Multi-source connectivity as the driver of solar wind variability in the heliosphere

Stephanie L Yardley; David H Brooks; Raffaella D'Amicis; Christopher J Owen; David M Long; Deb Baker; Pascal Démoulin; Mathew J Owens; Mike Lockwood; Teodora Mihailescu; Jesse T Coburn; Ryan M Dewey; Daniel Müller; Gabriel H H Suen; Nawin Ngampoopun; Philippe Louarn; Stefano Livi; Sue Lepri; Andrzej Fludra; Margit Haberreiter; Udo Schühle

doi:10.1038/s41550-024-02278-9

Multi-source connectivity as the driver of solar wind variability in the heliosphere

Nat Astron. 2024;8(8):953-963. doi: 10.1038/s41550-024-02278-9. Epub 2024 May 28.

Authors

Stephanie L Yardley^{1

2

3

4}, David H Brooks⁵, Raffaella D'Amicis⁶, Christopher J Owen³, David M Long⁷, Deb Baker³, Pascal Démoulin^{8

9}, Mathew J Owens², Mike Lockwood², Teodora Mihailescu³, Jesse T Coburn³, Ryan M Dewey¹⁰, Daniel Müller¹¹, Gabriel H H Suen³, Nawin Ngampoopun³, Philippe Louarn¹², Stefano Livi^{10

13}, Sue Lepri¹⁰, Andrzej Fludra¹⁴, Margit Haberreiter¹⁵, Udo Schühle¹⁶

Affiliations

¹ Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne, UK.
² Department of Meteorology, University of Reading, Reading, UK.
³ Department of Space and Climate Physics, UCL Mullard Space Science Laboratory, Holmbury St Mary, UK.
⁴ Donostia International Physics Center (DIPC), San Sebastián, Spain.
⁵ Department of Physics & Astronomy, George Mason University, Fairfax, VA USA.
⁶ INAF-Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy.
⁷ School of Physical Sciences, Dublin City University, Dublin, Ireland.
⁸ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France.
⁹ Laboratoire Cogitamus, Paris, France.
¹⁰ Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI USA.
¹¹ European Space Agency, ESTEC, Noordwijk, The Netherlands.
¹² Institut de Recherche en Astrophysique et Planétologie, Toulouse, France.
¹³ Present Address: Southwest Research Institute, San Antonio, TX USA.
¹⁴ RAL Space, UKRI STFC Rutherford Appleton Laboratory, Chilton, UK.
¹⁵ Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Davos Dorf, Switzerland.
¹⁶ Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany.

Abstract

The ambient solar wind that fills the heliosphere originates from multiple sources in the solar corona and is highly structured. It is often described as high-speed, relatively homogeneous, plasma streams from coronal holes and slow-speed, highly variable, streams whose source regions are under debate. A key goal of ESA/NASA's Solar Orbiter mission is to identify solar wind sources and understand what drives the complexity seen in the heliosphere. By combining magnetic field modelling and spectroscopic techniques with high-resolution observations and measurements, we show that the solar wind variability detected in situ by Solar Orbiter in March 2022 is driven by spatio-temporal changes in the magnetic connectivity to multiple sources in the solar atmosphere. The magnetic field footpoints connected to the spacecraft moved from the boundaries of a coronal hole to one active region (12961) and then across to another region (12957). This is reflected in the in situ measurements, which show the transition from fast to highly Alfvénic then to slow solar wind that is disrupted by the arrival of a coronal mass ejection. Our results describe solar wind variability at 0.5 au but are applicable to near-Earth observatories.

Keywords: Solar physics; Space physics.