Ultrahigh Time Resolution Observations of Radio Bursts on AD Leonis

Osten, Rachel A.; Bastian, T. S.

doi:10.1086/525013

Cited by 66 publications

(58 citation statements)

References 39 publications

(58 reference statements)

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“…For example, it is known that some radio spectra of the flare activity on AD Leonis are similar to what is shown in Fig. 1, and see the paper by Osten & Bastian (2008). This means that the model presented here can also be applicable to these star spectra.…”

Section: Discussionsupporting

confidence: 64%

Radio spectra generated during coalescence processes of plasmoids in a flare current sheet

Karlický

Bárta

Rybák

2010

A&A

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Aims. Motivated by observations of the drifting pulsating structures (DPSs) in solar radio spectra, we study the electromagnetic (radio) emission generated during tearing and coalescence processes in a flare current sheet. Methods. For numerical simulations, we used a 2.5-D particle-in-cell electromagnetic relativistic code. Numerical data were analyzed by the wavelet methods. Results. It is found that the electromagnetic emission is generated during a coalescence of plasmoids, and it has a quasi-periodic character. Detailed analysis reveals that the electromagnetic emission is produced around the interacting plasmoids just before their coalescence into a larger one. The period in variations of electromagnetic emission corresponds to that of magnetic field at the same region. Reflections of the electromagnetic waves between interacting plasmoids are recognized. The computed and observed periodicities are discussed. The similarity of the DPSs with some radio bursts observed during star flares indicates a broader applicability for this model.

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Section: Discussionsupporting

confidence: 64%

Radio spectra generated during coalescence processes of plasmoids in a flare current sheet

Karlický

Bárta

Rybák

2010

A&A

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“…In addition to at the Sun, radio bursts have also been observed for nearby flare stars (Osten & Bastian 2008), where higher densities and magnetic fields are also implied.…”

Section: Introductionmentioning

confidence: 96%

Fundamental and harmonic plasma emission in different plasma environments

Ganse

Kilian

Spanier

et al. 2014

A&A

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Aims. Emission of radio waves from plasmas through plasma emission with fundamental and harmonic frequencies is a familiar process known from solar type II radio bursts. Current models assume the existence of counterstreaming electron beam populations excited at shocks as sources for these emission features, which limits the plasma parameters to reasonable heliospheric shock conditions. However, situations in which counterstreaming electron beams are present can also occur with different plasma parameters, such as higher magnetisation, including but not limited to our Sun. Similar radio emissions might also occur from these situations. Methods. We used particle-in-cell simulations to compare plasma microphysics of radio emission processes from counterstreaming beams in different plasma environments that differed in density and magnetization. Results. Although large differences in wave populations are evident, the emission process of type II bursts appears to be qualitatively unaffected and shows the same behaviour in all environments.

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“…This means that we need an algorithm that can reliably decompose the overlapping substructures into individual objects with distinct shape characteristics. So far, a number of studies have been done to identify and extract well-isolated type IIIYlike bursts in the solar (Aschwanden & Benz 1986) and stellar (Osten & Bastian 2006 cases, as well as in cases of isolated spikes (Dąbrowski et al 2005). Rozhansky et al (2008) has taken this a step further by developing an algorithm for decomposing a dense spike cluster onto individual Gaussian spectral peaks in the frequency domain.…”

Section: Introductionmentioning

confidence: 99%

Spike Decomposition Technique: Modeling and Performance Tests

Nita

Fleishman

Gary

2008

Astrophysical Journal

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We develop an automated technique for fitting the spectral components of solar microwave spike bursts, which are characterized by narrowband spectral features. The algorithm is especially useful for periods when the spikes occur in densely packed clusters, where the algorithm is capable of decomposing overlapping spike structures into individual spectral components. To test the performance and applicability limits of this data reduction tool, we perform comprehensive modeling of spike clusters characterized by various typical bandwidths, spike densities, and amplitude distributions. We find that, for a wide range of favorable combinations of input parameters, the algorithm is able to recover the characteristic features of the modeled distributions within reasonable confidence intervals. Having model-tested the algorithm against spike overlap, broadband spectral background, noise contamination, and possible malfunction of some spectral channels, we apply the technique to a spike cluster recorded by the Chinese Purple Mountain Observatory (PMO) spectrometer, operating above 4.5 GHz. We study the variation of the spike distribution parameters, such as amplitude, bandwidth, and related derived physical parameters, as a function of time. The method can be further applied to observations from other instruments and to other types of fine structures.

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Ultrahigh Time Resolution Observations of Radio Bursts on AD Leonis

Cited by 66 publications

References 39 publications

Radio spectra generated during coalescence processes of plasmoids in a flare current sheet

Radio spectra generated during coalescence processes of plasmoids in a flare current sheet

Fundamental and harmonic plasma emission in different plasma environments

Spike Decomposition Technique: Modeling and Performance Tests

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