1. Study of flux-rope characteristics at sub-astronomical-unit distances using the Helios 1 and 2 spacecraft
- Author
-
Wageesh Mishra, Ake Zao, Anil Raghav, Yuming Wang, Zubair I Shaikh, and Sandesh Gaikwad
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,Spacecraft ,business.industry ,Astronomical unit ,Flux ,Astronomy ,Astronomy and Astrophysics ,HeliOS ,01 natural sciences ,Solar wind ,Space and Planetary Science ,Physics::Space Physics ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,business ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Rope - Abstract
Magnetic flux ropes observed as magnetic clouds near 1 au have been extensively studied in the literature and their distinct features are derived using numerous models. These studies summarize the general characteristics of flux ropes at 1 au without providing an understanding of the continuous evolution of the flux ropes from near the Sun to 1 au. In the present study, we investigate 26 flux ropes observed by the Helios 1 and 2 spacecraft (from 0.3 to 1 au) using the velocity-modified Gold–Hoyle model. The correlation and regression analyses suggest that the expansion speed, poloidal speed, total magnetic helicity and twist per au of the flux rope are independent of heliospheric distance. The study implies that the aforementioned features are more strongly influenced by their internal properties compared with external conditions in the ambient medium. Moreover, the poloidal magnetic flux and magnetic energy of the studied flux ropes exhibit power-law dependence on heliospheric distance. A better understanding of the underlying physics and corroboration of these results is expected from the Parker Solar Probe measurements in the near future.
- Published
- 2020