Engineering Papers⌕ Search

Engineering topics

Pick, M.

Publications and source records attributed to Pick, M..

33 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

The association of radio noise storm enhancements with the appearance of additional material in the corona

Visible light observations of the corona have been combined with radioheliograph observations at metric wavelengths to examine the dynamic behavior of the corona during and after noise storm onsets and enhancements. For the period studied, the occurrence of such radio events is systematically associated with the addition of coronal material in the vicinity of the radio source. Some of the events correspond to mass ejection transients, but they more frequently represent merely a brightening, which grows in 1 hour or less with the coronal region and remains dense and stable for several hours.

Kerdraon, A.↗
NASA NTRS1982

Unusual coronal activity following the flare of 6 November 1980

The major two-ribbon flare that occurred on November 6, 1980 is discussed, using data from the hard X-ray imaging spectrometer aboard the SMM satellite. The post-flare X-ray arch and loops are analyzed, showing the flare characteristics, the coronal arch, the time variations of X-rays after the flare, and the time variation of the maximum intensity at the top of the coronal arch in the 3.5-5.5 keV range. A comparison is made with an earlier arch. The post-flare conronal brightness variations are discussed, including a correlation with a 169 MHz noise stomr, the absence of chromospheric excitation, the brightness and temperature of the X-ray arch, the locations of the brightenings, and the details of the first and fifth brightenings. Problems posed by the observations are discussed.

Svestka, Z.↗
NASA NTRS1982

An association between coronal structures and type III burst sources

Observations of the coronal structures overlying type III radio burst producing regions, obtained with the HAO Coronograph/Polarimeter on board the Solar Maximum Mission, have been combined with observations of the type III bursts from the Mark III Nancay Radioheliograph at 169 MHz. A first qualitative comparison of the data, performed for two periods, indicates that the corona overlying type III producing sites is composed of small, discrete, over-dense structures, which are sometimes diverging and short-lived. The type III burst sources are complex, exhibiting elementary components. It is suggested that the type III burst structure follows that of the corona and that discrete structures may play a fundamental role for type III production.

Trottet, G.↗
NASA NTRS1980

Correlated observations of a spatially resolved type III solar radio burst group and the associated hard X-ray emission

The first measurements of the spatial structure of a group of type III solar radio bursts associated with an impulsive hard X-ray burst are presented. At 169 MHz the radio source has been found to consist of two principal regions separated by about 300,000 km. The two regions together produced a total of four component bursts in good time correlation with spikes in the hard X-ray emission. The observations indicate that electron acceleration/injection occurs over a region which covers a wide range of magnetic field lines.

Kane, S. R.↗
NASA NTRS1976

Non-thermal processes during the 'build-up' phase of solar flares and in absence of flares

Hard X-ray and radio observations indicate production of non-thermal electrons as a common phenomenon of the active sun. A preliminary analysis of three hard X-ray bursts observed with the OGO-5 satellite and radio observations indicate that non-thermal particles are present in the flare region prior to the impulsive (flash) phase and also during the gradual rise and fall (GRF) bursts which are usually explained in terms of purely 'thermal' radiation. The principal difference between the non-thermal electrons observed before the flash phase and during the flash phase appears to be in their total number rather than in the hardness of their energy spectrum. Basic characteristics of the two acceleration processes are probably similar although the total energy converted into non-thermal electrons is considerably larger in the flash phase. Transient absorbing H-alpha features and filament activations are discussed in terms of their ability to produce energetic particle events and magnetic energy release.

Kane, S. R.↗
NASA NTRS1973

A high resolution study in time, position, intensity, and frequency of a radio event on 14 January 1971

High resolution position and spectrum measurements were made of a complex solar radio activity on January 14, 1971, from 1120 to 1130 UT. Positions were measured with 169 MHz Nancay E-W Radioheliograph, while dynamic spectra and polarization were observed with the 60-channel radiospectrograph of Nera. The radio event consisted of two closely similar groups of type 3 bursts and type 2-like details, and a stationary type 4 continuum, including some very clear pulsating structures. The general aspect of this activity is presented.

Caroubalos, C.↗
NASA NTRS1973

The chromospheric association of the metric type 3 bursts - implications concerning the acceleration of solar electrons and the active streamers

In two recent papers it was shown that the metric type 3 emission is closely related to a transient perturbation seen in absorption in the H alpha line. In addition, this perturbation sometimes triggers a flare, sometimes not. This can explain why the type 3 have a poor H alpha flare correlation rate and still are a typical flash phase emission when flare-associated. The characteristics are summarized of the new association proposed. It is assumed that 10 to 100 keV electrons are accelerated in connection with a particular kind of transient H alpha absorbing feature. For as yet undetermined reasons, this process would often, but not always, result in a more efficient acceleration coincident with the early phase of the optical flare. The possibilities that this process could lead occasionally to long lasting subrelativistic particle emissive region are explored.

Axisa, F.↗
NASA NTRS1972

Helmet and active streamers from radio observations

Large coronal regions disconnected from any calcium plages and identified by their thermal emission at 169 mHz play a basic role in the sector structure of the interplanetary medium. It was concluded that these coronal regions are to be interpreted as streamers.

Avignon, Y.↗