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An update with Terry's spectrum which confirms and precises the fast change of the Balmer lines profiles
Spectra : Joan, Paolo, Terry, François
François

Hi,

In the _nova*.fit files, from my echelle, to standardize the intensities of the profile of the NEW SCT 2017, I took as a reference, from the first day, a graph of Umberto Sollecchia, "asdb_asassn-17hx_20170719_849.fit", ( Is in the database). In this way, I think that using a standard type, intensity variations are equivalent to each other. I use this system always for any star and with all my observations.

For this reason, the intensities of the previous graphs seem to vary if they compare to mine. (François, we should all agree).

According to the graphs that I present, it seems that the Hydrogen takes more strength, although the star is weakened in the visual.

The graphs "JGF" are observations with LINX, (Sta Maria), "J. Guarro" with MUSSOL, (Piera).

Friendly, Joan.

Joan,

- Could you explain the treatment with Umberto's spectrum?
- Yes, the emission of Balmer, almost null at maximum luminosity, strongly increase during the decline
(The photosphere receeds, its temperature increases, thus shift of the peak to UV and decrease of the visual luminosity at constant bolometric luminosity - this is the general behavior of the nova decline - the ionisation rate increases (followed by recombination and thus emission)
- The general appereance of the evolution of one line strongly depends of the wavelenght choosed for normalisation
- The best way to show the evolution should be to convert the spectra to flux using aavso database (and also Paolo's photometry)
- I think that the most important aspect of this wonderfull series is the profile of the lines (Balmer and Iron) and the fast change, now clearly established, between Paolo and Terry spectra
- The best way to study the evolution of the shape should be to normalize *also* the maximum intensity of the lines
- The ejecta remains optically thick and forbidden lines are still missing 2,4 mag under the maximum

All the best,

François

Bonjour François,

I totally agree with what you say.

I feel that I have not explained myself very well, what I want to say is that, in order to compare relative intensities, I would have to use the same pattern, in my case I decided to use a graph of the Umberto, (I agree Which is very random), but, at least, with my observations it gives a fairly reliable idea of the changes in relative intensity in hydrogen. This is also used for the intensity relative on the Iron lines.

As you say, we should have a pattern to normalize the graphs of all observers, (perhaps only relative intensities would be sufficient). The big question, what should be this pattern?

This work, must we do it, the observers? Or should prospective analysts do it?

Every day I observe the NEW, it is a real surprise.

Bien amicalement, Joan.

Hi Joan,

Here's a first attempt with flux calibrated spectra (using AAVSO V Band)
The emission increased strongly just at the begining of the optical decline, then the fux is almost stable until the fast change which occured between 2017-08-18.807 and 19.502

H alpha flux
Error ~ 5%

François

Merci beaucoup François,

C'est une bonne introduction. Nova Sct 2017, continue d'être actualité.

Amicalement, Joan.

Bonjour à tous, il profilo della nuova osservé le soir du 21/08/2017. Umberto

Hi to all, ( Buongiorno Umberto !! ),

Hydrogen has started a downward phase.

Cheers, Joan.

A spectrum obtained by a professionnal team on 22th with UVES
H beta line H alpha is saturated in their spectrum, thus they are very interested by the spectra in ARAS data base around this observation

Paolo detected (on Aug. 24) the decline of the emission detected in the red part of Halpha

Evolution with spectra obtained by Joan, Paolo and Terry normalisation of the continuum at ~ -1500 km/s

Note that the wings (> 500 km/s) are recovering the same shape than before the transcient emission detected on Aug 19.502

Congratulations for this excellent monitoring!

François

Bonsoir à tous, les profils de la nova observé le jour 25/08/2017 et 26-08-2017. Umberto