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Title: Local interstellar magnetic field determined from the interstellar boundary explorer ribbon

The solar wind emanating from the Sun interacts with the local interstellar medium (LISM), forming the heliosphere. Hydrogen energetic neutral atoms (ENAs) produced by the solar-interstellar interaction carry important information about plasma properties from the boundaries of the heliosphere, and are currently being measured by NASA's Interstellar Boundary Explorer (IBEX). IBEX observations show the existence of a “ribbon” of intense ENA emission projecting a circle on the celestial sphere that is centered near the local interstellar magnetic field (ISMF) vector. Here we show that the source of the IBEX ribbon as a function of ENA energy outside the heliosphere, uniquely coupled to the draping of the ISMF around the heliopause, can be used to precisely determine the magnitude (2.93 ± 0.08 μG) and direction (227.°28 ± 0.°69, 34.°62 ± 0.°45 in ecliptic longitude and latitude) of the pristine ISMF far (~1000 AU) from the Sun. We find that the ISMF vector is offset from the ribbon center by ~8.°3 toward the direction of motion of the heliosphere through the LISM, and their vectors form a plane that is consistent with the direction of deflected interstellar neutral hydrogen, thought to be controlled by the ISMF. Lastly, our results yield draped ISMFmore » properties close to that observed by Voyager 1, the only spacecraft to directly measure the ISMF close to the heliosphere, and give predictions of the pristine ISMF that Voyager 1 has yet to sample.« less
ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [1] ;  [4] ; ORCiD logo [2]
  1. Southwest Research Inst. (SwRI), San Antonio, TX (United States)
  2. Univ. of Alabama, Huntsville, AL (United States). Dept. of Space Science
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Southwest Research Inst. (SwRI), San Antonio, TX (United States); Univ. of Texas, San Antonio, TX (United States)
Publication Date:
Grant/Contract Number:
SC0008334; NNX14AJ53G; NNX14AF43G; NNX15AN72G; OCI-1144120
Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 818; Journal Issue: 1; Journal ID: ISSN 2041-8213
Institute of Physics (IOP)
Research Org:
Univ. of Alabama, Huntsville, AL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); National Aeronautic and Space Administration (NASA); National Science Foundation (NSF)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; ISM: atoms; ISM: magnetic fields; solar wind; Sun: heliosphere
OSTI Identifier: