V392 Per in outburst

Information about outbursts of eruptive stars, Be activity, ...

Re: V392 Per in outburst

Postby etienne bertrand » Wed May 02, 2018 9:54 am

Bonjour Daniel,

Bravo pour le spectre, j'étais dans les même conditions que toi, ie, la toiture de mon voisin allait me cacher la Nova quelques minutes après avoir terminé la série, ouf. Coté météo c'était parfait, par contre ça ne l'est plus aujourd'hui... Nous avons capturé les mêmes photons de la Nova au même moment je penses lol. (avec le même spectro, les presque mêmes caméra,..).
Tu as raisons, c'est passionnant tout ce que l'on peut faire avec un spectro, c'est ce que je me disais hier soir en installant le matéreil : la plus part des gens pensent que le ciel est le même, statique chaque soir, alors que tout bouge et en ce moment une Nova ! C'est super de voir ces étoiles évoluer et penser que ce n'est pas une étoile mais une naine blanche et une étoile massive c'est super !

Merci François pour tes renseignements, ils permettent de bien comprendre le phénomène. Par contre qu'est ce que le FWHI ? C'est pas le FWHM ?
C'est une Nova He/N spectre type coronal ?

Bon ciel à tous.
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Re: V392 Per in outburst

Postby Robin Leadbeater » Wed May 02, 2018 11:07 am

I had only cloud and rain last night so I was glad to see your spectra this morning. Some gaps in the clouds are promised tonight. Hopefully they will come at the right time.

Francois, I will add my spectra to the BAA database and send you copies of the fits files for the ARAS list later today

Cheers
Robin
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Re: V392 Per in outburst

Postby Daniel Dejean » Wed May 02, 2018 11:29 am

Hello,
Lokking to the meateo map these last days I was suspecting Robin to send us all clouds from UK.... may not a true statement... :D
Hope you will have a good weather tonight.

Comming back to Etienne message. This m ygraphic interpretation of FWHI at 10% max as per François recommendation :

Image

Again, this evaluation is quick and durty, just to verify my understanding.
- continuum base level at 0.27
- max at 1.57
- height = 1.30
- 10% height = 0.13
- level for FWH measurement on graph : 0.27 + 0.13 = 0.4
- min Lambda at this level = -3400kms/s
- max lambda = 4000km/s
- total width = 7400km/s

If method is right we can go a more precise measurement.
Thank to François for his comment and changes to that over simplified trial.

Cheers,
Daniel
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Re: V392 Per in outburst

Postby Robin Leadbeater » Wed May 02, 2018 2:49 pm

Hi Daniel,

Dont forget that there will be a small correction to make for the resolution. (The line in the spectrum will be slightly wider than it actually is.) This can be approximated by

(true line FWHM)^2 ~ (measured line FWHM)^2 - resolution^2

So for example for an ALPY with a resolution of 13A (R=500 at H alpha) a measured FWHM of 30A will be a true FWHM of 30^2-13^2 = 27A, ~10% lower

Cheers
Robin

EDIT: OK I see the line is already much wider than this example so the correction is insignificant
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Re: V392 Per in outburst

Postby Francois Teyssier » Wed May 02, 2018 4:20 pm

Dear All,
The page is created: http://www.astrosurf.com/aras/Aras_DataBase/Novae/2018_NovaPer2018.htm
Thanks to all and Congratulations!

Daily evolution:
v392per.png


François Teyssier
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Re: V392 Per in outburst

Postby Francois Teyssier » Wed May 02, 2018 5:48 pm

J'ai demandé à Steve de nous écrire quelques mots sur le sujet (demain matin)
En tout état de cause, cela ne peut être la phase coronale (rarement observée dans les novæ), ni nébulaire
Il faut pour cela que l'éjecta s'étende et se dilue, si bien que sa densité (électronique) devient suffisamment faible pour que les raies "interdites" (excitées par collision), -notées entre crochets- puissent apparaître. Le résidu de l'enveloppe va se rétracter, ce qui augmentera sa température et créera ainsi un rayonnement suffisamment énergétique (UV, X et même gamma) pour ioniser les atomes de l’éjecta à des niveaux élevés.
Last edited by Francois Teyssier on Sat May 05, 2018 9:25 am, edited 1 time in total.
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Re: V392 Per in outburst

Postby etienne bertrand » Wed May 02, 2018 10:01 pm

Top, on va voir comment elle évolue. Vivement le papier de Steve et le bon temps pour vendredi peut être ?
On peut la suivre pendant un mois ? Quelle est la durée du phénomène ?
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Re: V392 Per in outburst

Postby Paolo Berardi » Wed May 02, 2018 10:09 pm

The ARAS group is always very active! Congratulations for your readiness and the excellent spectra. I was just able to observe it, during a brief clear sky moment between clouds and rain.

Lhires III and 1200 l/mm grating, very short total exposure for H-beta region. A little longer for H-alpha region.

Image

Image

The same line profiles (but heliocentric corrected) as a function of radial velocity.

Image

Image

From my observing site the nova will be visible not for long due to a building covering the north-west horizon. Very bad forecasts for the next days... It's a pity!

Paolo
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Re: V392 Per in outburst

Postby Robin Leadbeater » Wed May 02, 2018 10:26 pm

Nice line profiles Paolo ! Here is my ALPY spectrum from tonight, also showing the features developing in the line profiles.

v392per_20180502_861_Leadbeater.png
v392per_20180502_861_Leadbeater.png (18.11 KiB) Viewed 3641 times


The target is circumpolar from here at 55 North and I have a good north horizon so it may be possible to follow it for some time. Unfortunately it does not get completely dark in June/July though.

Robin
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Re: V392 Per in outburst

Postby Robin Leadbeater » Wed May 02, 2018 11:15 pm

Spectra plotted in absolute flux using V mag values from the AAVSO database. It is interesting to see how the peak flux at H alpha has remained constant as the continuum has fallen away

Robin

v392per_20180429_894_flux_Leadbeater.png
v392per_20180429_894_flux_Leadbeater.png (46.49 KiB) Viewed 3636 times
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