The Big Star That Couldn't Become a Supernova

Supernova

Sosonova ⊗

Almostnova ⊗

Kindanova⊗

Awwwgoodforitfortryingnova ⊗

Mediocrenova √

Chevy Nova...

One of their prototypes

Hmm. Not what I would expect 'thermobaric' to look like.

Me neither. Thermobaric devices are detonated outside the target to maximise overpressure (hence the 'baric' part). This was detonated inside the vehicle. Were this an FAE, that would screw up the fuel-air mix and reduce its efficacy. No, this video is mistitled.

Was that a Takata air bag?

Boy isn't that company is Schitt Creek without a paddle, yes! Shigehisa-san's unofficial name is now 'General Recall.'

.....and that is all that really matters, isn't it? ...Your ('anonymous') belief that some lives were saved by your product.

.

I wonder how many more lives would have been saved (or alternately how many fewer would have been lost) had 'your' product operated as planned/expected.

This is pretty weird. Maybe it supernovas after it's a black hole and blasts in instead of out!

Type II supernova cores collapse - a process which literally takes a few seconds - leaving a vacancy behind into which the star's outer layers fall. In 'ordinary' supernovae the shells fall inward and rebound off the shrunken (now neutron star if it's not massive enough) core. In this case the core probably went straight into a black hole and the infalling layers didn't have anything against which to collide. They went straight down the drain. It's the rebound that makes it go supernova. No rebound, no bang. In very massive stars the core is quite large and the final phase where it's fused into iron/nickel can take place throughout a large volume in a matter of minutes. Once it does, all bets are off. It's history and, because it's so massive, it won't stop at the 'neutron-star' phase. That core will go straight into a black hole and everything falling in after it will too. Poof!

These were predicted theoretically some time ago but they've never been seen before. The article gives one a sense that it's a new idea, but it's actually not. There are probably photographic records of other such collapses that have thus far gone unnoticed (it's a bit tough manually looking at thousands of photographic plates, each containing thousands of stars, and notice one star is missing between plates several years apart). Recent advances in automatic comparison of archived images will greatly help in finding others if they've been recorded.

From the viewpoint of an observer falling into the black hole, it may take seconds or minutes. From our viewpoint, time slows down close to the black hole and actually comes to a stop at the event horizon. So we will never see matter falling through the event horizon, sort of an astronomical version of Zeno's paradox.

"To a distant observer, clocks near a black hole appear to tick more slowly than those further away from the black hole.^[54] Due to this effect, known as gravitational time dilation, an object falling into a black hole appears to slow as it approaches the event horizon, taking an infinite time to reach it.^[55] At the same time, all processes on this object slow down, from the view point of a fixed outside observer, causing any light emitted by the object to appear redder and dimmer, an effect known as gravitational redshift.^[56] Eventually, the falling object

becomes so dim that it can no longer be seen.

On the other hand, indestructible observers falling into a black hole do not notice any of these effects as they cross the event horizon. According to their own clocks, which appear to them to tick normally, they cross the event horizon after a finite time without noting any singular behaviour; it is impossible to determine the location of the event horizon from local observations."

https://en.wikipedia.org/wiki/Black_hole

Yes, absolutely, though we need to keep in mind that gravitational time dilation diminishes very quickly with distance. For example, for a non-rotating BH, its effect has already diminished to 50% at only 1 1/3 Schwarzchild radii; to 1% at about 50.3 radii. In the case of this star the 1% mark is around 1840 km (again, for a non-rotating case). The progenitor star was a red supergiant roughly the size of Jupiter's orbit. As significant time dilation takes place in only a relatively microscopic region compared to the star overall, the collapse would have proceeded apace as seen from an observer relatively nearby (say, from Neptune's distance).

It's kind of weird to think about, but the contents of the star are still falling toward the event horizon (in our time frame) and will be forever.

If you were falling toward the event horizon and you could still communicate, in a matter of seconds or minutes (of your time) the universe would age, hundreds, thousands, millions... of years. When you reached the event horizon (in seconds or minutes of your time), infinite time would have elapsed on the outside.

It boggles the mind...

Yes! As that 'gamma-ray-hot' material falls in I wonder how much of its emissions are due to gravitational redshift and how much due to the outer atmosphere that was blown off. Currently the aggregate emits about 5000 times as much IR as our Sun. It would interesting to see how bright it is at microwave frequencies.

I wonder if there are collapses where the core mass by itself would be insufficient to collapse into a black hole, but the in-falling and bouncing material squeezes the core sufficiently to raise the density to the point where it collapses into a black hole.

If so, some boundary within the central mass would cross the density threshold to become light retentive. Any mass remaining outside that boundary would then fall in and generate a whopping radiation burst indistinguishable from a supernova.

The case I would anticipate would result in a whimper black hole formation would be when the mass of the star is at or very slightly more massive than the minimum mass to form an event horizon. In that case, the radiation from the collapse is inside the event horizon and there is little mass outside the boundary to generate a gamma burst as it falls into the formed event horizon.

I suppose someone in the astrophysics community is doing collapse rate/pressure/ density and shock wave analysis similar to the plutonium bomb implosion studies to see what variety of black hole formation scenarios come up.

Well there are two kinds of stars. Some stars blow. Other stars suck. It's like high school.

Lol! GA

On that note, we have black holes due to gravity, but GR also predicts white holes. Would those be due to levity?

The star, which was 25 times as massive as our sun, should have exploded in a very bright supernova. Instead, it fizzled out -- and then left behind a black hole. ..... As many as 30 percent of such stars, it seems, may quietly collapse into black holes -- no supernova required.

Things change since I was in school... I was taught for a star to go Super Nova it had to be eight to 15 solar masses.

And for a star to go nova it had to be 1.5....? solar mass.

All this time,... I've have been told, I was living a lie. , I guess that stars this size only has the potential to go nova or super nova.

When I was in school stars were so much simpler. Much has been discovered since then.

so your saying ignorance is bliss?...

No, I prefer the Red Pill actually - along with a good Margarita.

Depend perhaps on energy content/material content.