Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX

D. J. McComas, M. A. Dayeh, H. O. Funsten, J. Heerikhuisen, P. H. Janzen, D. B. Reisenfeld, N. A. Schwadron, J. R. Szalay, E. J. Zirnstein

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

Our heliosphere - the bubble in the local interstellar medium produced by the Sun's outflowing solar wind - has finally responded to a large increase in solar wind output and pressure in the second half of 2014. NASA's Interstellar Boundary Explorer (IBEX) mission remotely monitors the outer heliosphere by observing energetic neutral atoms (ENAs) returning from the heliosheath, the region between the termination shock and heliopause. IBEX observed a significant enhancement in higher energy ENAs starting in late 2016. While IBEX observations over the previous decade reflected a general reduction of ENA intensities, indicative of a deflating heliosphere, new observations show that the large (∼50%), persistent increase in the solar wind dynamic pressure has modified the heliosheath, producing enhanced ENA emissions. The combination of these new observations with simulation results indicate that this pressure is re-expanding our heliosphere, with the termination shock and heliopause already driven outward in the locations closest to the Sun. The timing between the IBEX observations, a large transient pressure enhancement seen by Voyager 2, and the simulations indicates that the pressure increase propagated through the heliosheath, reflected off the heliopause, and the enhanced density of the solar wind filled the heliosheath behind it before generating significantly enhanced ENA emissions. The coming years should see significant changes in anomalous cosmic rays, galactic cosmic radiation, and the filtration of interstellar neutral atoms into the inner heliosphere.

Original languageEnglish (US)
Article numberL10
JournalAstrophysical Journal Letters
Volume856
Issue number1
DOIs
StatePublished - Mar 20 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Sun: activity
  • Sun: heliosphere
  • Sun: magnetic fields
  • local interstellar matter
  • solar wind

Fingerprint Dive into the research topics of 'Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX'. Together they form a unique fingerprint.

  • Cite this

    McComas, D. J., Dayeh, M. A., Funsten, H. O., Heerikhuisen, J., Janzen, P. H., Reisenfeld, D. B., Schwadron, N. A., Szalay, J. R., & Zirnstein, E. J. (2018). Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX. Astrophysical Journal Letters, 856(1), [L10]. https://doi.org/10.3847/2041-8213/aab611