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Bright nova (mag. 6.4) in Hercules


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2 minutes ago, Astro Noodles said:

Thanks Jeremy. Are you saying, then, that the white dwarf was nearer to the Chandra limit than is normally observed?

Not necessarily. It all a matter of balance - these systems are dynamic. there is the rate of accretion onto the white dwarf and how much material is blasted off in the eruption. Generally, even though a nova has multiple eruptions, material continues to build up each time. So the WD hers more massive. At some point the WD reaches the Chandrasekhar limit and bingo!

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On 17/06/2021 at 13:26, skybadger said:

Anyone, whats the comparison between a ccd L filter and a V filter ? Is there a standard relationship or an experimental way of determining one, without having a V filter to hand ?

L filter transmits all wavelengths, V just greenish ones. So you can't really get a correlation as it depends on a number of factors including the colour (spectrum) of the star, as well as the comparison stars one uses. You might be able to do it for a single star, but the spectrum of many variable stars (especially this nova) varies with time.

If you don't have a V filter, then some people use a Green filter.

Or if using a DSLR, then use just the Green channel.

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Well I'm glad I managed to see it once at least !

Would it be fair to say that this nova and the one in Cassiopeia represent two opposite extremes of novae life cycles ?

 

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On 20/06/2021 at 21:21, John said:

Well I'm glad I managed to see it once at least !

Would it be fair to say that this nova and the one in Cassiopeia represent two opposite extremes of novae life cycles ?

 

They are different categories of nova. The one in Cas is a dusty nova, it seems.

The one in Her is unusual. ATel 14728 says its spectrum evolved rapidly during the first 6 days of the eruption. Initially, the nova showed signatures of belonging to the FeII class, but evolved to be more representative of the He/N class. Either ionization conditions increased unusually quickly or V1674 Her is a hybrid nova.

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  • 3 weeks later...
4 hours ago, JeremyS said:

Updated light curve from the BAA VSS database. Currently about 13th mag:

1116642424_NovaHer2021LC20210708.thumb.png.456085f8c6500e80746a46cf61d0c3eb.png

Thanks for the update @JeremyS

Is there any more confirmed info about what caused it to be so fast, and whether it is indeed the fastest on record? 

I know next to nowt about novas really so these may all be stupid questions, but will we eventually see (presumably in decades not years) some sort of emission nebulosity due to ejecta remnants? Are there any known rules as to which types of novae have visible remnants and why? 

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34 minutes ago, badhex said:

Thanks for the update @JeremyS

Is there any more confirmed info about what caused it to be so fast, and whether it is indeed the fastest on record? 

I know next to nowt about novas really so these may all be stupid questions, but will we eventually see (presumably in decades not years) some sort of emission nebulosity due to ejecta remnants? Are there any known rules as to which types of novae have visible remnants and why? 

Depends on how much energy is released by the thermonuclear detonation and the speed of expansion. All novae will have remnants in that they all blast material into space. But not all are visible. Depends as much as anything on how far away the nova is (too far= too faint), but also local factors like the quantity and density of the gas ejecta and how much energy there is to excite the gas. 

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12 hours ago, JeremyS said:

Depends on how much energy is released by the thermonuclear detonation and the speed of expansion. All novae will have remnants in that they all blast material into space. But not all are visible. Depends as much as anything on how far away the nova is (too far= too faint), but also local factors like the quantity and density of the gas ejecta and how much energy there is to excite the gas. 

Thanks @JeremyS

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