Nova in Cassiopea (nova Cas 2020)

Alerts and Monitoring of Novae

Re: Nova in Cassiopea (nova Cas 2020)

Postby Peter Somogyi » Fri Jul 31, 2020 12:30 pm

Last night's result with my 300/1200 Newton, 6 x 30 minute, Alpy 600 (18 micron slit), ATIK 414 EXm:
plot_novacas2020_20200730_833.png

The reddening is obvious.
I am wondering, what can be the emission at 4922A (used to be He I, but it has emission elsewhere).
Moreover, O I 7772 has prominent P-Cyg profile, though it's blended:
OI7772_novacas2020_20200730_833.png
OI7772_novacas2020_20200730_833.png (15.23 KiB) Viewed 1023 times

Peter
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Re: Nova in Cassiopea (nova Cas 2020)

Postby Francois Teyssier » Fri Jul 31, 2020 12:32 pm

Page opened: http://www.astrosurf.com/aras/Aras_DataBase/Novae/2020_NovaCas2020.htm


Nice to see OI 7772 so prominent, Peter!



François
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Re: Nova in Cassiopea (nova Cas 2020)

Postby Robin Leadbeater » Fri Jul 31, 2020 4:17 pm

The H beta and Fe curtain region (LHIRES 600/mm, R=1950)

novacas2020_20200731_078_Leadbeater.png
novacas2020_20200731_078_Leadbeater.png (30.16 KiB) Viewed 1003 times
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: Nova in Cassiopea (nova Cas 2020)

Postby Robin Leadbeater » Sat Aug 01, 2020 11:10 am

Peter Somogyi wrote:I am wondering, what can be the emission at 4922A


Hi Peter,

It appears in my spectrum too. The emission peak is at 4924A so could be Fe II 4923.92
There is also Fe II 5316.23 and visible faintly just in your spectrum I think, Fe II 5264.18

(Fe II Line identifications from Visual Spec)

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: Nova in Cassiopea (nova Cas 2020)

Postby etienne bertrand » Sat Aug 01, 2020 1:13 pm

Bonjour Christian,

Difficile ce problème, il n'y a vraiment pas de possibilité à faire un montage pour réussir à collecter l'info de la pollution lumineuse... la double bonnette pourrait résoudre cela ? Comment font les pros qui font des spectres très résolus depuis des observatoires avec pollution lumineuse ? Ils ont peut être 2 spectros cote à coté un pour le spectre l'autre pour la pollution lumineuse ?
Est ce que ça existerait des montages eshel maintenant qu'il y a des très grands capteurs CMOS qui pourraient utiliser une fibre en forme de fente au lieu d'etre un trou ? L'idée serait d'avoir le spectre et juste au dessus ou en dessous le fond de ciel sur quelques pixels pour pouvoir le soustraire ??
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Re: Nova in Cassiopea (nova Cas 2020)

Postby Peter Somogyi » Sat Aug 01, 2020 1:55 pm

Hi Robin,
Thank you for the line identification, so those all 4 peaks in your spectra then Fe II emissions then!
Last night I've made a repeat, same instrument and amount of exposure (6x30 minute) - except that got the star higher:
cmp_NovaCas_0730_vs_31.png
cmp_NovaCas_0730_vs_31.png (31.61 KiB) Viewed 956 times

There is a large Balmer EW decrement (similar including H-alpha) and O I 7772 emission, whilst the EW of all the "Fe II curtain" remained similar.
The continuum difference can be an error from my instrument (equatorial mount, off slit guiding sometimes).
Peter
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Re: Nova in Cassiopea (nova Cas 2020)

Postby Francois Teyssier » Sat Aug 01, 2020 4:28 pm

Peter,

I confirm: Fe II (42) multiplet always appears as 3 lines: 4924, 5018 and 5169
It is often the brightest multiplet

François

A list of lines identified in novae (adapted from Williams, 2012): http://www.astronomie-amateur.fr/Documents%20Novae/Raies_Novae.pdf
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Re: Nova in Cassiopea (nova Cas 2020)

Postby David Boyd » Sun Aug 02, 2020 9:48 am

Another spectrum of the nova recorded on 1st August under better conditions than my spectrum on 30th July.
As before LISA (23 micron slit) + C11 SCT + SXVR-H694 (unbinned).
The nova was slightly brighter at V = 12.81. Many Fe II lines now clearly visible.
Flux in H-alpha and H-beta has reduced to 2.7E-12 and 2.2E-13 erg/cm2/sec respectively.
P Cyg absorption still present on H-alpha extending blue-ward to -750 km/s.

David

novacas2020_20200801_919_D_Boyd.png
novacas2020_20200801_919_D_Boyd.png (52.41 KiB) Viewed 886 times
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Re: Nova in Cassiopea (nova Cas 2020)

Postby Peter Somogyi » Sun Aug 02, 2020 9:57 am

Nice Fe II crowd, David! - I've just started to report similar...
Here is my progress from last night, with same exposures as before (however, a windy weather):
cmp_NovaCas_0730_31_01.png
cmp_NovaCas_0730_31_01.png (67.56 KiB) Viewed 883 times

Balmer (and OI 7772) decrease should be because of the 0.5mag brightness increase from 07.30 to 07.31- despite of that, the EW of the Fe II multiplet seems to be increased.
Weather gone bad permanently, please continue!
Peter
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Re: Nova in Cassiopea (nova Cas 2020)

Postby David Boyd » Tue Aug 04, 2020 11:44 am

The nova has brightened steadily over the past 5 days reaching V = 12.07 on the night of 3rd August. The continuum level of the spectrum has correspondingly increased and there are now P Cyg absorption dips on most of the Fe II emission lines as well as on the H-alpha and H-beta lines. These typically extend to -600 km/s from the emission peak on the blue side. H-alpha and H-beta emission line fluxes have reduced to 2.3E-12 and 1.7E-13 erg/cms2/sec respectively.

David

_novacas2020_20200803_883_D_Boyd.png
_novacas2020_20200803_883_D_Boyd.png (91.74 KiB) Viewed 815 times
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