Why is a nearby supernove (far) overdue?

[Denis12]

For more than hundreds of years there has no supernova recorded in our neighborhood within (a few 1000) lightyears. till now still nothing will happen. I hope it will happen (very) soon. The crab nebulae M1 was the last supernova in our neighborhood ,and that was in the 14 or the fifteenth century or so ,and that is (far) too long ago. I am still waiting (impatient) for the next spectaculair supernova explosion. I am sure that it will happen within ten or 30 years. And the (possible) supernova in the (far) distant galaxy in the constellation Aries has of course not my interest ,because you can see nothing of it,only if you have a telescope that can see things at the 18th magnitude. Maybe you have such a telescope? I dont have it. Yes a supernova that is in our neighborhood ,that has my great interest. When you can see it by daylight ,and when it shines here at night as bright ,such as the suns magnitude on pluto. Yes THAT!! is what i am waiting for. Not a supernova in a far distant galaxy that is not visible with the naked eye and not even with your and (my) backyard telescope. The only thing is,forget that distant galaxy with the (possible) explosion that is invisible with backyard telescopes and the naked eye. What do you think about my story? Thanks. Denis12.

[antoniseb]

Hi Denis12,

There have probably been several supernovae in our galaxy in the last four hundred years, but they have all been hidden behind dust clouds. It is relatively unlikely that there will be one within 1000 lightyears in the next 30 years, just because there are no candidates that nearby. There could be some in the galaxy, but not nearby.

[snabald]

Hi Denis12,

There have probably been several supernovae in our galaxy in the last four hundred years, but they have all been hidden behind dust clouds. It is relatively unlikely that there will be one within 1000 lightyears in the next 30 years, just because there are no candidates that nearby. There could be some in the galaxy, but not nearby.

What about Betelgeuse?

[The Saint]

Maybe a supernova is already under way according to the usually unreliable Sorcha Faal!
http://www.whatdoesitmean.com/index881.htm

[agingjb]

A very quick look at Wikipedia gives recent (Milky Way) supernovae years and estimated distances in light years: 1006 (7,000), 1054 (6,500), 1181 (10,000), 1572 (10,000), 1604 (20,000).

Although I suppose there is a very superficial sort of clustering there, supernovae timings (and visibility from Earth) are surely random.

[Kaptain K]

1) The Crab Nebula supernova was seen in 1054 A.D.
2) The last two supernovae in ou galaxy that were visible from Earth were Tycho's supernova seen in 1572 and Kepler's supernova in 1604.

edit - dang, beat me to it.

[Denis12]

Hi Denis12,

There have probably been several supernovae in our galaxy in the last four hundred years, but they have all been hidden behind dust clouds. It is relatively unlikely that there will be one within 1000 lightyears in the next 30 years, just because there are no candidates that nearby. There could be some in the galaxy, but not nearby.

No candidates nearby?? What do you think of Betelgeuse,Antares and spica? All red and white supergiants within 1000 lightyears they will go supernova within years. Can you react please? Thank you.

[antoniseb]

In the next thirty years (your limitation) the only stars that seem relatively close and are candidates for supernovae in my understanding are Rho Cass and Eta Carina. Neither of these are within 1000 light years. I suspect that most WR stars are also candidates, but I don't fully understand WR stars.

Please keep in mind that I am merely parroting what I have read elsewhere, and my opinion about this is not that of some post-doc in supernova precursor stars.

[The Saint]

If Alpha Centauri going supernova at 4 ly would end life on Earth, just how many lys are considered far enough for us to be safe from the damaging effects of even the biggest supernova? 50 ly?

[cjl]

In the next thirty years (your limitation) the only stars that seem relatively close and are candidates for supernovae in my understanding are Rho Cass and Eta Carina. Neither of these are within 1000 light years. I suspect that most WR stars are also candidates, but I don't fully understand WR stars.

Please keep in mind that I am merely parroting what I have read elsewhere, and my opinion about this is not that of some post-doc in supernova precursor stars.

I still don't see why you don't include Betelgeuse or Antares in that. Both of those could easily go in the next month (or the next thousand years - it is impossible to tell).

[Vaelroth]

No candidates nearby?? What do you think of Betelgeuse,Antares and spica? All red and white supergiants within 1000 lightyears they will go supernova within years. Can you react please? Thank you.

I think I read somewhere that there were speculations that Betelgeuse has already gone supernova and that we just haven't seen it yet. Interesting hypothesis, but I doubt its credibility as it was just an offhand article.

(There is your local supernova OPer.)

[Romanus]

I think it's unlikely that we'll see any supernova within 1000 light years within the lifetime of the human race. Yes, I'm making that a blanket statement. It's not enough for a star to just have the mass to go supernova, but also:

1.) The star has to, obviously, be within 1000 ly of Earth, and there are few stars that fit the bill within that range.

2.) They have to be at *exactly* the right point in their evolutionary history. The final stages before a massive star explodes can take place in as little as a year, and this is out of the several-million year lifespan of the star.

That all of the observed bright SN have been far away argues strongly, IMO, that the next one will be similarly distant, like the aforementioned Eta Carinae or Rho Cas. I'm guessing a SN as close as Betelgeuse or Antares happens maybe a few times per million years, so I'm not holding my breath for those--though Lord knows that I'd be glad to be wrong. I can't imagine a more spectacular sight.

[Denis12]

I think I read somewhere that there were speculations that Betelgeuse has already gone supernova and that we just haven't seen it yet. Interesting hypothesis, but I doubt its credibility as it was just an offhand article.

(There is your local supernova OPer.)

What do they mean with that Betelgeuse has already gone supernova and that we haven't seen it yet? Can you explain that Vaelroth? Thanks.

[Vaelroth]

I would think that one would be obvious to someone posting on an astronomy site.

It is possible that Betelgeuse has already gone supernova, but because light actually has a velocity and it takes time to move over large distances we might night be able to see that Betelgeuse has gone supernova until a hundered years from now, or longer.

If Betelgeuse were to go supernova right now, we wouldn't be able to see that it had gone supernova until 430 years from now because of the distance that light must travel from one star to another.

[Denis12]

How will Betelgeuse appear shortly before (1 year) or 1 month or a couple of days the supernova explosion? gives the star signals short before the explosion? And my last question ,what happens with the earth if we are at 1 lightyear distance away from Betelgeuse and it goes a supernova at 1 lightyear away? I wish that we can experience a supernova explosion at 1 lightyear distance ,or am i crazy.

[Vaelroth]

I don't know what the star would look like to our modern sensory equipment before the explosion as I'm here to learn mostly. However, I do know that we'd feel the effects of a supernova from one of the Centauri stars and they are 4.5 ly away. I figure that a supernova frome 1 ly would be pretty devastating to our solar system.

[jkmccrann]

How will Betelgeuse appear shortly before (1 year) or 1 month or a couple of days the supernova explosion? gives the star signals short before the explosion? And my last question ,what happens with the earth if we are at 1 lightyear distance away from Betelgeuse and it goes a supernova at 1 lightyear away? I wish that we can experience a supernova explosion at 1 lightyear distance ,or am i crazy.

If I read you correctly and you're wishing for there to be a supernova at a distance of 1ly, then yes, you are crazy - because that would likely presage a mass extinction event here on Earth and I can assure you - you won't really enjoy that very much. Be glad that Betelgeuse is 430ly away, rather than 4.3ly.

[Kaptain K]

How will Betelgeuse appear shortly before (1 year) or 1 month or a couple of days the supernova explosion?

As far as we know, it will look exactly as it does now. A supergiant star like Betegeuse has already made the transition from main sequence (hydrogen fusion) to helium (and heavier element) fusion. Fusion takes place in the core, which in the case of supergiants lies hundreds of millions of kilometers beneath the surface. Gradually (in human terms) an iron core builds up at the center of the core. At some point, the iron core reaches a point where electron degeneracy can no longer support it against gravity. In milliseconds it collapses to a neutron star. The rest of the infalling core bounces off the neutron star and the shock wave races through the outer layers. It may take a day or so for the shock wave to reach the surface, but there will be no visible signs until the surface explodes into a flash of light.

[antoniseb]

As far as we know, it will look exactly as it does now.

I'm curious to know if this is an educated opinion. I do not know much about precursors to Supernovae. Aside from Sanduleak 69+202, I don't know if we have much first hand knowledge of such things. I guess there has been a Red Giant or two in M101 that we have some limited knowledge of.

Betelgeuse is about 15 solar masses, which puts it at the low end of the mass range of stars that might become supernovae. It is currently changing its brightness somewhat chaotically over a factor of about 3. I presume it is turning Helium into Carbon and Oxygen, but that it isn't massive enough to be a WR star during this process. How long does a star go through this stage? I presume that a relative light-weight like Betelgeuse can do this for millions of years before starting to turn Carbon into Silicon & Magnesium.

So yes, for all we know Betelgeuse could have exploded in the last 430 years, and the wave of intense light and radiation could be headed our way right now, but I think the chances are low.

[Denis12]

Some supernovas become a neutronstar and there are also supernovas that become a black hole. What kind of stars that exploded as a supernova are becoming a black hole?

[Saluki]

I would think that one would be obvious to someone posting on an astronomy site.

It is possible that Betelgeuse has already gone supernova, but because light actually has a velocity and it takes time to move over large distances we might night be able to see that Betelgeuse has gone supernova until a hundered years from now, or longer.

If Betelgeuse were to go supernova right now, we wouldn't be able to see that it had gone supernova until 430 years from now because of the distance that light must travel from one star to another.

You are implying that simultaneity is independent of reference frame. From our frame, the star goes supernova when we are able to observe it go supernova.

[Hamlet]

Some supernovas become a neutronstar and there are also supernovas that become a black hole. What kind of stars that exploded as a supernova are becoming a black hole?

It depends on the mass of the remnant core that is left over after the supernova explosion. If the remnant mass falls betwenn 1.44 and 3 solar masses, a neutron star forms. If the remnant mass is greater than 3 solar masses, the core forms into a black hole.

A core of a neutron star is made up of what is called degenerate matter. Matter in this state creates pressure that resists further collapse due to gravity. For a core that is greater than 3 solar masses, the degeneracy pressure can no longer resist gravity and the core collapses to a black hole.

I basically all boils down to mass.

[George]

Again mentioning Eta Carinae , it has already "blown" to supernova, or near supernova, brightness.

In 1843, Eta Carinae had a "Great Eruption," when it brightened to outshine every star in Earth's night sky except for Sirius, reaching a maximum magnitude of -0.8...

What about all the Type Ia candidates? Are there many, and are they well known?

[Vaelroth]

You are implying that simultaneity is independent of reference frame. From our frame, the star goes supernova when we are able to observe it go supernova.

I prefer the concept of an omniscient reference point to the idea of a localized reference point in astrological matters.

[Denis12]

Again mentioning Eta Carinae , it has already "blown" to supernova, or near supernova, brightness.



What about all the Type Ia candidates? Are there many, and are they well known?

Eta Carinae already blown as supernova?? No of course not ,then it has been much much shine brighter and the star still exists after this sort of explosion. What kind of star is Eta Carinae? I think that Eta Carinae will be one of the first coming supernovas in the (near) future. I hope it of course.

[George]

Stars can blow off shells of gas, creating planetary nebula. Eta Carinae only recently has done this major blast which is expanding outward. If you go to the link it will show you what 163 years of expansion of this sort of blast looks like. It is unlikely it will be going supernova soon.

[Tim Thompson]

See the webpage: Will a Nearby Supernova Endanger Life on Earth? (last updated 8 Apr 2005). Looks like anything closer than 1000 parsecs is potentially lethal; the closer it gets, the more lethal. Put it at 4.3 LY, and you can kiss yourself goodbye.

[antoniseb]

An interesting thought about this is would a nearby Supernova briefly melt Mars' oceans and ice caps and cause massive resurfacing weather on the planet?

[RealTalk]

What do they mean with that Betelgeuse has already gone supernova and that we haven't seen it yet? Can you explain that Vaelroth? Thanks.

If Betelgeuse went supernova 200 years ago, the light from the supernova wont reach here for another 227 years, since Betelgeuse is 427 lightyears away.

[TriangleMan]

I've always wondered if Sirius B was a candidate for TypeIa supernova. It is a white dwarf of about 1.0 solar mass but 20AU away from Sirius. If it leeches enough matter from Sirius (another 0.4 solar masses) wouldn't it reach the Chandrasekhar limit? Of course, I think getting up to the limit would take a long time, but a Sirius B supernova would definately kill all life on Earth.