Nova Sgr 2021b - Second nova of the year in Sgr

Alerts and Monitoring of Novae

Nova Sgr 2021b - Second nova of the year in Sgr

Postby Francois Teyssier » Tue Apr 06, 2021 7:17 am

Please use Nova Sgr 2021b as OBJNAME

ATEL #14513 ATEL #14513

Title: Spectroscopic Classification of PNV J17581670-2914490 as a
classical nova
Author: Kenta Taguchi, Miho Kawabata, Masayuki Yamanaka, Keisuke Isogai
(Kyoto University)
Posted: 6 Apr 2021; 05:25 UT
Subjects:Optical, Cataclysmic Variable, Nova, Transient

We report <a href="">our
spectrum</a> of the transient PNV J17581670-2914490.
We obtained the spectrum on 2021-04-05.828 UT using the fiber-fed integral field spectrograph (KOOLS-IFU; <a href=""
target="_blank">Matsubayashi et al. 2019</a>) mounted on the 3.8-m Seimei telescope (<a href=""
target="_blank">Kurita et al. 2020</a>) at Okayama Observatory of Kyoto

As reported to <a href=""
target="_blank">CBAT</a>, this transient was discovered by Andrew Pearce at 8.4 mag (unfiltered) on 2021-04-04.825 UT (see also <a href=""
target="_blank">vsnet-alert</a> for detail). Rob McNaught reported non-detection on 2021-04-02.776 UT (unfiltered limiting mag 11.0). Seiichiro Kiyota reported multicolor photometry results: B = 9.03, V = 8.02, and Ic = 6.82 (these results were reported at 2021-04-05.4188 UT, but the observation time is not reported). Andrew Pearce also reported multicolor photometry results:
V = 8.08 on 2021-04-05.482 UT, B = 9.16 on 2021-04-05.483 UT, and I = 6.50 on 2021-04-05.484 UT. <a href=""
target="_blank">ASAS-SN Sky Patrol</a> also reported photometries: in average, it was g = 14.25 on 2021-04-05.290 UT and g = 14.22 on 2021-04-05.458 UT.

<a href=""
target="_blank">Our spectrum</a> shows Balmer lines, Fe II lines, and the Na I D line. Note that the interstellar extinction is not corrected. The H&alpha; line has the P-Cygni profile, whose absorption component is blue-shifted by &sim;1000 km/s from the redder emission component (for convenience, we plot the spectrum in two ways: the blue curve is "rest" spectrum in which the emission peak of the H&alpha; line is offset to its rest wavelength to correct the radial velocity of the target. the green one is red-shifted by 1000 km/s from the blue one, for the visibility of absorption components).

Fe II lines have absorption profiles whose wavelengths are consistent with the 1000 km/s blue-shift.
The Na I D line has a combined profile of a "rest" absorption component and a broad absorption component which is blue-shifted by &sim;1000 km/s from the "rest" one.
Hidehiko Akazawa also reported <a href=""
target="_blank">his spectrum</a>, confirming our results.

According to our spectrum and the brightness, we conclude that this object is a classical nova. The spectrum is similar to those of the slow nova V1280 Sco in the early stage (<a href=""
target="_blank">Naito et al. 2012</a>, <a href=""
target="_blank">Hanindyo et al. 2008</a>).

Our Spectrum: ... vj1758.pdf
Francois Teyssier
Posts: 1406
Joined: Fri Sep 23, 2011 1:01 pm
Location: Rouen

Re: Nova Sgr 2021b - Second nova of the year in Sgr

Postby Joan Guarro Flo » Fri Apr 09, 2021 2:38 pm


With not more good conditions I I have observer Nova Sgr 2021b this last morning.

Those are the results, it seems this spectra show an evolution from the first that we can see in the François' message.

Cheers, J.Guarro.
NOVA SGR 2021B_1.jpg
NOVA SGR 2021B_1.jpg (84.89 KiB) Viewed 351 times
NOVA SGR 2021B_2.jpg
NOVA SGR 2021B_2.jpg (98.94 KiB) Viewed 351 times
NOVA SGR 2021B_3.jpg
NOVA SGR 2021B_3.jpg (73.57 KiB) Viewed 351 times
NOVA SGR 2021B_4.jpg
NOVA SGR 2021B_4.jpg (55.28 KiB) Viewed 351 times
NOVA SGR 2021B_5.jpg
NOVA SGR 2021B_5.jpg (101.93 KiB) Viewed 351 times
Joan Guarro Flo
Posts: 402
Joined: Thu Nov 03, 2011 8:50 pm

Re: Nova Sgr 2021b - Second nova of the year in Sgr

Postby Paolo Cazzato » Fri Apr 16, 2021 8:32 am

Hallo everybody,
here my comparison at low resolution of this Nova taken from 3800A to 7900A. At low resolution I noticed an incrase of the basic lines and a splitting of the h alpha line. I also noticed an incrise of the OI (?) line at the extreme end of the spectrum. Would it be possible an overlap of the Mg line at 7890A in your opinion?
confronto riga H-Alpha.jpg
confronto tutto spettro.jpg
Paolo Cazzato
Posts: 6
Joined: Sat Nov 14, 2015 10:58 am

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