P1254503521UCxFl - PowerPoint PPT Presentation

Title: P1254503521UCxFl


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Journée vent solaire (21 juin 2005) J.-C.
Vial Merci à L. Dolla, A. Gabriel, E. Marsch,
N. Raouafi, S. Koutchmy pour leurs
contributions (quelquefois non sollicitées) !
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• Raouafi

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UVCS Results
Very broad line profiles emitted by heavy ions (O
VI, Mg X) in the polar coronal holes
Raouafi
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Temperature profiles in the corona and fast solar
wind
SP
SO
( Si 7)
Ti mi/mp Tp
( He 2)
Corona
Solar wind
Cranmer et al., Ap.J., 2000 Marsch, 1991

• Marsch

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Interpretation of UVCS observations
Wave-particle energy exchange at cyclotron
frequencies of the solar wind species
High anisotropies in the velocity
distributions of the scattering atoms
Raouafi
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Heating and acceleration of ions by cyclotron and
Landau resonance
Doppler broadening Thermal speed
Temperature
T(2-6) MK r 1.15 RS
? ? Z/A
Tu et al., Space Sci. Rev., 87, 331, 1999
Ion heating ? mass/charge

• Marsch

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Area of interest polar coronal holes
Modèle Banazskiewicz et al. 1998 Raouafi
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O VI Total Intensities
The observed intensities are reasonably
reproduced by most of the density models (DKL,
GH94, Cra99) Guh99 Ess99 give relatively low
intensities at low altitudes
(Raouafi Solanki, 2004b)
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O VI Widths Intensity Ratios

• The LOS-integrated profiles are very sensitive
  to the density stratification details
• Tpar Tperp ???
• The calculated intensity
• ratios are relatively close to
• the observed ones
• (except for Guh99 Ess99)

(Raouafi Solanki, 2004a,b)
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Sample Solutions for Several Minor Ions
Ions with smaller Q are strongly heated and
accelerated closer to the Sun due to their lower
gyro-frequencies. Differences in temperature and
velocity become smaller from distances larger
than around 1.5 Rs. Do ionization balance
calculations need to take into account the
different flow speeds for different ionization
stages of the same element ? Patsourakos et al.
(ISSI 2001)
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Effective temperatures model versus
observations
At both distances, a rather good agreement
(within a factor less than 2 for all the studied
cases but one) between the observations and the
model can be seen. The discrepancy concerning
Fe XII at 1.18 Rs may result from poor
signal-to-noise ratio. Patsourakos et al. (ISSI
2001)
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Inferences for elemental abundances
Fe/O in the inner corona
Both oxygen and iron are depleted with respect to
hydrogen from the distances where they start
flowing faster than the protons. However, their
different gyro-frequencies lead to an
over-abundant oxygen in the inner corona (1-1.3
Rs ) with respect to iron (inverse FIP-effect ?).
The abundances reach again their initial values
further away, where all species flow at around
the same speed. Patsourakos et al. (ISSI 2001)
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Figure 1- Variations radiales de la vitesse de
macro-turbulence dans la couronne pour
différentes régions mesurées daprès le profil
détaillé de la raie verte du Fe XIV. Chaque
mesure indiquée sur ce graphe est le résultat
dune moyenne effectuée sur un grand nombre de
mesures et les barres correspondantes indiquent
la vraie dispersion (dorigine coronale) sur les
mesures ponctuelles effectuées à distance radiale
constante. Lamplitude de ces barres montre
aussi, approximativement, la valeur des décalages
Doppler nets mesurés sur la position instantanée
du centre de gravité de la raie. Les erreurs de
mesures individuelles des profils de la raie sont
très inférieures à ce qui est montré par les
barres. A noter que les mesures au Nord indiquent
une rapide croissance près du trou coronal
polaire. Même au Sud, les vitesses sont
supérieures à celles qui sont mesurées près de
léquateur. Contesse, Koutchmy, Viladrich,
2004
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Dolla
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Méthode pour contraindre x
Observations v² 2kT/m x² en fonction de
laltitude même pente pour plusieurs ions entre
60 et ?80 arcsec ? soutient
lhyp. que seul x est responsable de la variation
de la largeur sur cet intervalle, pour les ions
de plus grand q/m, dont Mg X Dolla
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Méthode pour contraindre x
Dolla
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Dolla
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Dolla
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Différence de température entre 60 et 100 au
dessus du trou polaire Nord, mai 2002(en tenant
compte de la variation de x )
? Chauffage préférentiel en fonction de q/m
Dolla
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On the source regions of the fast solar wind in
coronal holes
Insert SUMER Ne VIII 770 Å at 630 000
K Chromospheric network Doppler shifts Red
down Blue up Outflow at lanes and junctions
Image EIT Corona in Fe XII 195 Å at 1.5 M K
Hassler et al., Science 283, 811-813, 1999
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Outflow speed in interplume region at the coronal
base
1.05 RS EIT FeIX/X Eclipse 26/02 1998
1833 UT
SUMER
67 km/s
O VI 1031.9 Å / 1037.2 Å line ratio Doppler
dimming
Patsourakos and Vial, AA, 359, L1, 2000
Te Ti 0.9 M K, ne 1.8 107 cm-3
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Outflow velocity at the onset of the fast solar
wind   From work by Gabriel, Bely-Dubau, Abbo and
others
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This curve is a bi-product of a study of wind
velocities observed in Doppler dimming by SUMER
and UVCS. Without believing all of our project
results, this curve cannot be much in error. It
is consistent with observed radial density
profiles, well-established super-radial
expansion profiles and solar wind flux at 1 AU,
on the assumption of conservation of radial flow
of mass. The particular shape below 2 Ro is
due to the non-radial expansion profile of the
magnetic field. (Munro and Jackson). This is
valid for a simple solar minimum configuration
and starts at a polar coronal hole.By 4 Ro, it
fills most of the 4 pi solid angle From work by
Gabriel, Bely-Dubau, Abbo and others
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