Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind.
The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values <1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.
Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA.|Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA.
Noé
N
Lugaz
Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA.|Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA.
Charles J
CJ
Farrugia
Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA.|Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA.
Chia-Lin
CL
Huang
Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA.
Reka M
RM
Winslow
Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA.|Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA.
Harlan E
HE
Spence
Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA.|Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA.
Nathan A
NA
Schwadron
J Geophys Res Space Phys. 2013 Aug;118(8):4952-4962
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