Betelgeuse is one strange place

[hansolo0]

:!: Ah ! I have it now! I went back to Barnes and Nobles and found the magazine I had been reading. It was Astronomy NOW , not Astronomy magazine. It was the August '09 on page 34/35 I believe. The quote(s) I referred to about the brightness of " a million full moons" if B went supernova were there. Anyway I recomend reading it.

I should note that the article said it would likely be centuries (supernova) before occuring. I would think at 15% in 15 years it would be less than one century, and it sounded like the rate of shrinking was increasing!

 

[eburacum45]

The key to this shrinking might lie in the irregular shape of Betelgeuse. Note that from this link given earlier
http://astronomynow.com/news/n0907/29betel/

Ohnaka's unrivalled observations show that the gas in Betelgeuse's atmosphere is bouncing vigorously up and down in bubbles that are as large as the supergiant star itself, and could be responsible for the ejection of the massive plume into space.

The star is permanently erupting in bubbles that are the same size as its diameter. This is possible because the surface gravity of this gigantic star is only a fraction of a gee. Something that is emitting bubbles as large as itself could easily appear to shrink on occasion, as and when those bubbles fall slowly back towards the barycentre of the star. All this would happen on a very long timescale, as the star is bigger than the diameter of the orbit of Mars.

 

[hansolo0]

It's actually bigger than Jupiter's orbit. And this is kind of mind blowing, it's eruptions would extend out past neptune!

Does anyone know how many light years away it is?

 

[MeteorWayne]

The latest estimate is 640 +/- 140 light years based on VLA-HIPPARCOS data in 2008.

I've seen another estimate of 430 +/- 100 ly which may be based on more recent HIPPARCOS data, but I haven't found the source of that estimate yet.

 

[xXTheOneRavenXx]

What risk would this star pose to us when it goes supernova? Seems a bit far away, but we know there are trace evidence from other similiar events happening in Earth's past.

 

[MeteorWayne]

Not much. It seems clear that the poles are not pointing toward us and that's where the real danger zone is for a star at this distance.

 

[eburacum45]

The latest estimate is 640 +/- 140 light years based on VLA-HIPPARCOS data in 2008.

I've seen another estimate of 430 +/- 100 ly which may be based on more recent HIPPARCOS data, but I haven't found the source of that estimate yet.

Hipparchos data is unreliable when dealing with variable or double stars. The satellite took readings when the satellite was on different sides of the Earth's orbit, so these readings were several months apart. This means that any star that moved in the meantime (a binary for instance) or if the star physically changes brightness or shape (as in Betelgeuse) the distance is unreliable.
see this abstract
Systematic biases and uncertainties of Hipparcos parallax
quote
We have established good models for major error sources of Hipparcos parallax, such as zonal bias, binary jitters, and luminosity-dependent errors.

I have no idea what 'zonal errors' are.

 

[robnissen]

Re: Betelgeuse shrinking??

This is the first time such observations of any star has been possible, so it's all unknowns right now.

That statement is not accurate. There have been such observations of a star for at least the last few hundred years. That star is 93 million miles away and the leading cause of skin cancer on earth.

 

[MeteorWayne]

Well that's a bit different since our star is not in the red giant phase, so it's diameter show microspcopic variations over that same period.

Of course, still a nice technicality catch

 

[xXTheOneRavenXx]

I just thought even though Betelgeuse's poles were not pointed at us that at it's distance we may still feel some sort of affects of it going supernova. I would imagine that though the majority of the material would escape in polar jets, that there is some amount of material that is spread in all directs from the surface when a star does go through this final phase and just not at the poles... but I could be wrong.

 

[MeteorWayne]

Mostly light for us