Pluto's interaction with the solar wind

Academic Article


  • AbstractThis study provides the first observations of Plutogenic ions and their unique interaction with the solar wind. We find ~20% solar wind slowing that maps to a point only ~4.5 RP upstream of Pluto and a bow shock most likely produced by comet‐like mass loading. The Pluto obstacle is a region of dense heavy ions bounded by a “Plutopause” where the solar wind is largely excluded and which extends back >100 RP into a heavy ion tail. The upstream standoff distance is at only ~2.5 RP. The heavy ion tail contains considerable structure, may still be partially threaded by the interplanetary magnetic field (IMF), and is surrounded by a light ion sheath. The heavy ions (presumably CH4+) have average speed, density, and temperature of ~90 km s−1, ~0.009 cm−3, and ~7 × 105 K, with significant variability, slightly increasing speed/temperature with distance, and are N‐S asymmetric. Density and temperature are roughly anticorrelated yielding a pressure ~2 × 10−2 pPa, roughly in balance with the interstellar pickup ions at ~33 AU. We set an upper bound of <30 nT surface field at Pluto and argue that the obstacle is largely produced by atmospheric thermal pressure like Venus and Mars; we also show that the loss rate down the tail (~5 × 1023 s−1) is only ~1% of the expected total CH4 loss rate from Pluto. Finally, we observe a burst of heavy ions upstream from the bow shock as they are becoming picked up and tentatively identify an IMF outward sector at the time of the NH flyby.
  • Authors

  • McComas, DJ
  • Elliott, HA
  • Weidner, S
  • Valek, P
  • Zirnstein, EJ
  • Bagenal, F
  • Delamere, PA
  • Ebert, RW
  • Funsten, HO
  • Horanyi, M
  • McNutt, RL
  • Moser, C
  • Schwadron, Nathan
  • Strobel, DF
  • Young, LA
  • Ennico, K
  • Olkin, CB
  • Stern, SA
  • Weaver, HA
  • Status

    Publication Date

  • May 2016
  • Published In


  • Pluto
  • Plutopause
  • bow shock
  • heavy ion tail
  • pickup ions
  • solar wind interaction
  • Digital Object Identifier (doi)

    Start Page

  • 4232
  • End Page

  • 4246
  • Volume

  • 121
  • Issue

  • 5