COROT / SEISMOLOGY
WORKING
GROUP
. . .
the actions
and responsibilities
The COROT/SWG is intended to prepare
and
run the optimal scientific interpretation of the COROT's observations
in the context of stellar seismology. This work is of course at the
base
of the mission profile determination and of the target selection.This
group
also has in charge to
- identify the weak points in the theoretical arsenal available to
interpret
the COROT's data,
- promote the investigation of these points and
- make possible an optimal interpretation as soon as possible.
We are presently in a phase dominated by the
priority of the selection of the specific targets for long runs (due to
early 2003, see the context...).
Among the actions achieved or under progress:
- Seismic interpretation (coord. G. Berthomieu OCA, Nice, bertho@obs-nice.fr): The
different techniques of seismic interpretation are evaluated in the
context
of the Corot programme. In the present stage, the different potential
targets
are compared in terms of their "seismic" interest.
- Optimization of the Seismo target selection in terms of
scientific
return (coord. G. Berthomieu OCA, Nice, bertho@obs-nice.fr):The
different potential targets are compared in terms of their
"seismic"
interest. This is done through Hare & Hounds exercise which
objective
is to confirm criteria of selection of the targets in the most
realistic
conditions. M.J. Goupil (LESIA), J. Provost (Dept. Cassini),
J.
Lochard (LESIA), G. Berthomieu (Dept. Cassini), I. Roxburgh (QMWC), E.
Michel (LESIA), A. Mazumdar (LESIA), P. Morel (Dept. Cassini), A. Noels
(IAGL),... (more
about this activity...)
- Seismic characterization of the target stars: (coord.
J. Provost, OCA, Nice, provost@obs-nice.fr):
A first phase of seismic analysis is often the characterisation of the
observed target according to classical seismic indexes (large and small
separation, delta nu_1, see Provost et al. Milestone
2000 Proc. ). This is seen as the way to find, within physical
assumptions, a close-enough model for further differential
studies. J. Provost (Dept. Cassini), M.J. Goupil
(LESIA), B. Popielski (LESIA/ CAC), G. Berthomieu (Dept. Cassini), I.
Roxburgh (QMWC), E. Michel (LESIA), A. Mazumdar (LESIA), P. Morel
(Dept. Cassini), A. Noels (IAGL), R. Ventura (OC), A. Bonanno
(OC), (more about this activity...)
- Binaries seismic interpretation (coord.. tbc, tbc):
Some of the potential targets are known binaries with stellar component
sometimes close in mass and thus in expected seismic characteristics.
The
scientific interest of such objects is strong, but the possibility to
distinguish
both oscillation spectra observed simultaneously is an open question.
Numerical
simulations have to be made in order to determine in which conditions
and
with which techniques this kind of target can be fruitfully analysed. tbc...
- Effect of moderate and fast rotation": (coord. M.J.
Goupil, LESIA,. Paris, Mariejo.Goupil@.obspm.fr):
Moderate and fast rotation induces important changes in the oscillation
frequencies of stars. To some extent, this can be treated with a
perturbative approach. Tools have been developed and their limits have
been precised. Beyond these limits, a 2D numerical modelling of the
oscillating star becomes necessary. The tools are presently
developed and the choice of the targets will have to be made
according to what we know of their domain of validity (see Goupil et
al. Milestone
2000 Proc.). M.J. Goupil (LESIA), J.C. Suarez (LESIA), W.
Dziembowski (CAC), F. Lignieres (OMP), M. Rieutord (OMP)
- Perturbative approach: (coord. M.J. Goupil, LESIA,
Paris, Mariejo.Goupil@.obspm.fr): M.J.
Goupil (LESIA), J.C. Suarez (LESIA),F. Perez (IAC),
- Non perturbative approach: (coord. M. Rieutord,
Obs.
Midi-Pyrenees,
Toulouse, France rieutord@ast.obs-mip.fr)
: M. Rieutord (OMP), F. Lignieres (OMP), ...
- Effect of fast rotation on the stellar structure and on
the
global
parameters determination:(coord. tbc, tbc)
: F. Perez Hernandez(IAC), A. Claret(IAA), E.
Michel(LESIA),
J.C. Suarez(LESIA/IAA), I. Roxburgh(QMWC)
- Transport of chemical species: (coord. S. Vauclair,
Obs. Midi-Pyrenees,
Toulouse, France <svcr@obs-mip.fr>:
The
transport of chemical species via diffusion, circulation or other
hydrodynamical
processes represents an important step to be considered in our
understnading
and modelling of stellar interiors It is important to estimate how
these
physical processes can affect the Corot observations and how, in
return,
the Corot observations can shed some new light on these processes. S.
Vauclair (OMP), J.-P. Zahn (LUTH), C. Charbonel (OMP), A. Thoul
(IAGL),....
- Excitation and amplitudes: (coord. I. Roxburgh,
Queen
Mary
and Westfield College, London, UK Ian.Roxburgh@obspm.fr)
: The estimation of the oscillation amplitudes and damping
rates
is of course of prime interest for Corot and for other space missions
(and
ground based search) because it is a dimensioning factor of any
instrument.
Ground-based observations tend to confirm the predictions within a
factor
2 or 3 which is in good agreement with the intrinsic error bars
attributed
to the estimation methods. Beyond this key aspect, it has been shown
(Samadi
et al. 2000) that the distribution of power with frequency could be
used
to discriminate between different treatements of the convective heat
transport.
The work on the amplitudes has to go in the perspective of determining
which specific targets or more likely set of targets would be the best
suited for this type of analysis. I. Roxburgh (QMWC), R. Samadi
(LESIA),
M.-J. Goupil (LESIA)
- Non adiabatic analysis: (coord. R. Scuflaire,
Institut
d'Astrophysique
et de Geophysique de Liege, Liege, Belgium R.Scuflaire@ulg.ac.be)
: The impact of non adiabatic effects present in the external
layers
of the stars on the pulsations has to be investigated and its influence
on e.g. mode instability estimated. R. Scuflaire (IAGL),
M.A. Dupret (IAGL), M.-J. Goupil (LESIA), R. Garrido (IAA), A. Noels
(IAGL),...
- Computation of stellar models : (coord. tbc tbc)
: Several numerical tools are being used for stellar modelling
in the preparation of the work of seismic analysis. Their results have
to be compared in order to optimize the expected diagnostics. P.
Morel(OCA),
Y. Lebreton (GEPI), A. Noels (IAGL), ...
- Data analysis (coord. T. Appourchaux,ESTEC , Noordwijk thierrya@so.ESTEC.ESA.NL)
: The data analysis techniques are developed and tested within the
framework
of Hare & Hounds exercises intended to provide as realistic
conditions
as possible. T. Appourchaux (SSD), T. Toutain (Dept. Cassini), C.
Barban
(LESIA), P. Boumier (IAS), F. Baudin (IAS), R. Garcia (SAP), M. Bossi
(OAM)
(more
about this activity...)
- Solar-like oscillations data analysis: (coord. T.
Appourchaux, ESTEC,
Noordwijk, thierrya@so.ESTEC.ESA.NL)
: The methods developed in the framework of helioseismology have to be
tested, adapted and completed for the stellar case. This work is
in progress in the framework of Hare and Hounds exercises (more about
this
activity...)T. Appourchaux (SSD), T. Toutain (Dept. Cassini), C.
Barban
(LESIA), P. Boumier (IAS), F. Baudin (IAS), R. Garcia (SAP), M. Bossi
(OAM),
A. Noels (IAGL), A. Thoul (IAGL), B. Vatovez (IAGL),... (more
about this activity...)
- delta Scuti and related objects data analysis: (coord.
E.
Michel,
LESIA, Paris, Eric.Michel@obspm.fr): The
methods developed in the framework of ground-based coordinated networks
have to be tested, adapted and completed for the Corot data
specificities. E.
Michel (LESIA), M. Bossi (OAM), T. Arentof (IVS), ...
- Time - frequency analysis: (coord. F. Baudin, IAS,
Orsay,
France, Frederic.Baudin@ias.fr): The
Corot long runs (150 days) will give a unique acces to the
oscillation
behavior on time scales of a month to 5 month. This cannot be done from
the ground. The time - frequency analysis of these time series has to
be
prepared.
- Image analysis: (coord. F. Baudin, IAS, France, Frederic.Baudin@ias.fr):
For some of the the target stars, it will be possible to download
images
in addition to the photometry produced onboard. These images will be
used
to overcome specific parasite or pointing problems and to obtain
general
informations on the evolution of the instrumental photometric
performances.
The techniques to be used for the analysis of these images are beeing
developed
and tested. F. Baudin (IAS), R. Samadi (LESIA), M. Auvergne
(LESIA),
E. Michel (LESIA)
- Delta Scuti targets characterization: (coord. E. Poretti,
OAM, Italy, poretti@merate.mi.astro.it ):
The part of the Corot Program dedicated to delta Scuti objects requires
a large search for potential candidates and dedicated ground
based observations to confirm variability characteristics. E.
Poretti (OAM), C. Aerts (IVS), R. Garrido (IAA), G. Handler (IA), M.J.
Goupil (LESIA), J.A. Belmonte (IAC), E. Michel (LESIA), J.C. Suarez
(LESIA), P. Mathias (Dept. Cassini),... (more
about this activity..get
document.)
- An open cluster for Corot: (coord. J.C. Suarez
LESIA/IAA,
France/Spain, JuanCarlos.Suarez@obspm.fr):
The
interest for open cluster is strong in seismology, because of the
additional
constraints brought by the classical hypothesis of similar age,
chemical
composition, distance one can make for the different objects
considered.
While we hardly can find in the Corot accessible field of view, a
cluster
for which solar-like oscillations can be studied in reasonable
signal-to-noise
ratios, we consider the possibility to observe an open cluster within
which
several delta Scuti and other classical pulsators hopefully might be
observed
in good conditions.J.C. Suarez (LESIA,IAA), E. Michel (LESIA), S.
Martin
Ruiz (OAM),...
Once candidates for Primary targets are known for
long run, a choice still remains to be done between the different
Primary
candidates and the candidate Secondary targets associated with them. In
this respect, it is important to identify the classical pulsators in
the
vicinity of candidate Primary targets.
- Beta Cephei and SpB targets: (coord. C. Aerts, Katholieke
Universiteit
Leuven, Instituut voor Sterrenkunde,Leuven, Belgium Conny@ster.kuleuven.ac.be):
These classical pulsators do belong to the class of "specific
plusators"
which are known to present oscillations and will be considered in the
selection
of the Corot fields of observations. One open action is thus to
characterize
the objects beloning to this class which could be included in the Corot
fields for a long run.E. C. Aerts (IUVS),
- Be targets: (coord. A.M. Hubert, GEPI, Paris,
France Anne-Marie.Hubert@obspm.fr):
These classical pulsators do belong to the class of "specific
plusators"
which are known to present oscillations and will be considered in the
selection
of the Corot fields of observations. One open action is thus to
characterize
the objects beloning to this class which could be included in the Corot
fields for a long run.A.M. Hubert (GEPI), M. Floquet (GEPI), E.
Janot-Pacheco
(Brazil). C. Aerts (IUVS),
- Gamma Dor. targets: (coord. G. Handler, Univ. of Vienna,
Wien, Austria gerald@saao.ac.za):
These classical pulsators do belong to the class of "specific
plusators"
which are known to present oscillations and will be considered in the
selection
of the Corot fields of observations. One open action is thus to
characterize
the objects beloning to this class which could be included in the Corot
fields for a long run.W.W. Weiss (IA),
- Lambda Boo and ro Ap targets: (coord. W.W. Weiss,
Univ.
of
Vienna, Wien, Austria weiss@isaac.astro.univie.ac.at):
These classical pulsators do belong to the class of "specific
plusators"
which are known to present oscillations and will be considered in the
selection
of the Corot fields of observations. One open action is thus to
characterize
the objects beloning to this class which could be included in the Corot
fields for a long run.W.W. Weiss (IA), G. Handler (IA),