TCP J20210770+2914093 a nova in Vul

Alerts and Monitoring of Novae

Re: TCP J20210770+2914093 a nova in Vul

Postby Robin Leadbeater » Sat Jul 31, 2021 10:26 pm

The nova has now been given an official designation
V606 VULPECULAE = NOVA VULPECULAE 2021 = TCP J20210770+2914093
CBET #5007 references my spectrum taken 10 hours after it was discovered
http://www.cbat.eps.harvard.edu/iau/cbe ... 005007.txt

Cheers
Robin
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Re: TCP J20210770+2914093 a nova in Vul

Postby Juan Jose Pueyo » Sun Aug 01, 2021 12:18 pm

I took a new spectrum of Nova Vul 2021, five days after the first one. The continuous spectrum and luminosity have increased (Magnitude: 12 to 10.4). Spectral lines have also varied: In the last spectrum the only line in emission is H-alpha, but with a relatively diminished intensity. The rest of the Balmer lines as well as the iron lines (which were in emission five days ago) are now, all of them, in absorption. I suppose it must be the relationship between what happens in the stellar wind of the nova and in the shell (now more expanded). Is that so?
However, I do not see this effect in the spectra of other observers. Conditions in which I got both spectra were similar ..... (?)
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Re: TCP J20210770+2914093 a nova in Vul

Postby Robin Leadbeater » Sun Aug 01, 2021 2:24 pm

That is an interesting dramatic change. (I have had no clear skies for a week.) I checked the BAA,ARAS and AAVSO databases and I cannot find any spectra later than yours for 20210726 and 20210731. ATel# 14816 mentions Fe lines with P Cygni profiles on 20210728 so the change to absorption must have taken place between 28 and 31 July

Cheers
Robin
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Re: TCP J20210770+2914093 a nova in Vul

Postby Robin Leadbeater » Mon Aug 02, 2021 1:26 pm

A spectrum last night confirms the dramatic change in the spectrum. Except for a relatively weak narrow H alpha emission, all lines previously in emission are either missing or in net absorption

Cheers
Robin

novavul2021_20210724-0802_Leadbeater.png
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Re: TCP J20210770+2914093 a nova in Vul

Postby Robin Leadbeater » Tue Aug 03, 2021 1:00 pm

The H alpha emission has weakened further and is now showing a P Cygni profile with velocity (emission max-absorption min) of ~600km/s. The spectrum looks similar to a G/K star photosphere but with some additional absorption lines, particularly in the red at ~7106 and 7766.

Cheers
Robin

novavul2021_20210802_997_Leadbeater.png
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Re: TCP J20210770+2914093 a nova in Vul

Postby Juan Jose Pueyo » Tue Aug 03, 2021 1:48 pm

Seeing the magnitude evolution, it seems that the luminosity of the nova is stabilizing. The emission lines decrease while spectral background and absorption lines increase. Juan Jose
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nova Vulpeculae 2021 evolution 3.jpg
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Re: TCP J20210770+2914093 a nova in Vul

Postby Robin Leadbeater » Tue Aug 03, 2021 4:35 pm

Juan Jose Pueyo wrote:Seeing the magnitude evolution, it seems that the luminosity of the nova is stabilizing.


Hi Juan Jose,

Should the date for the last spectrum be 02/08/2021 ?

V is steady but B is decreasing and R/I are still increasing. (It is cooling down?)

nova_Vul_2021_photometry.png
nova_Vul_2021_photometry.png (48.7 KiB) Viewed 801 times


I think there could be a problem with the response correction. Your continuum shape looks quite different to mine
(EDIT: the problem could be partly with my spectra. I am seeing some consistent differences between the reference stars I am using which I need to investigate)

novavul2021_20210716-0802_Leadbeater.png
novavul2021_20210716-0802_Leadbeater.png (74.75 KiB) Viewed 801 times


Cheers
Robin
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Re: TCP J20210770+2914093 a nova in Vul

Postby Juan Jose Pueyo » Wed Aug 04, 2021 8:19 am

Hi Robin,
Sorry. The third spectrum is from day 2 (not 3).
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Re: TCP J20210770+2914093 a nova in Vul

Postby David Boyd » Wed Aug 04, 2021 11:03 am

Last night, 3rd August, I measured Nova Vul 2021 at V=10.97, B-V=1.14, almost a magnitude fainter than 48 hrs before and slightly redder.

The following LISA spectrum (R~1062) was calibrated in absolute flux using this V magnitude and response corrected with the B9III MILES star HD192907 recorded at the same airmass as the mid-time of the nova spectrum. H-alpha has a strong P-Cyg absorption dip at -320 km/s which now falls within the ~3000 km/s FWZI of the line. FeII multiplets 42, 49 and 74 are prominent with just-resolved P-Cyg dips. There are also emission features at ~5526A, ~5662A and ~7117A, all with P-Cyg dips, which I have not been able to identify in the WIlliams list of nova emission lines. Suggestions?

David

novavul2021_20210803_918_D_Boyd_flux.png
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novavul2021_20210803_918_D_Boyd_velocity.png
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Re: TCP J20210770+2914093 a nova in Vul

Postby Juan Jose Pueyo » Sun Aug 08, 2021 3:03 pm

I obtained a fourth spectrum, this one after the decrease in luminosity of the nova. The continuous background has diminished considerably. In addition to the initial iron emission lines (Fe II), new lines have appeared that I have not been able to accurately identify.
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nova Vulpeculae 2021 evolution 4.jpg
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