The event of 2021 April 23-25

In the early hours of 2021 April 25, the SPC on-board PSP registered the passage of a solar wind structure characterized by a clear and constant alpha to proton density ratio above 6\% during three hours. The alpha contribution remained present but faint and intermittently within a twelve-hour window. 

In this work, we report the helium-enriched plasma structure from the Sun to PSP combining multi-spacecraft remote sensing and in situ measurements. We identified as source, a prominence origin visible in both STA/EUVI and SO/EUI. Except for the extraordinary alpha ratio enhancement, the CME showed ordinary plasma signatures and a magnetic field configuration that did not permit the identification of its physical boundaries. We believe this to be the first example of a CME being imaged by WISPR directly before and during being detected in situ. 

Studying the evolution and propagation of a prominent solar wind structure observed by PSP on June 13, 2020

In the early hours of June 13, 2020, just after the end of its 5th solar encounter, the Faraday Cup on-board PSP registered the passage of a prominent solar wind structure embedded in highly variable plasma and characterized by regions with distinct plasma conditions (speed, density, magnetic field, etc) and wave activity. From remote sensing observations, using spacecraft at different heliospheric locations, several transients were observed ejected from the Sun, including a coronal mass ejection (CME) oriented away from PSP that may have also influenced the solar wind conditions through which the structure in question has propagated. In this work, we report the PSP-SPC observations around this structure and identify possible solar sources relying on multi-spacecraft observations. We also characterized the propagation and evolution of the CME observed on June 12, 2020 and the role it played influencing the conditions of the unusual variable ambient solar wind.

Observation and modeling of an geo-effective event observed on 2011 May 28 from the solar surface to 1AU

In this study, we present a comprehensive observational and modeling of a geo-effective event (Dst index in -80 nT) observed on 2011 May 28 when a coronal hole was bordering an active region. We combine remote sensing and in situ measurements to identify the different sources of the solar wind measured by Wind spacecraft and perform analytical and numerical models to track the CME/ICME propagation up to 1 AU and study its magnetic field configuration.

Helium abundance and non-equilibrium in the inner heliosphere in PSP

In this work, we combine simultaneous measurements from the Faraday Cup and electrostatic analyzers in order to disentangle the two species:  the hydrogen and helium components in the SPC measurements.

Evolution and propagation of coronal mass ejections through the interplanetary medium

We investigate through analytical and numerical hydrodynamical models the propagation of a single CME into the solar wind, as well as ICME–ICME interaction events. 

We can predict the travel time, speed and density of the ICMEs/merged region at any heliospheric distance and the in situ parameter time-profiles observed at 1 AU.

Radio emissions during coronal mass ejection interactions 

We associate sporadic radio emissions to the interaction between two interplanetary coronal mass ejections.  We simulate the evolution of the interacting ICMEs and identified local density structures and associated speed enhancements which may be the source of these sporadic radio emissions.  With this analysis we show that this kind of sporadic emissions are good tracers of the ICME-ICME interaction.