Influence Of Coronal Mass Ejections Research Articles

Influence of helio-geophysical activity on reliability of short-wave communication in transport

The results of studies of the influence of coronal mass ejections and high-velocity solar wind streams on the characteristics of the ionosphere are presented. The analysis uses ionospheric data from the CADI vertical sounding station (Vasilsursk, Nizhny Novgorod region) and data from chirp stations for oblique ionospheric sounding on different paths of the Eurasian region of Russia: three subauroral (Lovozero-Vasilsursk, Sodankyulya-Vasilsursk and Salekhard-Vasilsursk) and one mid-latitude (Gorky, Leningrad region-Vasilsursk). A set of space weather parameters (type and speed of coronal mass ejections, high-speed solar wind speed) is considered, which made it possible to reveal the dominant physical relationships between the ionospheric dynamics and these two solar phenomena, which determine the reliability of short-wave radio communication between ships and the coast, especially in the area of the northern sea way.

The impact of coronal mass ejection on the horizontal geomagnetic fields and the induced geoelectric fields

This work investigates the influence of coronal mass ejection (CME) on the time derivatives of horizontal geomagnetic and geoelectric fields, proxy parameters for identifying GICs. 16 events were identified for the year 2003 from the CORONAS-PHOTON spacecraft. Five of the events (May 29, June 9, October 28, October 29, and November 4) were extensively discussed over four magnetic observatories, were analyzed using the time derivatives of the horizontal geomagnetic (dH/dt) and geoelectric (EH) fields obtained from data of the INTERMAGNET network. It was observed that energy distributions of the wavelet power spectrum of the horizontal geoelectric field are noticed at the nighttime on both 29 May and 9 June 2003 across the stations. Daytime and nighttime intensification of energy distribution of the wavelet power spectrum of the horizontal geoelectric field are observed on both 28 and 29 October 2003 due to strong westward electrojet. The 4 November 2003 event depicts daytime amplification of energy distributions of the wavelet power spectrum across the stations. The highest correlation magnitude is obtained in the event of 4 November 2003 between dH/dt and EH relationships during the intense solar flare of class X 17.4. We observed that the correlation magnitude between dH/dt and EH increases with increase in CME activity. We concluded that the response of the surface impedance model for different stations plays a key role in determining the surface electric field strength, due to large electric field changes at different stations.

The Influence of Coronal Mass Ejections on the Mass-loss Rates of Hot-Jupiters

Abstract Hot-Jupiters are subject to extreme radiation and plasma flows coming from their host stars. Past ultraviolet Hubble Space Telescope observations, supported by hydrodynamic models, confirmed that these factors lead to the formation of an extended envelope, part of which lies beyond the Roche lobe. We use gas-dynamic simulations to study the impact of time variations in the parameters of the stellar wind, namely that of coronal mass ejections (CMEs), on the envelope of the typical hot-Jupiter HD 209458b. We consider three CMEs characterized by different velocities and densities, taking their parameters from typical CMEs observed for the Sun. The perturbations in the ram-pressure of the stellar wind during the passage of each CME tear off most of the envelope that is located beyond the Roche lobe. This leads to a substantial increase of the mass-loss rates during the interaction with the CME. We find that the mass lost by the planet during the whole crossing of a CME is of ≈1015 g, regardless of the CME taken into consideration. We also find that over the course of 1 Gyr, the mass lost by the planet because of CME impacts is comparable to that lost because of high-energy stellar irradiation.

The influence of coronal mass ejections on the gas dynamics of the atmosphere of a “hot Jupiter” exoplanet

The results of three-dimensional numerical simulations of the gas dynamics of the atmosphere of a "hot Jupiter" exoplanet during the passage of a coronal mass ejection (CME) from the central star are presented. These computations assumed the parameters for the stellar wind and the CME to be typical of the solar values. The characteristic variations of the flow pattern are considered for quasi-closed and closed (but appreciably distorted by the gravitational influence of the star) gaseous envelopes of the exoplanet. It is shown that a typical CME is sufficient to tear off the outer part of an asymmetric envelope that is located beyond the Roche lobe and carry it away from the exoplanet. This leads to a substantial increase in the mass-loss rate from the exoplanet envelope during the passage of CMEs. The mass-loss rate grows by about a factor of 11 for a closed envelope, and by about a factor of 14 for a quasi-closed envelope. Possible evolutionary consequences of the loss of part of the atmosphere during the passage of CMEs are discussed.

Influence of coronal mass ejection on geomagnetic activity during 1988–1993

The most rapid and dramatic evolution in the solar corona occurs in events now known as Coronal Mass Ejections (CMEs). There have considerable importance for our understanding of the evolution of the mass and energy injected into the interplanetary medium. In this work, we have studied the relation of CMEs with geomagnetic activity for the period of 1988 to 1993. Not all CMEs are capable of producing geomagnetic disturbances. Our study indicates that the maximum chance of a geomagnetic disturbance occurs two to three days after a CME in association with B-type solar flares.

Study of interrelations between solar energetic particle events, solar flares and coronal mass ejections

In the last few years the new paradigm of causal relations of active processes in solar atmosphere and interplanetary space is actively propagated. According to it large and long duration solar energetic particle (SEP) events are produced by coronal mass ejections (CMEs), not by solar flares. Nowadays this seems evident for 105 – 107 eV protons but energetic electrons are still considered to be accelerated exclusively in impulsive phase of solar flares. We discuss the results of the analysis of interrelations between electron component of SEP-events, flares and CMEs on the basis of SEP-event observations onboard various s/c at radial distances of 0.3–1.5 AU during the period 1979–1989. Statistics includes about 68 events related to CUE-flare associations. Dependences of SEP-event time-scales and spectra of 0.03–1.5 MeV electrons on CME speeds and angular widths were considered. Energy spectra of electrons become harder with CUE speed increasing and the spectral exponent γ ∝V−0.5 . More than 20 events were observed simultaneously at various points of the inner heliosphere and the results of multispacecraft observations permit us to consider influence of CME -driven shocks on electron fluxes at various azimutal angles relative to shock nose.

Influence of Coronal Mass Ejections from the Red Dwarf Component on the Accretion Pattern in CVs and LMXBs

Low-mass main sequence stars show a magnetic activity similar to the Sun and as a consequence they lose mass in the form of a variable stellar wind. In the latest spectral types (red dwarfs) the activity and the mass loss rate appear to increase by a large factor of ∼ 103 with respect to the solar case, reaching Ṁ ∼ 2 · 10−11 M⊙/yr (Badalyan & Livshits 1992, Katsova 1993). The same happens for coronal mass ejections (CMEs), which are the most relevant transient events of mass loss in these objects. In the Sun, these appear as bubbles of coronal material, with dimensions of some fraction of the solar surface, mass M ≃ 2 · 1014 - 2 · 1016 g and ejection velocity v ≃ 3 · 107 - 2 · 108 cm/s, with an instantaneous mass loss rate Ṁ ∽ 10−13 - 10−11 M⊙/yr (Wagner 1984). In red dwarfs, as recently observed, the ejection velocities are higher, up to v ≃ 3 · 108 cm/s and the mass loss rate can reach the value Ṁ ≃ 10−8 M⊙/yr (Mullan et al. 1989, Houdebine et al. 1990). In both cases, the observations suggest that a bubble expands, once ejected, with a velocity of several hundreds of km/s.