Speaker
Description
The ambient solar wind plays an important role as one of the driver of geoeffective space weather activity. The solar magnetic field is 'frozen-in' and carried outward by the solar wind plasma. As it frozen-in, it follows the parker spiral. Usually 4-5 sectors of opposite polarity are present in the Interplanetary medium. Sector boundaries are the regions where the magnetic field direction changes rapidly. As the Sun rotates its sector structure — large-scale magnetic regions — rotates with it, fluctuations in the interplanetary magnetic field (IMF) in the near-Earth environment. When these variations in IMF orientation encounter Earth's magnetosphere, they can trigger Geomagnetic storms. Besides this, Solar wind also exhibits the Periodic Density Structures (PDSs) that are quasi-periodic fluctuations in the solar wind's density. PDSs advect with the solar wind and have radial scales of 10-1000 Mm . The periodic variations in solar wind density and dynamic pressure can drive oscillations in the magnetosphere, influencing geomagnetic activity and space weather [Di Matteo et al 2024] . Therefore, understanding their spatial extent, and IMF characteristics is vital.
Aditya-L1 is India's first solar observatory at the Sun-Earth L1 point which was successfully inserted into its halo orbit on January 6, 2024. Currently we are analysing the data from Aditya’s L1 insitu MAG and ASPEX payloads. Our goal is to characterize magnetic field and study turbulence, as well as solar wind ion velocities and density distributions. The long term data collected will be used to significantly enhance our understanding of anisotropies, shocks, and radial scales of solar wind periodic density structures (PDSs). We're have developed the ASPEX pdata processing pipeline. In the ESWW, we will present the results on Solar Wind PDSs structures derived from the solar wind density, time data-series measured from Jan 2024 till May 2025 by ASPEX payload onboard AdtiyaL1 spacecraft. We hope these results and methodologies will greatly benefit the Vigil mission too.
Nevertheless, measurements from a single spacecraft limits our capability to determine density and magnetic structures only along the radial Sun-Earth line (Lx). In order to observe the entire 3D expanse and size scales perpendicular to the Sun–Earth line (Ly), we need interplanetary multispacecraft observations capable of coherently and continuously measuring the solar wind at spatial separation perpendicular to the radial direction. In this scenario, Vigil mission, at L5 point that is located ~ 60 deg azimuthally behind wrt L1 point will be very useful.
A dual-point in-situ observation strategy, leveraging density and magnetic field measurements from both L1 and L5, might enable us to assess dimensions of solar wind PDSs , magnetic structures as well as their temporal evolution and fluctuation at the IMF sector boundaries when they cross these two crucial Lagrange points.
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