Herschel et ALMA

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Herschel et ALMA
Spectre de ro-vibration HAPs chaînes carbonées
GHz
1500
2000
500
1000
mm
170
400
240
1200
20
60
40
cm-1
Herschel HIFI très haute résolution jusquà
107 (134 kHz à 1,5 THz)
ALMA
hydrocarbures aromatiques polycycliques
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Contraindre les physico-chimie des proto-étoiles
à partir de raies

• Les enveloppes proto-stellaires émettent des
  raies, principalement dans le domaine
  millimétrique à infrarouge
• Transitions millimétriques CO, H2CO, CH3OH
• Transitions FIR CO, H2O, C, O
• Lintensité des raies dépend de la température et
  de la densité et des abondances moléculaires
• Des raies avec des énergies suffisantes (100 K)
  permettent de sonder les parties internes des
  proto-étoiles dans lesquelles ces raies sont
  excités

n,T
E1 gt E2
log R
E2
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Proposed spectral analysis scheme (in order)

• Simulation of spectra to prepare measurement
  campaigns
• (spectral surveys) Identification of as many
  species present as possible.
• Species by species characterization
• For the species where it is possible LVG model
  or equivalent (e.g RADEX) determination of the
  best parameters by c2 minimisation.
• If LVG not possible or ETL more appropriate ETL
  model. Determination of best parameters using a
  rotational diagram.

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CASSIS -Present state of the program - LTE model
Tools Baseline gaussian fit Rotational diagram
JPL
Observed spectrum
CDMS
compare line-by-line or globally
automatic periodic update
Vary parameters
Recalculate intensities - LTE model
Single spectroscopic database
Simulated Spectrum
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Predict overview spectra
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Select molecules and enter parameters
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Fit and subtract a baseline
skip rapidly from one line to the next
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Fit a gaussian and compare with predictions from
the model
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Show close lying components
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Interactive creation of rotational diagrams
Choose different areas
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Compare multi-species simulations with observed
spectra
Choose different areas
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Comet model
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Future Developments - done, next step, later?
Template (initial source parameters)
Statistical tools
rotational diagram
ANALYSIS
TOOLS
MODELS
Line-by-line global display
AI
Collisional databases

MODELS
LVG
comets
absorption
LTE
other
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CASSIS - Development principles

• Specific features of HIFI/HSO
• Lots of data in a short time
• Very large spectral range (high spectral
  resolution)
• Rapid first analysis needed to define subsequent
  observations
• ESA wants a standard environment for data
  analysis before launch.
• Other instruments
• Versatility to work on data from other
  high-spectral-resolution instruments.
• A few transitions ? large spectral scans

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CASSIS development principles

• A first spectral analysis should give rapidly a
  first overview of physical and chemical
  properties of the studied object
• Start with simple models
• Access to databases.
• As exhaustive as possible.
• The user should not have to worry about
  converting inhomogeneous units or working out
  different formats.
• Give access to the latest data
• Respect the intellectual property of database
  managers and the authors of models.
• The task of verifying data and models needs to be
  shared according to everyones personal
  competences.

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How CASSIS can help to get the most out of models
and data already available.

• Controlling what is going on
• Faster interactive analysis the scientist can
  verify the results at each stage
• Visual display
• Modularity et homogeneity
• Separation of data and models. Free choice of
  data for each model.
• Make available the most recent data
• Compare the results of different models in a
  standard environment.
• Associate different analysis tools without
  worrying about input and output formats.

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How CASSIS can help to get the most out of models
and data already available.

• Open project
• Available to all qualified scientists
• Few conditions on the user.
• Contents well documented and verifiable.
• User feedback
• Knowledge sharing

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CASSIS choice of programming language

• Simple to use
• The computer tools must work in as many computer
  environments as possible (PC, Mac, workstations,
  windows, Linux,).
• Easy updating
• Compatible with Herschel Space Observatory
  computer toolboxes
• Compatibles with VO toolboxes
• Input/output VO compatible.
• VO protocols (astrogrid etc.)
• JAVA

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Proposed spectral analysis scheme (in order)

• Simulation of the spectrum for all identified
  species slight change in parameters where
  necessary
• Offsets observed in the spectrum. Problems with
  the theory or the data ? feedback
• Treat with more sophisticated models. Within or
  outside the CASSIS project ? For inclusion in
  CASSIS
• The model must compute spectra rapidly
• Or use a table of pre-calculated