Spectra DM for theoretical spectra?

[bonnarel]

>I am afraid the experts on theory spectra should be consulted before 
>concluding that all is in SDM + provenance.

Peter, I never claimed that. Have you seen that my little example rely on
SimDB ?


-----Message d'origine-----
De : Petr Skoda [mailto:skoda at sunstel.asu.cas.cz] 
Envoyé : jeudi 4 juin 2009 10:50
À : bonnarel
Cc : 'Alberto Micol'; dm at ivoa.net; theory at ivoa.net
Objet : RE: Spectra DM for theoretical spectra?

> Let's try something Carlos...
>  Give me the exact list of attributes you want to describe a theoretical
> spectrum and we try to build an extension to SSA with appropriate "utypes
> proposal" to describe them ...
> Cheers

I am afraid that thye EXACT list is not possible to define for EVERY model 
as e.g. my collegues have computed models corresponding to Kurucz with 
different geometry - spherical instead of plane-parallel. So the 
additional attribute is diameter of star in units of optical depths ...
You may have model with high Carbon abundance - it requires different 
physics. Yo may have non-LTE models which require densities of ions, 
electrons, electron temperature, if it is in movement (e.g. stellar winds) 
you have to add spped of the plassma, directions....

In more simplified way it may be just the limb darkening 
according different approximations .....

The theory of stellar atmospheres has been undergoing rapid progress as 
the speed of computers and GRIDs allow to do 3D magneto-hydro-dynamic 
simulations.

So just to build model of provenance for one particular usage 
(Carlos's-Kurucz code;-) is a bad way in terms of general goals of this 
effort .

It seems to be the much better approach must be taken - what is doing 
Frank La Petit is exactly example what it is needed - the result should be 
after all the spectrum to compare with observation of a nebula !

I agree with Carlos that the provenance model now cannot properly 
define Teff .... (to be honest - I do not see any 
space in characterization for theory spectra - the coverage, extend and 
resolution of axes etc is everything under my control - the grid in output 
code  - so it is all 
provenance - its the P.I intentions !!!!)


I am afraid the experts on theory spectra should be consulted before 
concluding that all is in SDM + provenance.

Petr Skoda

>
> Then I agree that for a theoretical spectrum a (Teff,logg,metallicity) set
> is closer to be provenance that to the be characterization.

> What I see equivalent to my idea of provenance is "these theoretical
> spectra were calculated using kurucz code, calculating a grid with this
> edges and this step for each axe, considering rotation or not, considering
> the presence of a disk or not, etc".
>
> I don't really see clearly yet if this makes a difference or not and maybe
> the provenance data model is the perfect place to consider these things.
>
> But, in Alberto's words, I don't see (teff,logg...) as the equivalent to
> instrument/telescope, but more the equivalent to data_axes (position,time)
> for observed spectra.

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