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11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Morphology and ionization of the interstellar cloud surrounding the solar system
Science (New York, N.Y.)
|September 2, 1994
Summary
The sun encountered an interstellar cloud 2000-8000 years ago, skimming its surface. This interaction suggests the solar system developed a bow shock due to relative motion and cloud ionization.
Area of Science:
- * Heliophysics and space plasma physics.
- * Interstellar medium and solar system interactions.
Background:
- * The heliosphere is influenced by the surrounding interstellar medium.
- * Understanding the heliosphere's boundary is crucial for space weather prediction.
Purpose of the Study:
- * To determine the timing and nature of the sun's encounter with a local interstellar cloud.
- * To investigate the physical conditions and ionization state of the interstellar cloud.
- * To analyze the implications of the sun-cloud interaction on the heliosphere.
Main Methods:
- * Analysis of anomalous cosmic ray populations (specifically carbon) to derive electron density.
- * Examination of interstellar ratios of magnesium ions (Mg+/Mg°) towards Sirius.
- * Modeling of solar system and interstellar cloud relative motion and magnetic field orientation.
Main Results:
- * The sun's first encounter with the interstellar cloud occurred 2000 to 8000 years ago.
- * The sun is skimming the cloud's surface, with nearly perpendicular space motions.
- * Derived electron density of the cloud is 0.22 to 0.44 per cubic centimeter, supporting an equilibrium ionization model.
- * The upwind magnetic field is nearly parallel to the cloud surface.
- * Relative sun-cloud motion indicates the formation of a solar system bow shock.
Conclusions:
- * The heliosphere has recently interacted with a local interstellar cloud.
- * The ionization state of the cloud is consistent with equilibrium conditions.
- * The solar system likely possesses a bow shock due to this interaction.
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