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

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.more » As a result, 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.« less

Authors:

McComas, David J.  ^[1];

• Search DOE PAGES for author "McComas, David J."
• Search DOE PAGES for ORCID "0000-0002-9745-3502"

Dayeh, M. A. ^[2]; Funsten, Herbert O.  ^[3];

• Search DOE PAGES for author "Funsten, Herbert O."
• Search DOE PAGES for ORCID "0000-0002-6817-1039"

Heerikhuisen, Jacob ^[4]; Janzen, P. H. ^[5]; Reisenfeld, Daniel B.  ^[5];

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• Search DOE PAGES for ORCID "0000-0003-1874-9450"

Schwadron, Nathan A.  ^[6];

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• Search DOE PAGES for ORCID "0000-0002-3737-9283"

Szalay, J. R.  ^[1];

• Search DOE PAGES for author "Szalay, J. R."
• Search DOE PAGES for ORCID "0000-0003-2685-9801"

Zirnstein, Eric J.  ^[1]

• Search DOE PAGES for author "Zirnstein, Eric J."
• Search DOE PAGES for ORCID "0000-0001-7240-0618"

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+ Show Author Affiliations

1. Princeton Univ., Princeton, NJ (United States)
2. Southwest Research Institute, San Antonio, TX (United States)
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
4. Univ. of Alabama in Huntsville, Huntsville, AL (United States)
5. Univ. of Montana, Missoula, MT (United States)
6. Univ. of New Hampshire, Durham, NH (United States)

Publication Date:

Tue Mar 20 00:00:00 EDT 2018

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautics and Space Administration (NASA); USDOE

OSTI Identifier:

1542836

Report Number(s):

LA-UR-18-26712
Journal ID: ISSN 2041-8213

Grant/Contract Number:  

89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal. Letters (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal. Letters (Online); Journal Volume: 856; Journal Issue: 1; Journal ID: ISSN 2041-8213

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; local interstellar matter; solar wind; Sun: activity; Sun: heliosphere; Sun: magnetic fields