Properties of the Local Galactic Medium

As the Sun moves through the local galactic medium, its supersonic, ionized solar wind carves out a cavity called the heliosphere. Recent observations from the Interstellar Boundary Explorer (IBEX) spacecraft show that the motion of the Sun relative to the surrounding medium is slower and in a somewhat different direction than previously thought. Further, the observations of IBEX have been used to probe the Neon to Oxygen abundance in the local galactic medium, which has major implications for the entrainment of volatile elements within the dust embedded in the surrounding medium. Combined consensus values for the new velocity vector of the heliosphere through the local galactic medium have important ramifications for its global interaction with our heliosphere, which cocoons and protects our entire solar system. Further, these new values show that our position in the galaxy is solidly within an entity that is known to astronomers as the local interstellar cloud. These studies by IBEX provide critical information concerning the heliosphere’s domain within the galaxy. For example, these new and unexpected results from IBEX show that the interaction between the heliosphere and local galactic medium is sufficiently slow that no bow shock should form ahead of the heliosphere as had been widely expected for decades. These advances are critical for discovering how our home within the galaxy changes with time, thereby establishing the history and future of Earth’s space environment.

References:

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Hlond, M., M. Bzowski, E. Möbius, H. Kucharek, D. Heirtzler, N.A. Schwadron, M.E. O’Neill, G. Clark, G.B. Crew, S. Fuselier, and D.J. McComas, Precision pointing of IBEX–Lo observations, ApJ Supplement Series, 198:9, doi:10.1088/0067-0049/198/2/9, 2012.

Lee, M.A., H. Kucharek, E. Möbius, X. Wu, M. Bzowski, and D. McComas, An analytical model of interstellar gas in the heliosphere tailored to IBEX observations, ApJ Supplement Series, 198:10, doi:10.1088/0067-0049/198/2/10, 2012.

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Bzowski, M., M.A. Kubiak, E. Möbius, P. Bochsler, T. Leonard, D. Heirtzler, H. Kucharek, J.M. Sokol, M. Hlond, G.B. Crew, N.A. Schwadron, S.A. Fuselier, and D.J. McComas, Neutral interstellar helium parameters based on IBEX–Lo observations and test particle calculations, ApJ Supplement Series, 198:12, doi:10.1088/0067-0049/198/2/12, 2012.

Bochsler, P., L. Petersen, E. Möbius, N.A. Schwadron, P. Wurz, J.A. Scheer, S.A. Fuselier, D.J. McComas, M. Bzowski, and P.C. Frisch, Estimation of the neon/oxygen abundance ratio at the heliospheric termination shock and in the local interstellar medium from IBEX observations, ApJ Supplement Series, 198:13, doi:10.1088/0067–0049/198/2/13, 2012.

Saul, L., P. Wurz, D. Rodriguez, J. Scheer, E. Möbius, N. Schwadron, H. Kucharek, T. Leonard, M. Bzowski, S. Fuselier, G. Crew, and D. McComas, Local interstellar neutral hydrogen sampled in–situ by IBEX, ApJ Supplement Series, 198:14, doi:10.1088/0067–0049/198/2/14, 2012.