Heliosphere in the magnetized local interstellar medium: Results of a three-dimensional MHD simulation

1998 ◽  
Vol 103 (A2) ◽  
pp. 1889-1904 ◽  
Author(s):  
Timur J. Linde ◽  
Tamas I. Gombosi ◽  
Philip L. Roe ◽  
Kenneth G. Powell ◽  
Darren L. DeZeeuw
Keyword(s):  
Interstellar Medium ◽  
Three Dimensional ◽  
Local Interstellar Medium ◽  
Mhd Simulation

The Three‐dimensional Structure of the Warm Local Interstellar Medium. I. Methodology

2000 ◽  
Vol 528 (2) ◽  
pp. 756-766 ◽  
Author(s):  
Jeffrey L. Linsky ◽  
Seth Redfield ◽  
Brian E. Wood ◽  
Nikolai Piskunov
Keyword(s):  
Interstellar Medium ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Local Interstellar Medium ◽  
Three Dimensional Structure

scholarly journals Three-dimensional simulations of turbulent spectra in the local interstellar medium

2007 ◽  
Vol 14 (4) ◽  
pp. 351-359 ◽  
Author(s):  
D. Shaikh ◽  
G. P. Zank
Keyword(s):  
Interstellar Medium ◽  
Three Dimensional ◽  
Density Fluctuations ◽  
Spectral Energy ◽  
Local Interstellar Medium ◽  
Laboratory Plasmas ◽  
Self Consistent ◽  
Supersonic Plasma ◽  
Turbulent Spectra ◽  
Three Dimensional Simulations

Abstract. Three-dimensional time dependent numerical simulations of compressible magnetohydrodynamic fluids describing super-Alfvénic, supersonic and strongly magnetized space and laboratory plasmas show a nonlinear relaxation towards a state of near incompressibility. The latter is characterized essentially by a subsonic turbulent Mach number. This transition is mediated dynamically by disparate spectral energy dissipation rates in compressible magnetosonic and shear Alfvénic modes. Nonlinear cascades lead to super-Alfvénic turbulent motions decaying to a sub-Alfvénic regime that couples weakly with (magneto)acoustic cascades. Consequently, the supersonic plasma motion is transformed into highly subsonic motion and density fluctuations experience a passive convection. This model provides a self-consistent explaination of the ubiquitous nature of incompressible magnetoplasma fluctuations in the solar wind and the interstellar medium.

What lies immediately outside of the heliosphere in the very local interstellar medium (VLISM): morphology of the Local Interstellar Cloud, its hydrogen hole, Stromgren Shells, and 60Fe accretion

2020 ◽  
Author(s):  
Jeffrey Linsky
Keyword(s):  
Interstellar Medium ◽  
High Pressures ◽  
Three Dimensional ◽  
Neutral Hydrogen ◽  
Outer Edge ◽  
Interstellar Cloud ◽  
Local Interstellar Medium ◽  
Local Interstellar Cloud ◽  
H Ii Region ◽  
Partially Ionized

<p> We describe the very local interstellar medium (VLISM)<br>immediately outside of the outer heliosphere. The VLISM consists <br>of four partially ionized clouds - the Local Interstellar Cloud (LIC), <br>G cloud, Blue cloud, and Aql cloud that are in contact with the outer <br>heliosphere, and ionized gas produced by extreme-UV radiation <br>primarily from the star Epsilon CMa. We construct the <br>three-dimensional shape of the LIC based on interstellar line <br>absorption along 62 sightlines and show that in the direction of <br>Epsilon CMa, Beta CMa, and Sirius B the neutral hydrogen column <br>density from the center of the LIC looking outward is a minimum. <br>We call this region the ``hydrogen hole''. In this direction, the <br>presence of Blue cloud absorption and the absence of LIC absorption <br>can be simply explained by the Blue cloud lying just outside of the <br>heliosphere. We propose that the outer edge of the Blue cloud is a <br>Str\"omgren shell driven toward the heliosphere by high pressures in <br>the H II region. The outer edges of other clouds facing Epsilon CMa <br>are likely also Stromgren shells. Unlike previous models, the LIC<br>surrounds less than half of the heliosphere.</p><p>We find that the vectors of neutral and ionized helium flowing<br>through the heliosphere are inconsistent with the mean LIC flow <br>vector and describe several possible explanations. The ionization<br>of nearby intercloud gas is consistent with photo-ionization by <br>Epsilon CMa and hot white dwarfs without requiring additional <br>sources of ionization or million degree plasma. In the upwind <br>direction, the heliosphere is passing through an environment of <br>several LISM clouds, which may explain the recent influx of <br>interstellar grains containing 60Fe from supernova ejecta measured <br>in Antarctica snow. The Sun will leave the outer partof the LIC <br>in less than 1900 years, perhaps this year, to either enter the <br>partially ionized G cloud or a highly ionized intercloud layer. <br>The heliosphere will change in either scenario. An instrumented <br>deep space probe sending back in situ plasma and magnetic field <br>measurements from 500-1,000 AU is needed to understand the <br>heliosphere environment rather than integrated data along the <br>sightlines to stars.  </p>

Kinematical Structure of the Local Interstellar Medium: The Galactic Center Hemisphere

1997 ◽  
Vol 484 (2) ◽  
pp. 761-778 ◽  
Author(s):  
Ricardo Genova ◽  
John E. Beckman ◽  
Stuart Bowyer ◽  
Thomas Spicer
Keyword(s):  
Interstellar Medium ◽  
Galactic Center ◽  
Local Interstellar Medium

scholarly journals Abundances in the Gaseous Galactic Halo

1998 ◽  
Vol 11 (1) ◽  
pp. 86-89
Author(s):  
Ulysses J. Sofia
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
High Velocity ◽  
Galactic Halo ◽  
Solar Neighborhood ◽  
Local Interstellar Medium ◽  
The Galaxy ◽  
Metal Abundances ◽  
High Velocity Clouds

Abstract The well measured gas-phase abundances in the low halo suggest that this region of the Galaxy has total (gas plus dust) metal abundances which are close to those in the solar neighborhood. The gas-phase abundances in the halo are generally higher than those seen in the disk, however, this affect is likely due to the destruction of dust in the halo clouds. Observations of high velocity clouds (HVCs) in the halo suggest that these clouds have metal abundances which are substantially lower than those measured for the local interstellar medium. These determinations, however, are often of lower quality than those for the low halo because of uncertainties in the hydrogen abundances along the sightlines, in the incorporation of elements into dust, and in the partial ionization of the clouds.

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