Bez tytulu slajdu

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Secondary population of neutral H in the inner
heliosphere seems deflected by 20o to the side
and 10o to the north
M.Bzowski(1), G.Gloeckler(2), V.Izmodenov(3),
S.Tarnopolski(1)
(1) Space Research Centre PAS (2) Department of
Atmospheric, Oceanic, and Space Sciences,
University of Michigan (3) Moscow State
University and Space Research Institute RAS
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Observations SWICS/Ulysses
H PUI distribution functions observed for a 1 yr
duration, when Ulysses travelled at ecliptic
latitudes shortly after solar min.
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Extraction of the H density gradient
With the gradient of PUI distribution function,
one can extract log-gradient of the seed neutral
population providing PUI production rate
homogeneous along r.
H PUI distribution function accumulated during
the 1 yr interval, then H gradient computed
from the gradient net density calculated
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Original simulations strategy
For ionization rate and radiation pressure, use
data from observations wherever possible.
In lack of actual data, use reasonable proxies
(no ad hoc fixes!)
Simulate H profiles along lines corresponding to
average monthly Ulysses positions on a fixed
distance mesh, compute resulting density profiles
as mean values. Calculate separately the primary
(interstellar) and secondary (Baranov Wall)
populations and co-add.
As boundary conditions at TS, take parameters
from Moscow MC model (including H and He) with
interstellar parameters from Witte 2004 (velocity
vector temperature) and Izmodenov et al. 2003
(proton and hydrogen density).
Do simulations using the Warsaw (SRC) 3D, kinetic
(test particle), time dependent model of neutral
H distribution in the inner heliosphere.
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Radiation pressure
Model fitted to Lyman-alpha time series obtained
from SOLAR 2000 v 1.24 (Tobiska et al. 2000).
Scaling coefficient for line center/line
integrated ratio applied, obtained from in-house
analysis.
In follow-on simulations, H density model with
radiation pressure dependent on atomic radial
velocity (Tarnopolski, Ph.D. thesis, in
preparation), based on solar full-disk Ly-alpha
profiles from Lemaire et al. (2002).
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Ionization rates
EUV ionization daily time series computed from
10.7 proxy, fitted.

• Ionization processes simulated
• H p charge exchange
• EUV ionization
• electron impact.

Electron impact less important, but with
non-vanishing consequences. Simulated as
stationary, spherically symmetric process, based
on averaged solar wind-electrons parameters
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Charge exchange
Ch-x daily values computed as nSW vSW ?(vSW),
with ? fm fit to Red Book data (Bzowski 2001)
In-ecliptic from solar wind parameters observed
in situ, collected in OMNI-2 data available on
the Web (there are caveats, though).
Latitude dependence from SWAN optical
observations of heliospheric Ly-alpha glow
(Bzowski et al., 2003)
helioltitude
shape factor
Model based on the formula
Rate at the poles (from Ulysses during solar min)

Heliolatitudes of north and south boundaries of
the slow wind (from SWAN polar holes)
Rate at the solar equator (from in-ecliptic
OMNI-2 data)
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Boundary conditions
Local Interstellar Cloud
nP 0.06 cm -3 nH 0.18 cm-3 nHe 0.015
cm-3 T 6400 K v 26.4 km/s
Primary population (original interstellar atoms)
n 0.03465 cm-3 v B -28.512 km/s T 6020 K
? B 254.68o ? B 5.31o
Secondary population (from charge exchange of
pristine interstellar gas with protons in the
Baranov Wall, mostly just in front of the
heliopause)
n 0.06021cm-3 vB -18.744 km/s T 16300 K
?B 254.68o ? B 5.31o
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First results both populations parallel
Density way too large, reduction of ionization
rate needed
Density reduced by changing the averaging of c-x
data, density still too high.
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Role of the two-populations approach
Red two populations, upwind directions as from
I/S He. Green one population, upwind parameters
as suggested by Lallement et al., Science
2005 no electron ionization in both cases.
Conclusion two-population simulations with He
parameters give slightly better (though not
satisfactory) results than single-populations
with i/s parameters deduced from spectral
Ly-alpha obs. Start fiddling with upwind
direction of the secondary population.
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Vary upwind direction of secondary population
!
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Room for further improvement radiation pressure
is function of vr
Early results classical hot model compared with
Doppler model
Doppler model predicts density deficit at
crosswind wrt classical model hence density
gradient will be higher. Work in progress
accommodate in the Doppler model 3D, time
dependent effects electron ionization.
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Conclusions
Good (though not perfect) fit of I/S H density
gradient deduced from Ulysses H PUI observations
obtained from simulations with the use of 3D,
time dependent 2 populations kinetic model, with
the secondary populations deflected by 20o to
the side and 10o to the north.
Boundary conditions, radiation pressure, and
ionization rates have grounds in observations.
However, non-standard treatment of data to yield
charge exchange rate had to be applied. Global
consequences for heliospheric hard to assess at
the moment.
Room to improve the agreement exists by
accommodating Doppler effect in radiation
pressure.