Betelgeuse is now the faintest it has been in the last 25 years of observation. The behaviour is described in ATEL #13337 (Astronomer's tele message).

The Fainting of the Nearby Red Supergiant Betelgeuse

...

Betelgeuse and Antares are the two nearest red supergiant core-collapse Type-II supernova (SN II) progenitors. Photometry from this season shows the star has been declining in brightness since October 2019, now reaching a modern all-time low of V = +1.12 mag on 07 December 2019 UT. Betelgeuse undergoes complicated quasi-periodic brightness variations with a dominant period of ~420 +/-15 days. But also Betelgeuse has longer-term (5 - 6 years) and shorter term (100 - 180 days) smaller brightness changes. Currently this is the faintest the star has been during our 25+ years of continuous monitoring and 50 years of photoelectric V-band observations.

... more @ link

I guess there is not a renewed super nova in the works??
Not sure of any impact from 620 light years away. Poor Orion losing some glitter.

I have no idea how a core collapse begins or what that does to the light curve*. "Supergiant drama queen" sprang to mind immediately, though.

* I'm guessing that the collapse begins when the fusion fuel runs out. This would imply a temporary drop in luminance as the collapse proceeds towards the explosive bounce of the type II supernova.

Isn't it normal for a dying star?

Somewhere I've read that when it explodes it would be visible, by the naked eye, on Earth during day time, which is pretty cool.

Think it already did that a while back but not sure of the next step.... if I recall a brown dwarf .

Macdoc wrote:Think it already did that a while back but not sure of the next step.... if I recall a brown dwarf .

Read the first sentence of the tele message snippet above again. It's a candidate to explode as a type II supernova. It's currently more than 10 solar masses and a brown dwarf is not going to be its future state. After detonation, not only will Betelgeuse be visible during the day, but it will rival the Moon for the second-brightest object in the sky.

ah progenitors....dah ...glad we are a ways away tho the light show will be long delayed

It will probably result in a black hole at that mass, dependent on how much mass it sheds during nova. The mass limit of a neutron star is the Tolman-Oppenheimer-Volkoff limit, and that's currently thought to be about 2.2 solar masses. It's possible that it could result in a quark star, but these are theoretical only at this point. Beyond that, it's a black hole.

ETA: The mass limit of a brown dwarf is actually tiny. Even Sol will not become a brown dwarf when it dies, but a white dwarf. A brown dwarf is a body whose mass lies between that of the heaviest gas giants and the lightest stars, around 0.4-0.5 solar masses.

been too long since I caught up on stellar evolution.

It's not a good time to be from a small planet in the vicinity of it, that's for sure.

Please let this be happening. I want to see this!

I've been doing the sceptic's version of praying for this since I was about nine years old, when I first read about John Flamsteed, who apparently observed the supernova of Cassiopeia A in 1680.

Please let this be happening. I want to see this!

for all you know it may well have centuries ago.

642.5 light years

Ironclad wrote:642.5 light years

That's just the midpoint estimate, because it's actually impossible to tell how far it is away within more than about fifty light years. It's too distant for parallax measurements to do better and too highly variable for accurate spectroscopic methods either. Estimates of its size and mass have pretty big error bars too.

I recall us having a very similar discussion here about eight years ago too, where the conclusion was not to wait up on there being a supernova. It might be on the brink of collapsing or have another hundred thousand years left in It. There's just no way to tell how long without knowing what's going on in the core of the star.

Besides, Gamma Velorum is probably going to go first, although that might keep you waiting a few tens of thousand of years too.

Oh

To see how the current dimming is probably not going to lead to an imminent supernova there's a model of a red giant star (like Betelgeuse) that shows how surface intensity varies over years of time in this cool movie in mp4 format and taken from this talk.

If it kicks off tonight, a lot of people are going to shit themselves.

hehe - Australia already missed...

If there's intelligent life on surrounding stars maybe they'll do something big before the finale rather than go out in a wimper and that might be a signal shit is going down?