Betelgeuse dimmer

[Marvin Jenkins]

2 hours ago, PhotoGav said:

I was out observing last night and it is definitely on a magnitude par with Bellatrix (+1.6) rather than Rigel (+0.3) in the visible part of the spectrum. Still waiting for it to brighten (or explode 😉). My all sky cam (which is mono and responsive to longer wavelengths) shows it more on a brightness par with Procyon and Rigel than Bellatrix... Obscuration!

Looks like you have climbed onto the fence. Taking a fifty fifty position, very wise. I myself have taken to wearing a Sombrero whilst at the ep. Got to have something to stop getting burnt. Picture coming.....

M

[Nigella Bryant]

Official magnitude is now +1.66. Apparently Feb 21st is the date to watch as it should begin to brighten by then. If not something very peculiar is going on. See space weather for this update. 

[JamesF]

There are going to be a lot of disappointed people if it doesn't go pop

James

[SnakeyJ]

Very unlikely, but It would be quite special to see such a close SN in our lifetime - it would also be sad to loose an old friend of some 50+ years in my case.    

Quite a good article at Sky and Telescope from new years eve, but the light curve they plot for the last 50 years.   If we're fitting 1.66 now it is hitting an exceptional low.

[Nigella Bryant]

23 minutes ago, SnakeyJ said:

Very unlikely, but It would be quite special to see such a close SN in our lifetime - it would also be sad to loose an old friend of some 50+ years in my case.    

Quite a good article at Sky and Telescope from new years eve, but the light curve they plot for the last 50 years.   If we're fitting 1.66 now it is hitting an exceptional low.

It is an exceptional low. Still interesting even if it didn't go pop, to witness an historical low in our life time. 

[PhotoGav]

This might be a silly question, but I’ve been trying to work it out in my head and haven’t so far... why would a star dim before it exploded as a supernova anyway?!

[SnakeyJ]

Just looking around and the light curve from https://www.aavso.org/vsots_alphaori and there seems to be quite regular dips down to around 1.5 and a more exception dip to almost 2 in 1948 ish.

 

[andrew s]

23 minutes ago, PhotoGav said:

This might be a silly question, but I’ve been trying to work it out in my head and haven’t so far... why would a star dim before it exploded as a supernova anyway?!

No good reason at all. The outer layers of super giants are decoupled from the core by a thermal lag and  largely do their own thing. Obviously as the net energy output from the core changes it has a major influence on the outer layers over time.

However, once fusion in the core stops and it collapses it does so far too quickly for the outer layers to react until they are hit by the neutrino burst and shock waves.

Regards Andrew 

[Space Hopper]

I'm surprised by all this Betelgeuse hype, certainly on here.

Ok mainstream media whips up all this sort of thing, you expect that. I've read all sorts of nonsense about it.

Betelgeuse is a variable star : its normal for it to fluctuate in brightness periodically ??

It is not about to go Supernova.

I tell you what : lets come back to this thread in another million years or so, then we can all start getting excited 😆

 

[PhotoGav]

Good, that’s where I’ve got too. As far as I can see the expected output from a just-pre-supernova star would be constant and would brighten as the collapse starts to occur and core temperature and pressure rise significantly. Dimming is all to do with expansion, increasing surface area, decreasing surface brightness and increasing material in the star’s atmosphere. Giant stars can shed their outer envelopes in the latter stages of evolution, but would this cause significant dimming? I can’t see why.

Yup, it’s a good story for the media. However, Betelgeuse is about to explode as a supernova. It’s just that ‘about’ in astronomical terms can take many many thousands of years!!

[Paul M]

It is certainly interesting to see such a bright and, well, famous star showing such strong variability. I've always known about the variability but, TBH, I've never actually noticed it much - until now.

Perhaps it'll get lost in the rapidly approaching spring twilight before it bottoms out and turns round. Always strikes me how the winter stars get the short shift by the onset of spring but the summer stars last into winter!

And that's about where I am with Beetlejuice. I don't see its current behavior being anything to worry about. As @andrew s says above. The outer layers won't know anything about a core collapse until after it's happened. 

I can't remember where or when I read it but I have a half-fact in my mind that the energy being created in nuclear process in the Sun's core takes a very, very long time to reach the surface and be radiated into space. The photon's and particles suffer an age of absorption and re-emission on the outward journey. Years maybe? It's only going to take longer in a bigger star.

Ah, found an article: https://www.abc.net.au/science/articles/2012/04/24/3483573.htm

 

[Helen]

If somebody fancies a little photometry exercise there's a lot of data on lcogt archive https://archive.lco.global/?q=a&RLEVEL=&PROPID=&INSTRUME=&OBJECT=betelgeuse&SITEID=&TELID=&FILTER=&OBSTYPE=&EXPTIME=&BLKUID=&REQNUM=&basename=&start=2014-05-01 00%3A00&end=2020-02-10 23%3A59&id=&public=true

Helen

[PeterW]

We want a supernova as it’s one astro event that even the worst light pollution can’t put a dampener on. Likely it’ll brighten up again... should start in the next fortnight. Been fun to see it dim though.

Peter

[Nigella Bryant]

I'm just glad I've witnessed a deep low in my life time at 61, so that's why it's exciting to me not because it's going to go bag. I've never noticed it before. So it's interesting in that alone. For new people to astronomy it must also be fascinating to learn that stars are dynamic changing heavily bodies, hence, I'm a solar observer, imager too. Even the lows of our ordinary star the sun has us speculating when minimum will end and if it's a deep minium as cycle 24 has been. 

[Stub Mandrel]

I wouldn't get over-excited. The dimming is caused by reconfiguration of the Dyson sphere.

[JamesF]

2 minutes ago, Stub Mandrel said:

Dyson sphere.

That's the upright model with the big ball at the back instead of wheels, isn't it?

James

[PeterW]

53 minutes ago, JamesF said:

That's the upright model with the big ball at the back instead of wheels, isn't it?

James

Yeah, sometimes gets clogged up with dust... real [removed word] to clear out... maybe Betelgeuse will sort itself out.

Peter

[Marvin Jenkins]

6 hours ago, Space Hopper said:

I'm surprised by all this Betelgeuse hype, certainly on here.

Ok mainstream media whips up all this sort of thing, you expect that. I've read all sorts of nonsense about it.

Betelgeuse is a variable star : its normal for it to fluctuate in brightness periodically ??

It is not about to go Supernova.

I tell you what : lets come back to this thread in another million years or so, then we can all start getting excited 😆

 

I understand your comments, especially about mainstream media hype. But your comment “It’s not about to go Supernova” odd.

I find that as odd, as you may have found my slightly tongue in cheek post about it going bang any minute.

Do you know something the rest of the scientific world does not? Perhaps you have been given the heads up, in which case can you tell us how you know the future?

I understand that it is variable and due to this thread I know so much more about it’s behaviour, but you cannot say for certain that we are are not going to wake up tomorrow with a small second sun.

I will be happy to come back here in a million years and say to you ‘there you go, a DSO even harder to see than M1.✌️👍

[Paul M]

4 minutes ago, Marvin Jenkins said:

you cannot say for certain that we are are not going to wake up tomorrow with a small second sun.

No, it won't be tomorrow, it'll happen once Betelgeuse is lost in spring twilight. Then next Autumn all we'll see is an expanding and dimming remnant. 

Dang! Missed it!

What's the next supernova candidate on the list?

[Marvin Jenkins]

2 minutes ago, Paul M said:

No, it won't be tomorrow, it'll happen once Betelgeuse is lost in spring twilight. Then next Autumn all we'll see is an expanding and dimming remnant. 

Dang! Missed it!

What's the next supernova candidate on the list?

Loved it, made me laugh out loud. The reason, When I first looked through a scope I thought M1 has got to be the first, surely.

A year later I found it and used M Messier’s name in vain. How can that be the first M object? Then it dawned on me, it must have been amazing back in his day. After a couple of years can you believe what it will look like after the initial sn dies down?

Going to make M42 look like an amateur water colour next to a Hockney.

Marvin

[Paul M]

The closest supernova event in recent times was in the Large Magellanic Cloud. I remember it very well, the astronomy press were all over it. Unfortunately it was a southern hemisphere event and not a visually spectacular one at that, but the story is worth a read: https://en.wikipedia.org/wiki/SN_1987A

The radiation from the core collapse is short lived, momentary even. The main event is the expanding shell of the outer layers, now high energy plasma. Tiny and bright but as it cools and expands it dims into what we see as supernova remnant. Maybe still excited by electron beams from the poles of a neutron star. Wonderfully individual, complex and dynamic! 

The supernova is a flash in the pan, go look at Venus if you like bright stars... 🤣 

The remnant is for life!!

 

[RT65CB-SWL]

5 hours ago, Nigella Bryant said:

I'm just glad I've witnessed a deep low in my life time at 61, so that's why it's exciting to me not because it's going to go bag. I've never noticed it before. So it's interesting in that alone. For new people to astronomy it must also be fascinating to learn that stars are dynamic changing heavily bodies, hence, I'm a solar observer, imager too. Even the lows of our ordinary star the sun has us speculating when minimum will end and if it's a deep minium as cycle 24 has been. 

Well put. I explained something similar about the the life of stars, [in particular Betelgeuse], to my lady-friend a few weeks ago and she was equally impressed. 

[Older Padawan]

First look at Betelgeuse in quite a while and wow what a difference. Can't wait to see what it has in store for us next.

[Carbon Brush]

We are fortunate to live at an enlightened time. We can measure and discuss these things without fear.

A certain telescope builder in Italy (Galileo) once got into serious bother with the authorities.

He reported that certain night sky objects were not perfect spheres and changed with time.
The powers that be made him stay at home and say nothing.

 

[Marvin Jenkins]

My first night out in a little while and got carried away with a cloudless vista. Halfway through trying to find T2 Panstarrs I suddenly thought ‘Betelgeuse’. 
Now it is probably my imagination but it seems to be the same magnitude as my last observation or may now be a touch brighter.

The touch brighter may well be just observing conditions, but has it stabilised in the last week?

Marvin