skip to main content

Title: TRIANGULATION OF THE INTERSTELLAR MAGNETIC FIELD

Determining the direction of the local interstellar magnetic field (LISMF) is important for understanding the heliosphere’s global structure, the properties of the interstellar medium, and the propagation of cosmic rays in the local galactic medium. Measurements of interstellar neutral atoms by Ulysses for He and by SOHO/SWAN for H provided some of the first observational insights into the LISMF direction. Because secondary neutral H is partially deflected by the interstellar flow in the outer heliosheath and this deflection is influenced by the LISMF, the relative deflection of H versus He provides a plane—the so-called B–V plane in which the LISMF direction should lie. Interstellar Boundary Explorer (IBEX) subsequently discovered a ribbon, the center of which is conjectured to be the LISMF direction. The most recent He velocity measurements from IBEX and those from Ulysses yield a B–V plane with uncertainty limits that contain the centers of the IBEX ribbon at 0.7–2.7 keV. The possibility that Voyager 1 has moved into the outer heliosheath now suggests that Voyager 1's direct observations provide another independent determination of the LISMF. We show that LISMF direction measured by Voyager 1 is >40° off from the IBEX ribbon center and the B–V plane. Taking intomore » account the temporal gradient of the field direction measured by Voyager 1, we extrapolate to a field direction that passes directly through the IBEX ribbon center (0.7–2.7 keV) and the B–V plane, allowing us to triangulate the LISMF direction and estimate the gradient scale size of the magnetic field.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. University of New Hampshire, Durham, NH 03824 (United States)
  2. Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  3. Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  4. Southwest Research Institute, San Antonio, TX 78228 (United States)
Publication Date:
OSTI Identifier:
22518713
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 813; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATOMS; COSMIC RADIATION; COSMIC RAY PROPAGATION; GALAXIES; HELIOSPHERE; INTERSTELLAR MAGNETIC FIELDS; KEV RANGE; VOYAGER SPACE PROBES