Nova in Cassiopea (nova Cas 2020)

Alerts and Monitoring of Novae

Re: Nova in Cassiopea (nova Cas 2020)

Postby Christophe Boussin » Wed Aug 05, 2020 6:22 pm

Hello all,

I obtained the following spectrum of nova Cas 2020 the 5th of August at 00 h 02 TU with my Alpy 600 (resolution of 506, JJ = 2459066.5013) and an acquisition time of 70 min :

_novacas2020_20200805_001_Christophe Boussin_3750_7565.png
Nova Cas 2020 on August 5th, 2020
_novacas2020_20200805_001_Christophe Boussin_3750_7565.png (92.05 KiB) Viewed 1034 times


novacas2020_20200805_001_Christophe Boussin.png
Nova Cas 2020 on August 5th, 2020 (identification of lines from PlotSpectra)


novacas2020_20200805_001_Christophe Boussin_zoom.png
Nova Cas 2020 on August 5th, 2020 (zoom)


As David, I noticed also P Cyg absorption profiles on the Halpha and Hbeta lines and on some Fe II emission lines.

Clear skies,

Christophe BOUSSIN
CBO (Newton 200 F/5 / Alpy600 / Atik 314L+ / Atik Titan) @ ARAS database
Christophe Boussin
 
Posts: 84
Joined: Sun Aug 21, 2016 6:04 pm

Re: Nova in Cassiopea (nova Cas 2020)

Postby Christian Buil » Thu Aug 06, 2020 4:41 pm

High resolution spectrum for the 4.9 August 2020 (eShel, Newton 250, ASI6200MM). Large P-Cyg profile at Halpha level:

Image

Detail of Hbeta and Fe II lines:

Image

and the sodium doublet profile (the continuum is dominated by sodium light pollution):

Image

Christian Buil
Christian Buil
 
Posts: 1356
Joined: Mon Sep 26, 2011 6:59 pm

Re: Nova in Cassiopea (nova Cas 2020)

Postby Christophe Boussin » Thu Aug 06, 2020 6:58 pm

Hello all,

Here is my update for the nova Cas 2020 with the following spectrum obtained the 6th of August at 00 h 32 TU with my Alpy 600 (resolution of 507, JJ = 2459067.5225) and an acquisition time of 75 min :

_novacas2020_20200806_022_Christophe Boussin_3750_7565.png
Nova Cas 2020 on August 6th, 2020
_novacas2020_20200806_022_Christophe Boussin_3750_7565.png (89.85 KiB) Viewed 976 times


novacas2020_20200806_022_Christophe Boussin.png
Nova Cas 2020 on August 5th and 6th, 2020 (identification of lines from PlotSpectra)


novacas2020_20200806_022_Christophe Boussin_zoom.png
Nova Cas 2020 on August 5th and 6th, 2020 (zoom)


Clear skies,

Christophe BOUSSIN
CBO (Newton 200 F/5 / Alpy600 / Atik 314L+ / Atik Titan) @ ARAS database
Christophe Boussin
 
Posts: 84
Joined: Sun Aug 21, 2016 6:04 pm

Re: Nova in Cassiopea (nova Cas 2020)

Postby David Boyd » Fri Aug 07, 2020 11:31 am

The nova now appears to be approaching its maximum brightness with V = 11.56. Fe II lines are still present while the flux in H-alpha and H-beta has decreased to 1.9E-12 and 1.5E-13 erg/cm2/sec respectively. P Cyg absorption is still present on H-alpha and Fe II lines extending to -600 km/s.

David

novacas2020_20200806_886_D_Boyd.png
novacas2020_20200806_886_D_Boyd.png (89.25 KiB) Viewed 933 times
David Boyd
 
Posts: 123
Joined: Wed Dec 11, 2013 5:50 pm

Re: Nova in Cassiopea (nova Cas 2020)

Postby Peter Somogyi » Sat Aug 08, 2020 10:30 am

At same night as David, R~2000, cloudy sky (could save only 1 x 30 min), 300 x 1200 Newton + APM Barlow 2.67 + LHires III + 600/mm grating + 35 micron slit + ATIK 428 EXm:
novacas2020_20200806_941.png
novacas2020_20200806_941.png (58.09 KiB) Viewed 891 times

Very similar Fe II features to the eShel shown by Christian 1 day before (08.05), except that I have no pollution in this region at all.
Minor double absorption present above noise (4763A, 5041A, 5367A +/- 7A) but I can't determine their origin.
Peter
Peter Somogyi
 
Posts: 401
Joined: Sun Jul 13, 2014 8:56 am

Re: Nova in Cassiopea (nova Cas 2020)

Postby Peter Somogyi » Sun Aug 09, 2020 7:55 pm

Inserting an orange wratten filter, experimented in two IR regions with the 600/mm (visual) grating.
First taken the O I 7773 region (7450-8160A):
novacas2020_20200808_826.png
novacas2020_20200808_826.png (19.35 KiB) Viewed 856 times

Next, captured the region with O I 8446:
novacas2020_20200808_914.png

The strong Paschen end contaminated all the O I 8446 and Ca II triplet P-Cyg profile (I'd expect the Paschen serie even stronger at larger wavelengths).
After then, revisited the H-beta / Fe II region - this time with 3x30 min exposures:
novacas2020_20200809_024.png

Comparing to previous, no change in 2 days above noise. Unidentified absorptions visible.
Weather gone bad again.
Peter
Peter Somogyi
 
Posts: 401
Joined: Sun Jul 13, 2014 8:56 am

Re: Nova in Cassiopea (nova Cas 2020)

Postby Christophe Boussin » Wed Aug 12, 2020 12:01 am

Hello all,

Here is my new update for the nova Cas 2020 with the following spectrum obtained the 7th of August at 00 h 03 TU with my Alpy 600 (resolution of 507, JJ = 2459068.5023) and an acquisition time of 75 min :

_novacas2020_20200807_002_Christophe Boussin_3750_7565.png
Nova Cas 2020 on August 7th, 2020
_novacas2020_20200807_002_Christophe Boussin_3750_7565.png (95.02 KiB) Viewed 798 times


novacas2020_20200807_002_Christophe Boussin.png
Nova Cas 2020 on August 5th, 6th and 7th, 2020 (identification of lines from PlotSpectra)


novacas2020_20200807_002_Christophe Boussin_zoom.png
Nova Cas 2020 on August 5th, 6th and 7th, 2020 (zoom)

Between August 5 and 7, I didn't notice any significant changes in the spectra.
And in the last days, unfortunately, the weather has become too uncertain to continue my observations.

Clear skies to all,

Christophe BOUSSIN
CBO (Newton 200 F/5 / Alpy600 / Atik 314L+ / Atik Titan) @ ARAS database
Christophe Boussin
 
Posts: 84
Joined: Sun Aug 21, 2016 6:04 pm

Re: Nova in Cassiopea (nova Cas 2020)

Postby Dubreuil Pierre » Wed Aug 12, 2020 6:58 am

Bonjour à tous

Ma petite participation
5x300s sur Nova Cas 2020 hier soir avec UVEX(3) G300.

_novacas2020_20200811_836_Pierre Dubreuil.png
_novacas2020_20200811_836_Pierre Dubreuil.png (10.27 KiB) Viewed 775 times



Clear skies to all

Pierre
Dubreuil Pierre
 
Posts: 132
Joined: Sat Oct 01, 2011 12:34 pm

Re: Nova in Cassiopea (nova Cas 2020)

Postby David Boyd » Wed Aug 12, 2020 2:33 pm

The nova appears to have reached its maximum brightness in the visual band at V ~10.8 around 10th Aug. On 11th Aug its B-V colour index reddened to 1.93 compared to a mean of 1.65 over the previous 10 days while it was brightening. The spectrum on 11th Aug shows a further increase in continuum flux compared to 6th Aug. The H-alpha line flux has decreased to 8.1E-13 erg/cm2/sec.

novacas2020_20200811_897_D_Boyd.png
novacas2020_20200811_897_D_Boyd.png (134.23 KiB) Viewed 747 times

The P Cyg absorption dip on the H-alpha line extends to -700 km/s relative to its rest wavelength and has deepened with maximum absorption now at -240 km/s compared to -280 km/s on 6th Aug and -430 km/s on 1st Aug (see below). P Cyg profiles remain on H-beta and Fe II lines.

novacas2020_20200811_897_D_Boyd_Halpha_velocity.png
novacas2020_20200811_897_D_Boyd_Halpha_velocity.png (21.65 KiB) Viewed 747 times

David
David Boyd
 
Posts: 123
Joined: Wed Dec 11, 2013 5:50 pm

Re: Nova in Cassiopea (nova Cas 2020)

Postby Francois Teyssier » Wed Aug 12, 2020 4:34 pm

An ATel written by Steve Shore from the spectra gathered in the database: http://www.astrosurf.com/aras/Aras_DataBase/Novae/2020_NovaCas2020.htm

http://www.astronomerstelegram.org/?read=13939

ATel #13939; Steven N. Shore (Univ. di Pisa), Christophe Boussin, David Boyd, Christian Buil, Tim Lester, Jacques Michelet, Peter Somogyi (ARAS Group)
on 12 Aug 2020; 15:32 UT



We report the results of our continuing optical low and medium resolution spectroscopic monitoring of Nova Cas 2020 . We cover the interval reported in ATel #13903, #13905, #13919 and now extend it through Aug. 10. The spectra cover the period from 2020 Jul. 30.7 UT to Aug 11.9 UT with resolutions from 500 to 11000 in the spectral window 3700-8700A, exposure times of 1800 to 13000 sec, and S/N ranging from a low of about 20 to about 100 (peak line fluxes). The O I 7773A multiplet showed P Cyg profiles from the first spectra on Jul. 30.8. From Aug. 1.8 on, Fe II 5018, 5169 and other optical Fe II transitions showed P Cyg profiles. Aug. 8.3, the Ca II IRT showed weak emission, while O I 7773, 8446A both displayed P Cyg profiles (with absorption depths of around 60% and 25%, respectively), similar to the Pa series. The 7773A multiplet absorption was complex and broad, centered around -180 km/s but extending to nearly -500 km/s with emission extending to +300 km/s. On Aug. 4.9, blueshifted absorption appeared on the Na I D1,D2 lines at -190 km/s with an equivalent width EW = 0.1A. The absorption radial velocity was the same as all other P Cyg absorption on all Fe II lines (especially 5018, 5169A). On Aug. 6.8 the absorption had increased to EW = 0.5A with no change in radial velocity. The metal line absorptions displayed consistently lower radial velocity than the Balmer lines, whose asymmetric absorptions were deepest (Halpha, -250 km/s; Hbeta, -210) while extending to about -620 km/s; the emission to absorption equivalent width ratios were 3.8 (Halpha), 1.1 (Hbeta). Several blueshifted low ionization metal absorbers, e.g. Mg II 4481, Ti II 4764, and Si II 6347, 6371A, were present on Aug. 4 through Aug. 6 and persisted but were not well resolved in the later spectra. The Si II doublet showed weak emission through Aug. 6. There is a complex spectrum of weaker metal lines, all at low velocity, and the development of this nova shows similarities to nova DN Gem 1912 (McLaughlin 1965,POMic,9,113). No evidence was found of He I 5876, 6678, 7065 in any spectrum; on Aug. 11.9 the flux upper limit for He I 5876A emission was < 1.2E-15 erg cm-2 s-1 (uncorrected for extinction). As reported in Atel #13905, the interstellar DIBs are relatively strong including 5780 (EW=0.57A), 5793 (0.3A), and 6613A (0.37A). Based on the velocity range of the interstellar Na I D components (V(LSR)=-46,-9 km/s, ) and the width of the profile, 140 km/s, the LAB survey (http://adsabs.harvard.edu/abs/2005A%26A...440..775K) gives a total N(H)=8.2E21/cm^2. The H I displays a higher velocity, -65 km/s (mean), than the Na I components so this is a likely upper limit to the line of sight extinction. In light of the still rising optical flux and the lack of any forbidden lines (including [O I]), the nova may be a case of a highly inclined aspherical ejecta still in the optically thick stage with the initiation of the recombination wave known from other novae in the pre-maximum stage. Observations are continuing, the spectra are available at the ARAS Nova Database.

Steve comments:

this will be a nova to keep following and will surely lead to a paper (especially if there's any chance of more high resolution spectra in this next week). There are many more interesting, and diagnostic, features of these spectra than could be included in the ATel but I'll be working on that for you all. One thing -- if possible, keep pushoing on the 7000-8000A region, this is important for O I and He I (better still if you guys can extend out to 8700A for the Ca II triplet); it's unlikely that any data shortward of 4000A will provde useful (the exposure times will be just too long). My estimate, based on some continuum dereddening tricks, is certainly E(B-V)>1 and likely 1 <
E(B-V) < 1.5 (which is a pretty lousy bound but a start). The derived
E(B-V) from N_H is 1.2 (with a total-to-selective extinction ratio = 3) so this ain't so bad I guess (from the Guver and Ozel (2009) correlation;it was enough to give a limit of N_H since there are several different relations).



The AAVSO V lightcurve
NovaCes2020.PNG
NovaCes2020.PNG (6.09 KiB) Viewed 726 times






All the best
Francois Teyssier
 
Posts: 1345
Joined: Fri Sep 23, 2011 1:01 pm
Location: Rouen

PreviousNext

Return to Novae

Who is online

Users browsing this forum: No registered users and 1 guest

x