Related papers: The source of the 2017 cosmic ray half-year modula…
Solar coronal dimmings have been observed extensively in the past two decades. Due to their close association with coronal mass ejections (CMEs), there is a critical need to improve our understanding of the physical processes that cause…
One of the very common in situ signatures of interplanetary coronal mass ejections (ICMEs), as well as other interplanetary transients, are Forbush decreases (FDs), i.e. short-term reductions in the galactic cosmic ray (GCR) flux. A…
The sudden short duration decrease in cosmic ray flux is known as Forbush decrease which is mainly caused by interplanetary disturbances. Generally accepted view is that the first step of Forbush decrease is due to shock sheath and second…
The last solar minimum activity period, and the consequent minimum modulation conditions for cosmic rays, was unusual. The highest levels of galactic protons were recorded at Earth in late 2009 in contrast to expectations. Proton spectra…
The solar wind, when measured close to 1 au, is found to flow mostly radially outward. There are, however, periods when the flow makes angles up to 15$^\circ$ away from the radial direction, both in the east-west and north-south directions.…
The planetary hypothesis of the solar cycle is an old idea in which the gravitational influence of the planets has a non-negligible effect on the causes of the solar magnetic cycle. In this work we looked for a possible causal link in…
Similar to the Sun, other stars shed mass and magnetic flux via ubiquitous quasi-steady wind and episodic stellar coronal mass ejections (CMEs). We investigate the mass loss rate via solar wind and CMEs as a function of solar magnetic…
In our own solar system, the necessity of understanding space weather is readily evident. Fortunately for Earth, our nearest stellar neighbor is relatively quiet, exhibiting activity levels several orders of magnitude lower than young,…
We report on the parallel analysis of the periodic behaviour of coronal mass ejections (CMEs) based on 21 years [1996 -- 2016] of observations with the SOHO/LASCO--C2 coronagraph, solar flares, prominences, and several proxies of solar…
We report on the solar and interplanetary (IP) causes of the third largest geomagnetic storm (2018 August 26) in solar cycle 24. The underlying coronal mass ejection (CME) originating from a quiescent filament region becomes a 440 km/s…
This paper presents the global analysis of two extended decreases of the galactic cosmic ray intensity observed by world-wide networks of ground-based detectors in 2012. This analysis is capable of separately deriving the cosmic ray density…
We seek to estimate the average level of MHD turbulence near coronal mass ejection (CME) fronts as they propagate from the Sun to the Earth. We examine the cosmic ray data from the GRAPES-3 tracking muon telescope at Ooty, together with the…
Solar flares (SFs) are sudden brightening observed over the Sun surface which is associated with a large energy release. Flares with burst of Xray emission are normally followed by a mass ejection of electrons and ions from the solar…
The meridional circulation of the Sun is observationally found to vary with the solar cycle, becoming slower during the solar maxima. We explain this by constructing a theoretical model in which the equation of the meridional circulation…
As galactic cosmic rays propagate through the turbulent plasma environment within the heliosphere, they undergo a process of diffusion, drift and energy loss, leading to a notable reduction in their flux. This is the solar modulation…
The AMS02 collaboration has recently published high precision daily measurements of the spectra of cosmic ray protons, helium nuclei and electrons taken during a time interval of approximately 10 years from 2011 to 2020. Positron spectra…
Protons detected by the PAMELA experiment in the period 2006-2014 have been analyzed in the energy range between 0.40-50 GV to explore possible periodicities besides the well known solar undecennial modulation. An unexpected clear and…
Loss of equilibrium of magnetic flux ropes is a leading candidate for the origin of solar coronal mass ejections (CMEs). The aim of this paper is to explore to what extent this mechanism can account for the initiation of CMEs in the global…
Coronal mass ejections (CMEs) have become one of the key indicators of solar activity, especially in terms of the consequences of the transient events in the heliosphere. Although CMEs are closely related to the sunspot number (SSN), they…
We report the ground-level detection of a Galactic Cosmic-Ray (GCR) flux enhancement lasting $\sim$ 17 hr and associated with the passage of a magnetic flux rope (MFR) over the Earth. The MFR was associated with a slow Coronal Mass Ejection…