The dearth of observations between 1 au and 3 au limits our understanding of energetic particle acceleration processes in interplanetary space. We present the first-of-their-kind observations of the energetic particle acceleration in a Corotating Interaction Region (CIR) using data from two vantage points, 1 au (near Earth) and 1.5 au (near Mars). The CIR event of June 2015 was observed by the particle detectors aboard the Advanced Composition Explorer (ACE) satellite as well as the SEP (Solar Energetic Particle) instrument aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft situated near 1.5 au. We find that a CIR shock can accelerate a significant number of particles even at 1.5 au. During this event the acceleration by the shocks associated with the CIR could cause an enhancement of around two orders of magnitude in the SEP energetic ion fluxes in the ~500 keV to 2 MeV range when the observations near 1 and 1.5 au are compared. To demonstrate the differences between SEP acceleration in CIR and other impulsive events, we show the energetic ion flux observations during an intense CME period in March 2015, in which case the enhanced SEP fluxes are seen even at 1 au. These observations provide evidence that CIR shock can accelerate particles in the region between Earth and Mars, that is, only within the short heliocentric distance of 0.5 au, in interplanetary space.
The response of Martian ionosphere to the passage of Corotating Interaction Region (CIR) of June 2015 is studied using observations from several instruments aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. An intense CIR arrived at Mars on 22 June 2015, during which the upstream solar wind and interplanetary conditions were monitored by the Solar Wind Ion Analyzer (SWIA), Solar Wind Electron Analyzer (SWEA), Magnetometer (MAG), and Solar Energetic Particle (SEP) instruments aboard MAVEN. The CIR event was characterized by enhancements in solar wind density, velocity, and dyna…
We investigate energetic particle transport in Corotating Interaction Regions (CIRs) through a case study. The CIR event we study occurred on $2008$ February $08$ and was observed by both the Advanced Composition Explorer (ACE) and the twin Solar TErrestrial RElations Observatory (STEREO)-B spacecraft. An in-situ reverse shock was observed by STEREO-B ($1.0$ AU) but not ACE ($0.98$ AU). Using STEREO-B observations and assuming the CIR structure does not vary significantly in the corotating frame, we estimate the shock location at later times for both the STEREO-B and ACE observations. Further …
We introduce a new solar energetic particle (SEP) transport code that aims at studying the effects of different solar wind configurations on SEP events. We focus on the influence of varying solar wind velocities on the energy changes of SEPs, and study how a non-Parker background solar wind can trap particles temporarily at small heliocentric radial distances (r<1.5 AU). Our model computes particle distributions by solving the focused transport equation (FTE) in a stochastic manner by propagating particles in a solar wind generated by the heliospheric MHD model EUHFORIA. We solve the FTE, incl…
We present observations from the Rosetta Plasma Consortium of the effects of stormy solar wind on comet 67P/Churyumov-Gerasimenko. Four corotating interaction regions (CIRs), where the first event has possibly merged with a CME, are traced from Earth via Mars (using Mars Express and MAVEN) and to comet 67P from October to December 2014. When the comet is 3.1-2.7 AU from the Sun and the neutral outgassing rate $\sim10^{25}-10^{26}$ s$^{-1}$ the CIRs significantly influence the cometary plasma environment at altitudes down to 10-30 km. The ionospheric low-energy \textcolor{black}{($\sim$5 eV) pl…
August 1 to November 15, 2016 period was characterized by the presence of Corotating Interaction Regions (CIRs) and a few weak Coronal Mass Ejections (CMEs) in the heliosphere. In this study we show recurrent energetic electron and proton enhancements observed near Earth (1 AU) and Mars (1.43-1.38 AU) during this period. The observations near Earth are using data from instruments aboard ACE, SOHO, and SDO whereas those near Mars are by the SEP, SWIA, and MAG instruments aboard MAVEN. During this period, the energetic electron fluxes observed near Earth and Mars showed prominent periodic enhanc…
We report on a study that compares energetic particle fluxes in corotating interaction regions (CIRs) associated with type III radio storm with those in nonstorm CIRs. In a case study, we compare the CIR particle events on 2010October 21 and 2005 November 2. The two events have similar solar and solar wind circumstances, except that the former is associated with a type III radio storm and has a higher CIR particle flux and fluence. We also perform a statistical study, which shows that the proton and electron fluences are higher in the storm associated CIRs by factor of about 6 and 8, respectiv…
We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere, arranged by the angle between electric field vector and the projection of spacecraft position radius vector in the YZ plane in MSE coordinate system ($θ$ E ). All passes were divided into 3 angular sectors near 0°, 90° and 180° $θ$ E angles in order to estimate the role of IMF direction in plasma and magnetic properties of dayside Martian magnetosphere. The time interval chosen was from January 17 through February 4, 2016 when MAVEN was crossing the dayside magnetosphere at SZA ~ 70°. Magnetosphere as the region with prev…
The Parker Solar Probe was launched on 2018 August 12 and completed its second orbit on 2019 June 19 with perihelion of 35.7 solar radii. During this time, the Energetic particle Instrument-Hi (EPI-Hi, one of the two energetic particle instruments comprising the Integrated Science Investigation of the Sun, ISOIS) measured seven proton intensity increases associated with stream interaction regions (SIRs), two of which appear to be occurring in the same region corotating with the Sun. The events are relatively weak, with observed proton spectra extending to only a few MeV and lasting for a few d…
The Integrated Science Investigations of the Sun (IS$\odot$IS) instrument suite includes two Energetic Particle instruments: EPI-Hi, designed to measure ions from ~1-200 MeV/nuc, and EPI-Lo, designed to measure ions from ~20 keV/nuc to ~15 MeV/nuc. We present an analysis of eight energetic proton events observed across the energy range of both instruments during PSP's first two orbits in order to examine their combined energy spectra. Background corrections are applied to help resolve spectral breaks between the two instruments and are shown to be effective. In doing so we demonstrate that, ev…
Context. Interplanetary (IP) shocks are known to be accelerators of energetic charged particles observed in-situ in the heliosphere. However, the acceleration of near-relativistic electrons by shocks in the interplanetary medium is often questioned. On 9 August 2011 a Corotating Interaction Region (CIR) passed STEREO B (STB) that resulted in a flux increase in the electron and ion channels of the Solar Electron and Proton Telescope (SEPT). Because electron measurements in the few keV to several 100 keV range rely on the so-called magnet foil technique, which is utilized by SEPT, ions can contr…
Corotation of particle-filled magnetic flux tubes is generally thought to have a minor influence on the time-intensity profiles of gradual Solar Energetic Particle (SEP) events. For this reason many models solve the focussed transport equation within the corotating frame, thus neglecting corotation effects. We study the effects of corotation on gradual SEP intensity profiles at a range of observer longitudinal positions relative to the solar source. We study how corotation affects the duration and decay time constant of SEP events and the variation of peak intensity with observer position. We …
We study the effect of the magnetic gradient and curvature drifts on the pitch-angle dependent transport of solar energetic particles (SEPs), focusing on 3 - 36 MeV protons. By considering observers located at various positions in the heliosphere, we investigate how drifts may alter the measured intensity-time profiles and energy spectra. We focus on the decay phase of solar energetic proton events during which a temporal invariant spectrum and disappearing spatial intensity gradients are often observed; a phenomenon known as the 'reservoir effect' or the 'SEP flood'. We study the effects of d…
Using ion measurements from Ultra-Low-Energy Isotope Spectrometer (ULEIS) observations onboard Advanced Composition Explorer (ACE) and Solar Isotope Spectrometer (SIS) observations onboard the Solar Terrestrial Observatory (STEREO)-A and STEREO-B spacecraft, we have identified 854 3He-rich time periods between 1997 September and 2021 March. We include all event types with observed 3He enhancements such as corotating interaction regions (CIRs), gradual solar energetic particle (SEP) events, interplanetary shocks, and impulsive SEP events. We employ two different mass separation techniques to ob…
