Yu. V. Gotselyuk

CORONAS-F satellite: Tasks for study of particle acceleration

Abstract A low altitude satellite with polar orbit, namely CORONAS-F has been launched on July 31, 2001. We briefly list the possibilities of a complex instrument SKL, and on the basis of similar measurements by CORONAS-I we illustrate the possible tasks for magnetospheric studies. Such orbit allows to sample with relatively high time resolution the projection series of various magnetospheric regions to low altitudes and to indicate changes within.

The solar energetic particle event of April 14, 1994, as a probe of shock formation and particle acceleration

Gradual solar energetic particle (SEP) events observed at 1 AU are associated with coronal mass ejections (CME) that drive shocks which are presumed to accelerate the ions and electrons to suprathermal energies. However, high-energy (> 30 MeV) proton and (> 1 MeV) electron events are nearly always associated with both CMEs and flares, suggesting that the acceleration of those particles, particularly the electrons, could be attributed to the associated flares. Only one clear example of a high-energy SEP event without an active region flare association has been reported previously. We discuss a second such SEP event, on April 14, 1994, associated with a well-observed solar X ray arcade structure spanning ∼ 150° of solar longitude. The SEP event, observed by detectors on the IMP 8 and Koronas I spacecraft, began ∼ 10 hrs after the beginning of the X ray event and was temporally and spatially associated with the last of three weak interplanetary type III radio bursts observed by the Ulysses low-frequency radio experiment. The delayed onset and rapid rise of the SEP intensities preclude a recent interpretation in which SEPs were presumed to be accelerated by a shock driven by a CME which erupted at the onset of the X ray event. Yohkoh soft X ray subtracted images show a large-scale arcade brightening west of ∼ E10° beginning about 8 hours after the initial brightening near the east limb. We suggest that the April 14 SEP event at Earth was produced by a shock driven by a CME associated with the later brightening near central meridian. The initial X ray brightening may also have been associated with an earlier CME.

Dynamics of solar protons in the Earth’s magnetosphere during magnetic storms in November 2004–January 2005

The processes of penetration, trapping, and acceleration of solar protons in the Earth’s magneto-sphere during magnetic storms in November 2004 and January 2005 are studied based on the energetic particle measurements on the CORONAS-F and SERVIS-1 satellites. Acceleration of protons by 1–2 orders of magnitude was observed after trapping of solar protons with an energy of 1–15 MeV during the recovery phase of the magnetic storm of November 7–8, 2004. This acceleration was accompanied by an earthward shift of the particle flux maximum for several days, during which the series of magnetic storms continued. The process of relativistic electron acceleration proceeded simultaneously and according to a similar scenario including acceleration of protons. At the end of this period, the intensification was terminated by the process of precipitation, and a new proton belt split with the formation of two maximums at L ∼ 2 and 3. In the January 2005 series of moderate storms, solar protons were trapped at L = 3.7 during the storm of January 17–18. However, during the magnetic storm of January 21, these particles fell in the zone of quasi-trapping, or precipitated into the atmosphere, or died in the magnetosheath. At the same time, the belts that were formed in November at L ∼ 2 and 3 remained unchanged. Transformations of the proton (and electron) belts during strong magnetic storms change the intensity and structure of belts for a long time. Thus, the consequences of changes during the July 2004 storm did not disappear until November disturbances.

DEPENDENCE OF POLAR CAP SIZE ON INTERPLANETARY PARAMETERS ACCORDING TO "CORONAS-I" DATA

Abstract The polar cap region was reconstructed for all magnetic local time on the basis of ‘CORONAS-I’ data obtained in March–April 1994. Sporadic fluxes of relativistic electrons at high latitudes are studied. According to measurements of electrons with E∼0.5−1.3 MeV we can make conclusion about regions of closed geomagnetic field lines. Polar cap boundary locations and probability of electron flux appearances were determined for different Kp indices and were also the result compared with interplanetary parameters such as solar wind pressure and Bz component of interplanetary magnetic field. Ionospheric projections of last closed geomagnetic field lines were computed using the Tsyganenko-87W magnetosphere model. The relationship of the experimental polar cap boundaries to the model is discussed.

Formation of proton fluxes under the radiation belts during geomagnetic disturbances

The fluxes of energetic particles under the radiation belts are studied using data obtained in the experiments onboard the CORONAS-I and CORONAS-F satelites. The spatial structure of the distributions of proton fluxes with Ep > 1 MeV both near the geomagnetic equator on L ≤ 1.2 and at high latitudes on L ∼ 3.5–6.5 as well as the particle flux variations with geomagnetic activity are analyzed. The scattering processes that lead to particle precipitation and, in particular, the scattering of protons as they interact with VLF emission and the scattering when the particle motion becomes nonadiabatic are considered. We compare the data on particle dynamics during geomagnetic disturbances of various kinds to determine whether the physical processes that lead to particle precipitation are a manifestation of the geoefficiency of a given magnetic storm or they are controlled by internal magnetospheric conditions.

Protons with energy of E P ≥ MeV under the earth’s radiation belts

Variations in fluxes of quasi-trapped energetic protons were studied on the basis of the data of the CORONAS-I satellite. These variations are characterized by an increase in the proton fluxes with EP ≥ 1 MeV both in the vicinity of the geomagnetic equator and in the high-latitude region of the magnetosphere. The analysis of structural features of the proton distributions in the regions at L ∼ 1–1.1; 3 < L < 4; and L > 4, was performed and made it possible to detect reliably the type of the proton flux increase in this region. The mechanisms of particle scattering leading to the precipitation of energetic protons under conditions of various types of geomagnetic disturbances are considered.

The solar particle enhancement of April 14–17, 1994 observed without flare signature

We present the results of measurements of the solar energetic particle (SEP) flows in the Earth polar caps obtained from KORONAS-I on April 14, 1994. The maximum energy of protons was 12 MeV and the maximum energy of electrons was 1.3 MeV. The asymmetry of the North-South flows was observed several hours after their peak intensity. We determined the propagation characteristics of SEP in the isotropic diffusion model. Although the SEP enhancement has not been related to the solar flaring event, the genetic relationship of this effect with one of the largest-scale dynamical events on the Sun measured from YOHKOH is obvious. The possible sources of particle acceleration are discussed.

Recurrent fast particle enhancements observed from KORONAS-I

Enhancements of protons with energiesEp=1–4.5 MeV were observed from the KORONAS-I satellite in the period from March to June 1994. They represent part of a long series of corotating particle enhancements registered by the ULYSSES spacecraft outside the ecliptic plane. An about 5-day nearly constant shift between the maximum times was recorded by the two space vehicles. The assumptions of acceleration area localization and fast proton propagation conditions in the heliosphere are discussed on the basis of a joint analysis of the results presented here and the related experimental data.

Precipitation of electrons after geomagnetic substorms

РезюмеПрове¶rt;ен aнaлuз высыnaющuхся элекmронов Ee>10 кэВ u Ee>30 кэВ u nроmонов Ep=150−300 кэВ nо uзмеренuям nолученным с нuзкоорбumaльного сnуmнuкa с nолярноŭ орбumоŭ Инmеркосмос-17 nосле мaгнumноŭ бурu 2. ¶rt;екaбря 1977г. 3. 12. nроuзошлa uзолuровaннaя суббуря u сuлъное высыnaнuе элекmронов было зaрегuсmрuровaно в ночном секmоре месmногo временu. Временнaя nосле¶rt;овamелъносmъ суббуръ 5. 12. nрuвелa к рaсщuренuю ¶rt;олгоmного uнmервaлa, в коmором элекmроны высыnaлuсъ, a uменно оm 22 MLT через уmреннuŭ секmор ¶rt;о 12 MLT. Рaзныŭ хaрaкmер высыnaнuя в nрuве¶rt;енных ¶rt;вух случaях обсуж¶rt;aеmся в рaмкaх uзмененuŭ условuŭ ¶rt;ля вознuкновенuя цuклоmронноŭ неусmоŭчuвосmu u всле¶rt;сmвuе uнжекцuu чaсmuц. Высыnaнuе nроmонов nрохо¶rt;uло mоляко в ночном секmоре u верояmно зa nлaзмanaузоŭ внуmрu nрaзмaсферы.SummaryPrecipitating electrons Ee>10 keV and Ee>30 keV and protons Ep=150 to 300 keV are analyzed using data obtained from the low-altitude polar-orbiting satellite Interkozmos-17 after the magnetic storm of December 2, 1977. On December 3, an isolated substrom occurred, and strong electron precipitation was observed in the midnigt sector, while the sequence of substorms of December 5 expanded its longitudinal extent from 22 MLT through the morning to 12 MLT. The different character of the precipitation, in the two cases mentioned, is discussed in relation to the changes of conditions for the generation of cyclotron instability as well as to the effect of particle injection. Proton precipitation occurred only in the night sector, most probably just inside the plasmapause.

Correlated Cosmos-900 and Intercosmos-17 observations of spatial-temporal variations of ionospheric parameters and ring current ion precipitations

Abstract The data of simultaneous Cosmos-900, Intercosmos-17 measurements of 100-keV ions and cold plasma density and electron temperature are analyzed. The dynamics and the mutual position of the ionospheric trough and the ring-current ion precipitation regions during a strong magnetic storm in the dusk-dawn sector of the magnetosphere are studied.