 (CPS)−1 of microwave energy at the Earth are required per electron at the Sun to provide the radio emission for the various events.A strong correlation between interplanetary solar flare electrons observed by satellite and X-ray bursts is shown to exist. This correlation is weak for solar proton events. One may infer a strong propagation asymmetry for solar flare electrons along the spiral interplanetary magnetic field.

Radio Emission from Starspots on RSCVn Binary HR1099

1986 ◽  
Vol 6 (3) ◽  
pp. 316-319 ◽  
Author(s):  
John D. Bunton ◽  
R. T. Stewart ◽  
O. B. Slee ◽  
G. J. Nelson ◽  
Alan E. Wright ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Light Curve ◽  
Circular Polarization ◽  
Rotation Rate ◽  
Source Model ◽  
Microwave Emission ◽  
Relativistic Electrons ◽  
Synchrotron Source

AbstractProperties of the microwave emission from HR1099 are examined in an attempt to determine whether the emission arises as gyro-synchrotron radiation from mildly relativistic electrons trapped in magnetic fields above starspots on the active K subgiant component. It is shown that radio curves do not exhibit a systematic variation in phase with the rotation rate, as one might expect for emission from a source situated above a long-lived starspot. However, there is some evidence that the radio flaring occurs at two preferred longitude zones. Whether these zones agree with starspot locations remains to be determined by light curve modelling. What we can say with confidence is that the measured spectral index of the microwave emission does not fit a simple gyro-synchrotron source model, such as that proposed to explain the observed reversal with frequency of the sense of circular polarization.

scholarly journals Galactic Radio Emission Below 16·5 MHz and the Galactic Emission Measure

1982 ◽  
Vol 35 (1) ◽  
pp. 91 ◽  
Author(s):  
GRA Ellis
Keyword(s):  
Radio Emission ◽  
Emission Measure ◽  
Kinetic Temperature ◽  
The South ◽  
Radio Brightness ◽  
Galactic Emission ◽  
Galactic Radio Emission ◽  
Galactic Radio ◽  
Galactic Background

New maps of the distribution of the galactic background radio emission are given for wave frequencies of 2�1,3�7,4�7,5�5,8�3,13 and 16�5 MHz. The angular resolutions of the observations were 7.5�, 6.8�, 3 � � 10�, 4.5�, 3.0�, 1.9� and 1.5� respectively. A map of the quantity ?? in galactic coordinates is obtained from an analysis of the changes in the radio brightness distributions with frequency. For an assumed electron kinetic temperature of 104 K, the emission measure is found to vary from 3�9 cm -6 pc near the south galactic pole to 140 cm -6 pc near the equator.

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