Bright nova (mag. 6.4) in Hercules

[robin_astro]

The spectrum was pretty featureless at first but soon developed  P Cygni lines and then quickly moved to just strong broad emission lines. It is very striking  looking at it tonight. Here is a 10 min raw spectrum image using the ALPY600. The very bright blob is H alpha

Cheers

Robin

 

[Malpi12]

Morning all ! Brief report before bed

2:30am and I had almost given up hope, then the overcast started to clear with passing clouds and I can say that it continues to decline.  
Now much less than the mag 8.5 HD175919/HIP93033
Not far away are two unnamed in Stellarium at mag 9.5 and, further away, mag 9.0 **,  on this basis I would give it 9.0 but as remarked earlier my eyes are not good at this so I will hope that I have got some lucky subs to stack tomorrow.

**update - I think they are mag 9.512 - Gaia DR2 4508099383033253632 and mag 8.977 Gaia DR2 4511094899382630144 in CdC.

PS  @robin_astro what are the implications for the future of it being similar to P Cyg, I have just wiki_ed  it and that one got to magnitude 3 !

 

[Jamgood]

I had a quick look after finishing my imaging plan. Just managed to grab a couple of shots of it before the sky got too washed out.

[Malpi12]

Who needs bed when there is interesting astro to be done !

From  wiki :-
"After shining for only a few million years (compared to several billion years for the Sun) they erupt in a supernova. The recent supernova SN 2006gy was likely the end of an LBV star similar to P Cygni but located in a distant galaxy
...
It has been identified as a possible type IIb supernova candidate in modelling of the fate of stars 20 to 25 times the mass of the Sun"

But before we get too excited I think Robin may a have been referring to this  spectroscopic bit :-
wiki again : "P Cygni gives its name to a type of spectroscopic feature called a P Cygni profile, where the presence of both absorption and emission in the profile of the same spectral line indicates the existence of a gaseous envelope expanding away from the star."

[JeremyS]

This nova has now been officially designated V1674 Her

[Littleguy80]

38 minutes ago, JeremyS said:

This nova has now been officially designated V1674 Her

Thanks Jeremy  

[JeremyS]

Kato-san, who runs VSNet in Japan (I wonder how many Taks he has 🤔), suggests this might be the fastest nova ever.. he speculates that t3 (number of days to drop 3 mags) is likely to be ~3 days. Nova Cyg 1975 (V1500 Cyg) was very fast at 3.6 days.

I had it at mag 8.8 at 22.45 last night

[Littleguy80]

23 minutes ago, JeremyS said:

Kato-san, who runs VSNet in Japan (I wonder how many Taks he has 🤔), suggests this might be the fastest nova ever.. he speculates that t3 (number of days to drop 3 mags) is likely to be ~3 days. Nova Cyg 1975 (V1500 Cyg) was very fast at 3.6 days.

I had it at mag 8.8 at 22.45 last night

Are fast novas less likely to brighten again?

[JeremyS]

12 minutes ago, Littleguy80 said:

Are fast novas less likely to brighten again?

Yes I think that’s right. It’s slow novae, which are often pretty dusty, that tend to show rebrightenings. The light curve of V1500 Cyg was pretty smooth.

But who knows? V1674 Her seems to have thrown away the script and is extemporising *

* second half of this sentence about extemporising is a comment from Starlight Nights by Leslie Peltier, which like @mikeDnight, I can recite many passages from. He discovered novae and comets and was a variable star observer. Anyone not read it should read it!

[Stu]

7 minutes ago, JeremyS said:

Yes I think that’s right. It’s slow novae, which are often pretty dusty, that tend to show rebrightenings. The light curve of V1500 Cyg was pretty smooth.

But who knows? V1674 Her seems to have thrown away the script and is extemporising *

* second half of this sentence about extemporising is a comment from Starlight Nights by Leslie Peltier, which like @mikeDnight, I can recite many passages from. He discovered novae and comets and was a variable star observer. Anyone not read it should read it!

Thanks Jeremy. I didn’t have to Google extemporising, honest guv!

[Astro Noodles]

I managed to grab a few subs between clouds just after midnight.

I am glad I have a record of this unusual event.

Even with my bloated stars I can see that it has become very red.

[robin_astro]

8 hours ago, Malpi12 said:

I think Robin may a have been referring to this  spectroscopic bit :-
wiki again : "P Cygni gives its name to a type of spectroscopic feature called a P Cygni profile, where the presence of both absorption and emission in the profile of the same spectral line indicates the existence of a gaseous envelope expanding away from the star."

Yep that's right.  P Cygni is a Luminous Blue Variable, a hot supergiant star which produces powerful stellar winds which glow in H alpha. Here is an example of its H alpha line by John Foster from the BAA database

https://britastro.org/specdb/data_graph.php?obs_id=6544

This is a similar (though temporary and much more powerful) situation. We see the glow directly from the material thrown out sideways by the explosion which produces an emission line. The material coming directly towards us though is lit from behind so we see an absorption line. This is blue shifted by the doppler effect so we see the combination of an emission line and a blue  shifted absorption line - the P Cygni line profile. Here they are in Hugh Allen's spectrum of the nova for example

https://britastro.org/specdb/data_graph.php?obs_id=9977

but in my spectrum last night the emission now completely dominates and we no longer see the P Cygni profiles shape. (I'll post the processed spectrum later)

Cheers

Robin

[Pixies]

1 hour ago, robin_astro said:

but in my spectrum last night the emission now completely dominates and we no longer see the P Cygni profiles shape. (I'll post the processed spectrum later)

Do you mean the absorption 'dip' is obscured by the dominance of the emission line, or that the gas cloud has dispersed significantly enough to reduce its absorption?

[robin_astro]

1 hour ago, Pixies said:

Do you mean the absorption 'dip' is obscured by the dominance of the emission line, or that the gas cloud has dispersed significantly enough to reduce its absorption?

Good question but its complicated and above my level of expertise so I will hand you over to Prof Steve Shore who did a running commentary of the evolution of the spectrum of Nova Del 2013 based on amateur spectra

http://www.astrosurf.com/aras/novae/Nova2013Del.html

Here is my spectrum from last night with the Hydrogen lines marked (It is not poor resolution. The lines really are that wide !) 

This is the H alpha line profile plotted in velocity space.

The velocities at the edge of the line are ~+-4500 km/s, very high for a Nova (almost Supernova territory, though this is a very different process. In a type Ia supernova the whole white dwarf explodes. Here only a thin shell of material (that has built up on  the surface of the white dwarf from the companion star) has detonated.  The w shaped wiggles on the top of the line profile contain information about the 3D shape of the explosion. (I think it may mean it was a bipolar shape but don't quote me !)

Cheers

Robin

EDIT:  We are seeing the full range of +- velocities in the emission line profiles  both towards and away from us now so I guess the ejecta must optically thin (transparent) now 

Edited June 15, 2021 by robin_astro

[Stu]

37 minutes ago, robin_astro said:

Good question but its complicated and above my level of expertise so I will hand you over to Prof Steve Shore who did a running commentary of the evolution of the spectrum of Nova Del 2013 based on amateur spectra

http://www.astrosurf.com/aras/novae/Nova2013Del.html

Here is my spectrum from last night with the Hydrogen lines marked (It is not poor resolution. The lines really are that wide !) 

This is the H alpha line profile plotted in velocity space.

The velocities at the edge of the line are ~+-4500 km/s, very high for a Nova (almost Supernova territory, though this is a very different process. In a type Ia supernova the whole white dwarf explodes. Here only a thin shell of material (that has built up on  the surface of the white dwarf from the companion star) has detonated.  The w shaped wiggles on the top of the line profile contain information about the 3D shape of the explosion. (I think it may mean it was a bipolar shape but don't quote me !)

Cheers

Robin

EDIT:  We are seeing the full range of +- velocities in the emission line profiles  both towards and away from us now so I guess the ejecta must optically thin (transparent) now 

Fascinating stuff! I had no idea you could get so much info from the spectrum. Thanks 🙏 

[John]

Very interesting stuff

I'm hoping to get my first (and possibly last !) glimpse of this nova tonight. Previous attempts have been clouded out plus that part of the sky takes a long time to become visible from where I observe due to some large conifers

Maybe I'd better use the 12 inch dob for tonights attempt, given the rate at which the nova is fading !

 

 

[michael.h.f.wilkinson]

41 minutes ago, robin_astro said:

Good question but its complicated and above my level of expertise so I will hand you over to Prof Steve Shore who did a running commentary of the evolution of the spectrum of Nova Del 2013 based on amateur spectra

http://www.astrosurf.com/aras/novae/Nova2013Del.html

Here is my spectrum from last night with the Hydrogen lines marked (It is not poor resolution. The lines really are that wide !) 

This is the H alpha line profile plotted in velocity space.

The velocities at the edge of the line are ~+-4500 km/s, very high for a Nova (almost Supernova territory, though this is a very different process. In a type Ia supernova the whole white dwarf explodes. Here only a thin shell of material (that has built up on  the surface of the white dwarf from the companion star) has detonated.  The w shaped wiggles on the top of the line profile contain information about the 3D shape of the explosion. (I think it may mean it was a bipolar shape but don't quote me !)

Cheers

Robin

EDIT:  We are seeing the full range of +- velocities in the emission line profiles  both towards and away from us now so I guess the ejecta must optically thin (transparent) now 

Nice result. I lack a spectrograph, but inserting a UHC filter into the optical path can make the nova seem to brighten with respect to the other stars quite distinctly, indicating that the spectrum is dominated by  emission lines. I did this for Nova 2013 Del, and you could really see a shift from continuum to line emission

[badhex]

I have to say this is all fascinating. This is also my first nova, so all the better for how unusual it is! I may have to have another go tonight if it's clear, full cloud here at the moment. 

[Malpi12]

59 minutes ago, robin_astro said:

 ( lots of interesting stuff  )

Wow! Thank you, amazing  👍

[John]

32 minutes ago, badhex said:

I have to say this is all fascinating. This is also my first nova, so all the better for how unusual it is! I may have to have another go tonight if it's clear, full cloud here at the moment. 

If you want a 2nd one, and a contrasting one, nova V1405 Cas is still bright and easy to find in Cassiopeia.

 

[badhex]

Thanks John! If I manage to get out tonight I will take a look. I noted mentions of it in this thread and had been wondering if it was still around. 

[Malpi12]

8 hours ago, John said:

Maybe I'd better use the 12 inch dob for tonights attempt, given the rate at which the nova is fading !

Good luck, and we may have a bit longer yet, looks like it may be leveling off a bit : data from AAVSO

 

Edited June 15, 2021 by Malpi12

[Littleguy80]

Just picked it up in the 80mm refractor at 16x. It looks dimmer again than Sunday night. HD 176156, listed at Mag 9.5 in SkySafari, looks about the same to me. 

[John]

Managed to find it OK with the 120mm refractor tonight. My estimate is around magnitude 9.5 as well.

Got a bit distracted by the Summer Beehive cluster and Blue Raquetball planetary nebula before getting to the nova

 

[badhex]

Had another look tonight. Sky not great to start with, but obviously started to clear up once  Regardless I did spend a while with the nova, at first the haze made it almost too hard to pick out. Once it cleared a bit it was visible, but clearly dimmer again than Sunday night/Monday AM.