A Predicted Small and Round Heliosphere. (arXiv:1808.06611v2 [physics.space-ph] UPDATED)
<a href="http://arxiv.org/find/physics/1/au:+Opher_M/0/1/0/all/0/1">Merav Opher</a>, <a href="http://arxiv.org/find/physics/1/au:+Loeb_A/0/1/0/all/0/1">Abraham Loeb</a>, <a href="http://arxiv.org/find/physics/1/au:+Drake_J/0/1/0/all/0/1">James Drake</a>, <a href="http://arxiv.org/find/physics/1/au:+Toth_G/0/1/0/all/0/1">Gabor Toth</a>
The shape of the solar wind bubble within the interstellar medium, the
so-called heliosphere, has been explored over six decades. As the Sun moves
through the surrounding partially-ionized medium, neutral hydrogen atoms
penetrate the heliosphere, and through charge-exchange with the supersonic
solar wind, create a population of hot pick-up ions (PUIs). The Termination
Shock (TS) crossing by Voyager 2 (V2) data demonstrated that the heliosheath
(HS) (the region of shocked solar wind) pressure is dominated by suprathermal
particles. Here we use a novel magnetohydrodynamic model that treats the
freshly ionized PUIs as a separate fluid from the thermal component of the
solar wind. Unlike previous models, the new model reproduces the properties of
the PUIs and solar wind ions based on the New Horizon and V2 spacecraft
observations. The PUIs charge exchange with the cold neutral H atoms of the ISM
in the HS and are quickly depleted. The depletion of PUIs cools the heliosphere
downstream of the TS, “deflating” it and leading to a narrower HS and a smaller
and rounder shape, in agreement with energetic neutral atom observations by the
Cassini spacecraft. The new model, with interstellar magnetic field orientation
constrained by the IBEX ribbon, reproduces the magnetic field data outside the
HP at Voyager 1(V1). We present the predictions for the magnetic field outside
the HP at V2.
The shape of the solar wind bubble within the interstellar medium, the
so-called heliosphere, has been explored over six decades. As the Sun moves
through the surrounding partially-ionized medium, neutral hydrogen atoms
penetrate the heliosphere, and through charge-exchange with the supersonic
solar wind, create a population of hot pick-up ions (PUIs). The Termination
Shock (TS) crossing by Voyager 2 (V2) data demonstrated that the heliosheath
(HS) (the region of shocked solar wind) pressure is dominated by suprathermal
particles. Here we use a novel magnetohydrodynamic model that treats the
freshly ionized PUIs as a separate fluid from the thermal component of the
solar wind. Unlike previous models, the new model reproduces the properties of
the PUIs and solar wind ions based on the New Horizon and V2 spacecraft
observations. The PUIs charge exchange with the cold neutral H atoms of the ISM
in the HS and are quickly depleted. The depletion of PUIs cools the heliosphere
downstream of the TS, “deflating” it and leading to a narrower HS and a smaller
and rounder shape, in agreement with energetic neutral atom observations by the
Cassini spacecraft. The new model, with interstellar magnetic field orientation
constrained by the IBEX ribbon, reproduces the magnetic field data outside the
HP at Voyager 1(V1). We present the predictions for the magnetic field outside
the HP at V2.
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