Nova

[andrew63]

I note that a few of us over the past two nights have found the nova after it's peak about the same mag as 29 Vul at 4.8 and a few including myself a bit less bright - although i'm not great at this. I wonder if differing optical equipment can play any part and would the observers differing eye characteristics make a difference?

I have observed 'underestimated' by comparison the novas brightness and did not find it as 'bright' as 4.5 on friday. I guess it helps when you can pool together many observations to iron out any inconsistencies.

andrew

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[Physicist13]

I read somewhere that the star was mag 17 before nova....

if it was as bright as the sun before nova that to my calculations places it 9000 light years away.

does that sound right to the physics experts out their?

mark

Mark,

most likely, it was a white dwarf star in a binary system, accumulating mass from the companion untill such a time that enough mass/density was accreted to give rise to nuclear fusion..this is when it goes nova. If its a "standard" nova of this type then the luminosity is known so the dist can be estimated from the apparant brightness. If not then it will be harder to calc the dist, although rough estimates can be given.

As for the "brightness" observations these are notoriously prone to error! you can see how much scatter thaere is on the plots already. The best is to compare the measured brightness with a nearby star(s) of known brightness. Making sure neither are saturated in the exposure! Otheriwse the you have to calibrate the whole imaging system very well.

P

[andrew63]

Just been looking at some of these reports - and you can understand the variations in the curve !

AAVSO -- WebObs Search Results

andrew

[Ouroboros]

Our eyes certainly vary. With unaided eyes I can't see a mag 6.0 star even with averted vision in a dark site. I think I get down to about mid to high fives on sensitivity.

[bish]

It did clear again last night, so I had another look. I have been using the same stars as mark for a guide. My estimates so far are 16th 4.6, 17th 4.9, 18th 5.1 (used 22 Vul for this estimate). It's a tricky business trying to estimate the brightness as some stars appear fainter/brighter than the mag suggests (compared to others).

[Ouroboros]

1376896246' post='2019785']I read somewhere that the star was mag 17 before nova....

if it was as bright as the sun before nova that to my calculations places it 9000 light years away.

does that sound right to the physics experts out their?

mark

Yes, sounds right. 880 light years I get. Do we know its absolute mag?

[mdstuart]

9000 is a lot bigger than 880!

More importantly are the astronomers in the andromeda galaxy working out how far away the milky way is using this nova?

Mark

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[andrew63]

It did clear again last night, so I had another look. I have been using the same stars as mark for a guide. My estimates so far are 16th 4.6, 17th 4.9, 18th 5.1 (used 22 Vul for this estimate). It's a tricky business trying to estimate the brightness as some stars appear fainter/brighter than the mag suggests (compared to others).

I think everyones observations are valid - it can be a bit of a challenge and they are after all estimates ! It's lucky for us to have such a rare event as bright as this to observe

andrew

[Ouroboros]

9000 is a lot bigger than 880!

More importantly are the astronomers in the andromeda galaxy working out how far away the milky way is using this nova?

Mark

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Oops! Add a nought.

Not for another 2.5 million years they're not! :-)