Solar flares registered by the IRIS spectrometer onboard the CORONAS-F satellite: Peculiarities of the X-ray emission

Dmitriev, P. B.; Kudryavtsev, I. V.; Lazutkov, V. P.; Matveev, G. A.; Savchenko, M. I.; Skorodumov, D. V.; Charikov, Yu. E.

doi:10.1134/s0038094606020080

Cited by 27 publications

(15 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For beam velocities of 10 10 cm s −1 and acceleration scales of 10 9 cm we find that acceleration characteristic times over 0.1 s will start to become important and lengthen the instability distance with respect to an instantaneous injection. However, we observe 0.1 s time structures in both X-ray (Kiplinger et al 1983;Dennis 1985;Vilmer et al 1994;Dmitriev et al 2006) and radio (e.g. Correia & Kaufmann 1987;Aschwanden et al 1995b;Kaufmann et al 2009) observations.…”

Section: Time Injectionmentioning

confidence: 86%

The low-high-low trend of type III radio burst starting frequencies and solar flare hard X-rays

Reid

Vilmer

Kontar

2014

A&A

View full text Add to dashboard Cite

Aims. Using simultaneous X-ray and radio observations from solar flares, we investigate the link between the type III radio burst starting frequency and hard X-ray spectral index. For a proportion of events the relation derived between the starting height (frequency) of type III radio bursts and the electron beam velocity spectral index (deduced from X-rays) is used to infer the spatial properties (height and size) of the electron beam acceleration region. Both quantities can be related to the distance travelled before an electron beam becomes unstable to Langmuir waves. Methods. To obtain a list of suitable events we considered the RHESSI catalogue of X-ray flares and the Phoenix 2 catalogue of type III radio bursts. From the 200 events that showed both type III and X-ray signatures, we selected 30 events which had simultaneous emission in both wavelengths, good signal to noise in the X-ray domain and >20 s duration. Results. We find that >50% of the selected events show a good correlation between the starting frequencies of the groups of type III bursts and the hard X-ray spectral indices. A low-high-low trend for the starting frequency of type III bursts is frequently observed. Assuming a background electron density model and the thick target approximation for X-ray observations, this leads to a correlation between starting heights of the type III emission and the beam electron spectral index. Using this correlation we infer the altitude and vertical extents of the flare acceleration regions. We find heights from 183 Mm down to 25 Mm while the sizes range from 13 Mm to 2 Mm. These values agree with previous work that places an extended flare acceleration region high in the corona. We also analyse the assumptions that are required to obtain our estimates and explore possible extensions to our assumed model. We discuss these results with respect to the acceleration heights and sizes derived from X-ray observations alone.

show abstract

Section: Time Injectionmentioning

confidence: 86%

The low-high-low trend of type III radio burst starting frequencies and solar flare hard X-rays

Reid

Vilmer

Kontar

2014

A&A

View full text Add to dashboard Cite

show abstract

“…Fig. 7 presents the periodogram obtained by the method of Dmitriev et al (2006). As can be seen from the graph, in addition to the periodicities mentioned above, the spectrum includes a periodicity of about 30 years (Brückner cycle) and also a pronounced quasi-two hundred year periodicity.…”

Section: Climatic Variations Around 68-70 Million Years Agomentioning

confidence: 95%

“…5a was subjected to wavelet analysis (Morlet basis) (Fig.5b), analysis of hidden periodicities by the method developed by Dmitriev et al (2006) (Fig. 7), and also filtering in the ranges of periods 8-10 years, 18-22 years, and 28-32 years (Fig.…”

Section: Climatic Variations Around 68-70 Million Years Agomentioning

confidence: 99%

See 1 more Smart Citation

Variations in climate parameters at time intervals from hundreds to tens of millions of years in the past and its relation to solar activity

Raspopov¹,

Dergachev

Ogurtsov

et al. 2011

Journal of Atmospheric and Solar-Terrestrial Physics

View full text Add to dashboard Cite

“…There is an extensive literature on methods of detection of QPPs and identification of oscillatory components of solar emissions (see O'Shea et al, 2001;McAteer et al, 2004;Dmitriev et al, 2006;Reznikova et al, 2007, and references therein). In the current study we use several of them.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Types of Microwave Quasi-Periodic Pulsations in Single Flaring Loops

et al. 2010

View full text Add to dashboard Cite

Quasi-periodic pulsations (QPP) of microwave emission generated in single flaring loops observed with the Nobeyama Radioheliograph (NoRH) and Nobeyama Radio Polarimeters (NoRP) are studied. Specific features of the time profiles, i.e. the visible presence or absence of QPPs, are not accounted for in the selection. The time evolution of the periods of the QPPs is examined using wavelet and correlation analyses. In ten out of twelve considered events, at least one or more significant spectral components with periods from 5 -60 s have been found. The quality of the oscillations is rather low: Q = πN, where N is the number of cycles, mostly varies in the range 12 to 40, with an average of 25. We suggest that the detected QPPs can be classified into four types: i) those with stable mean periods (e.g. of 15 -20 s or 8 -9 s, the prevailing type); ii) those with spectral drift to shorter periods (mostly in the rise phase of the microwave emission); iii) those with drift to longer periods (mostly in the decay phase); iv) those with multiple periods showing an X-shaped drift (e.g. in the range from 20 -40 s in the rise phase).

show abstract

Solar flares registered by the IRIS spectrometer onboard the CORONAS-F satellite: Peculiarities of the X-ray emission

Cited by 27 publications

References 12 publications

The low-high-low trend of type III radio burst starting frequencies and solar flare hard X-rays

The low-high-low trend of type III radio burst starting frequencies and solar flare hard X-rays

Variations in climate parameters at time intervals from hundreds to tens of millions of years in the past and its relation to solar activity

Types of Microwave Quasi-Periodic Pulsations in Single Flaring Loops

Contact Info

Product

Resources

About