THE INTERACTION OF THE INTERSTELLAR MEDIUM WITH THE SUN: THE NEWEST FRONTIER THE SCIENCE BEHIND THE

1
THE INTERACTION OF THE INTERSTELLAR MEDIUM WITH
THE SUN THE NEWEST FRONTIER- THE SCIENCE BEHIND
THE INTERSTELLAR MISSION GARY P.
ZANKINSTITUTE OF GEOPHYSICS AND PLANETARY
PHYSICS (IGPP)UNIVERSITY OF CALIFORNIA, RIVERSIDE
2
(No Transcript)
3
(No Transcript)
4
Overview of Scale
5
Life Cycle of Interstellar Atoms
6
Neutral Interstellar Atoms Basic Interaction

• Charge exchange interaction of interstellar atoms
  and protons and then sometimes charge exchange
  interaction of pickup ion with neutral hydrogen
• A H ? H A
• H A ? H A

H
H
A
H
Pickup ion
A
A
H
7
Three Distinct Neutral Populations
plasma temperature
REGION 1
REGION 2
REGION 3
8
Plasma Velocity Bulk vs Thermal

Inner Heliosheath
Outer He- liosheath
LISM
Ubulkltltvtherm
Ubulk gt vtherm
Ubulk gt vtherm
Sun
Region 3 ubulkgtgtvtherm
TS
BS(?)
HP
Region 2
Region 1A
Region 1B
9
Charge Exchange Interaction

Inner Heliosheath
Outer Heliosheath
LISM
H3
HPI
H1
HLISM
HACR
HPI
H2
HPI
HPI
HLISM
HPI
HLISM
HSW
Sun
Region 3
HLISM
TS
BS
HP
H3
Region 2
Region 1A
Region 1B
10
Effect of charge exchange.
11
Large-Scale Solar Wind
Local interstellar medium partially ionized.
HOME
12
Heliospheric Structure
2-shock model
1-shock model
13
Interstellar Neutral Atoms and the Structure of
the Heliosphere
14
Life Cycle of Interstellar Atoms
15
Shock Acceleration of Anomalous Cosmic Rays
16
Modulation of Anomalous Cosmic Rays
17
Solar Minimum and Maximum
18
The Dynamical Heliosphere
19
(No Transcript)
20
(No Transcript)
21
Simulations
3.
1.
2.
1. Quasi-equilibrium state 2. Instability
triggered by perturbations from previous cycle 3.
Instability develops. Mushroom-shape structures
are a signature of R-T 4, 5 Structure is
advected along the heliopause. Relaxation
phase. 6. Return to the quasi-equilibrium 1
cycle 100 years TS oscillates with an
amplitude of 3 AU
4.
5.
6.
22
2-Fluid simulation
23
IBEXThe Interstellar Boundary ExplorerThe
Future
24
www.ibex.swri.edu
25
Global ENA Images Questions I III
Global ENA images easily differentiate types of
TS interactions Differentiate differences
Upstream / Downstream Dawn /Dusk North
South Subtle asymmetries in global images
illuminate flow patterns beyond the termination
shock
Extremes of differential ENA fluxes from 0.3-0.6
keV predicted for a strong gas-dynamical TS (top)
and a TS weakened by a large pickup ion pressure
(bottom) Gruntman et al., 2001.
26
Global Energy Spectra Questions I, II III
ENA energy spectra provide direct measures of
ions beyond TS solar wind pickup
protons energetic protons Spectra as a function
of direction provide show 3D configuration of the
shock and energy partition of the ions at the
shock Spectra also provide information about
how EP pressure modifies the TS and what types of
injection processes may be at work there
8 E Bands
6 E Bands
Predicted ENA distributions near HSp nose for
strong (black) and weak (green) TS Gruntman et
al., 2001. ENAs gt1 keV are accelerated inner
heliosheath protons based on projecting observed
distributions beyond TS.
27
Wider Implications
Absorption while traversing the ISM
Absorption due to neutral H in the heliosphere
Sun
Star
28
Other Solar Winds and Related Physics
Prediction of an enormous wall of neutral
hydrogen in front of the heliosphere. The
verification of this prediction was not expected
for 20 years or more. An example of scientific
serendipity the accidental discovery of the
hydrogen wall!
Observations towards alpha Cen and Proxima Cen
with superimposed theoretical models.
Observations of Lyman-alpha absorption by six
different stars with a theoretical model
superimposed on the data.
Modeling the ? Cen AB / Proxima Cen System

• Understanding the Sun and LISM interaction led
  directly to new discoveries about other stars
• The discovery of a hydrogen wall about another
  star (alpha Cen)
• The discovery of a stellar wind from a G class
  star (alpha Cen).

Sketch of ? Cen/Proxima Cen configuration