What happens when Betelgeuse explodes?

What happens when Betelgeuse explodes?(medium.com)

124 points by varmais 11 years ago | 50 comments

adwn 11 years ago |

To get a feel for the tremendous size of that star: https://en.wikipedia.org/wiki/File:Star-sizes.jpg

jahnu 11 years ago | |

I feel those images are a little misleading. One might erroneously assume there is a dense surface akin to our star at the outer edge of these massive stars but..

"In the outer reaches of the photosphere the density is extremely low, yet the total mass of the star is believed to be no more than 20 M☉. Consequently, the average density is less than twelve parts per billion (1.119 × 10−8) that of the Sun. Such star matter is so tenuous that Betelgeuse has often been called a "red-hot vacuum"."

https://en.wikipedia.org/wiki/Betelgeuse#Density

gunn 11 years ago | | |

Also: "estimates of its mass are poorly constrained, but range from 5 to 30 times that of the Sun". Amazing for having on the order of 16 billion times its volume.

yourad_io 11 years ago | | |

M☉ = Solar Mass[1]. Huh.

> astronomers have the worst conventions in the world (for largely “historical reasons”)[2]

You don't say.

[1] http://en.wikipedia.org/wiki/Solar_mass

[2] article

hellbanner 11 years ago | | |

Those images accurately show size, correct? Stars are big.

ramidarigaz 11 years ago | |

Also, for anyone who has an Oculus Rift (or has access to one), Titans of Space does a really good job of depicting things like this.

agumonkey 11 years ago | |

Still hard to have a carnal comprehension of these. I had a tiny feeling of vertigo though.

xenophonf 11 years ago | |

Holy cow - the star's circumference is about as big as Jupiter's orbit!

https://en.wikipedia.org/wiki/Betelgeuse#Diameter

john_b 11 years ago | |

My favorite fact about Betelgeuse is that light takes 1.5 hours to travel the distance of its diameter.

d_theorist 11 years ago |

"Betelgeuse is already one of the brightest stars in the night sky, sitting somewhere around the 8th or 9th brightest star in the night sky. (These lists don’t include the Sun, which is somewhat obviously always the brightest object in the sky.)"

A good point, although it is fairly rare to see the sun in the night sky these days.

whoisthemachine 11 years ago | |

Depending on your definition of "night sky", I would argue it's incredibly easy to see in the night sky!

Starwatcher2001 11 years ago |

The remnents of the supernova that occurred in 1054 is known as the "Crab Nebula", AKA M1 on Messier's catalog.

I remember observing this from my back garden some 10 years ago with a small telescope, but that's quite difficult now due to light polution. It's getting hard for people to see stars in many big cities, let alone fainter objects.

agrona 11 years ago | |

There's a guide (in development) at eyesonthesky.com[1] aimed at newcomers, who may be using poor telescopes in poor atmospheric and lighting conditions. I've been following it quite successfully from my back yard in Seattle. It focuses on the brightest galaxies and nebulae, interesting clusters, and binary stars.

[1] http://eyesonthesky.com/StarCharts/FirstLightGuides.aspx

astletron 11 years ago |

"Nighttime will be a different story. The brightness of Betelgeuse’s supernova is about the same as the quarter moon."

This will last maybe a couple of weeks, but we don't expect it for 100K years.

themartorana 11 years ago | |

No, but with billions of stars in our own galaxy, and more beyond, wouldn't (my misunderstanding of) the probability of witnessing a past supernova event during one's lifetime be higher than it feels like it is?

jerf 11 years ago | | |

First of all, the "pastness" of looking out into space doesn't really affect probability of witnessing them.

Second, supernova occur quite frequently: http://en.wikipedia.org/wiki/List_of_supernovae That's not even a complete list, just the "important" ones. The odds of one occurring within our lifetime that is naked-eye visible are really quite good. The odds of it being spectacular much less so. It's likely to just be a point in the sky that wasn't there last week and won't be there next week.

onion2k 11 years ago | | |

Not really. There are a huge number of stars, but most of them are moving away so fast that the light from their death wouldn't ever reach us, and their light would be shifted in to parts of the spectrum we can't see. Similar to Olbers' Paradox - http://en.wikipedia.org/wiki/Olbers%27_paradox

smeyer 11 years ago | | |

It depends in part on what you mean by "witness" a supernova. We discover supernovae all the time (hundreds a year), but pretty much all of those are too faint to be seen with the naked eye. There's a decent chance of seeing a supernova visible with the naked eye in your lifetime, but a pretty small chance of one as bright as betelgeuse.

nsxwolf 11 years ago |

The transition of the star to nebula will also permanently alter the appearance of the constellation Orion, which is both exciting and sad.

rquantz 11 years ago | |

I like the maxim "this too shall pass." It's easy to think of on a generational level - our fathers' generation will disappear, and so will ours. But on the level of a civilization, it becomes both stranger and sadder. Orion is a shape in the sky that humanity has always been able to see (so long as we've lived in the northern hemisphere), and one day, assuming we still grace this planet in 100,000 years, it will no longer resemble the hunter the Greeks imagined. But then, billions of years hence, all the stars will have realigned, the Milky Way will have combined with andromeda. And beyond even that, the energy will so diminish that the bonds of the atoms will release. This too shall pass.

sixdimensional 11 years ago | | |

I agree with you.

I have found that the beauty of the temporary nature of everything (especially when considered in enormous time scales) highlights the beauty of the here and now.. and the need to enjoy it. In fact, while some say not to think of the future and stay in the present, sometimes I find that imagining far into the future is precisely what brings me back to the importance of and focus on the present.

Also, there's a feeling of pure awe I get when trying to imagine the unimaginable scale of the future (for us at least). It's a specific sensation.. I am not even sure awe is the right word to describe it.

amoruso 11 years ago |

This article reminded me of something I read a few years ago. What is it like to be really near a supernova? It's a quick read and entertaining too.

Life (Briefly) Near a Supernova:

http://www.nagt.org/files/nagt/jge/abstracts/Dutch_v53n1.pdf

dghf 11 years ago |

Any risk of a gamma-ray burst affecting Earth?

Lewton 11 years ago | |

Every second of every day :)

Filligree 11 years ago | |

Not from a supernova. Gamma-ray bursts are a wholly different phenomenon.

smeyer 11 years ago | | |

Not all supernovae have a GRB and not all GRBs have a supernova, but most long burst GRBs are thought to be from a supernova, no? I've been out of supernova research for a few years now, but that's what I recall.

IndianAstronaut 11 years ago | |

In the long term, this is always a possibility. Which is why for the future survival of our species, we must venture outside our solar system. Likely even outside our stellar neighborhood.

kijin 11 years ago |

Other than slightly brighter-than-normal nights, will there be any adverse effects on Earth?

The wikipedia article on near-Earth supernovae [1] suggests that Betelgeuse will be pretty safe because of its distance. But exactly how safe? What about all the delicate electronics that we've sent up to space? I suppose anything that can withstand a daily dose of solar radiation would probably be okay, but are there any specific wavelengths that could cause an issue?

[1] https://en.wikipedia.org/wiki/Near-Earth_supernova

ChuckMcM 11 years ago | |

Probably not unless you consider a group of self proclaimed holy men trying to follow it :-)

That said if you had some instruments closer to the heliopause you would definitely be able to detect the shock wave at that distance. It would be faint but should be well above the noise level of other particles.

aruggirello 11 years ago | |

Actually, a supernova would look like an impossibly tiny point source, much smaller than even your average laser pointer. I'm pretty sure the consequences of this haven't been thoroughly explored yet.

I'm not sure the Betelgeuse supernova, at a brightness around that of the full moon, would ignite fires, but I certainly wouldn't want to gaze at it with naked eyes, even at that brightness. IMHO such a light, given sufficient strength, could permanently damage the retina in your eyes.

avian 11 years ago | | |

I doubt it. Even without knowing exact surface power density that can cause damage to retina, the magnitudes discussed here sound far from dangerous.

You should know that even an impossibly tiny point source will get projected to a spot of finite size on the retina. The eye is not perfect - there is always some optical aberration. Plus, since we're talking about a star, there's also atmospheric distortion to think about.

The chances of light from Betelgeuse igniting a fire are very much zero. We're talking about light intensity about 10x lower than moonlight.

ksmiley 11 years ago | | |

Your reasoning reminds me of the danger of retinal damage when observing a solar eclipse - a human's natural inclination to not stare at the sun is sharply reduced because the viewable area is so much smaller than usual. Looking at a thin slice of the sun is as dangerous as looking at the unobscured sun, even if it doesn't feel like it. But I don't think Betelgeuse would be dangerous in this way. It would be more like watching a lunar eclipse, which may be done without safety equipment.

TazeTSchnitzel 11 years ago |

When I read that title, I assumed it had something to do with Douglas Adams.

lotsofmangos 11 years ago | |

You are maybe thinking of the Great Collapsing Hrung Disaster that wiped out all the old Praxibetel communities on Betelgeuse Seven.

shrikrishna 11 years ago |

Starts-With-A-Bang is a must-follow blog collection for anyone mildly interested in Physics. They're all frequent, up to date, and most importantly, accurate.

mkramlich 11 years ago |

semi-related: Betty From Betelgeuse is the name of one of the main characters in my book series The Dread Space Pirate Richard.

I chose Betelgeuse partly as a nod to HHGG and partly for the way it read and sounded when pronounced aloud. I think of all the star names it is possibly the most beautiful and memorable.

robinhoodexe 11 years ago |

I'm pretty sure Ford Prefect would be rather disappointed that his home planet got blown up...

yourad_io 11 years ago | |

Don't worry, he won't know for about 600 years. And they can always construct a new one.

cgtyoder 11 years ago |

All that said, Betelgeuse isn’t expected to explode for another 100,000 years or so.

Total click bait title.