I just read about this red giant exploding:
and was wondering in terms of human time scale, how fast does this occur? Is it something that happens within seconds, or does it take days to blow up…or a few weeks…or perhaps hundreds of years?
The story implies that the death was capture with photographs, indicating relatively instant explosion, but doesn’t give a clear time frame.
Reading this: Supernova - Wikipedia suggests that it happens within a few seconds and most of the energy comes out as neutrinos. But it takes a couple weeks to reach peak luminosity.
NASA has a chart that shows the peak brightness of the event. It’s notable that the x-axis is labeled in days, while the “shock breakout” is measured in minutes.
The article where the chart comes from discusses a similar explosion viewed earlier.
Depends on the sort of death. If they’re above a certain mass, they go supernova and depending on their mass, either end up a neutron star if they’re on the smaller side, or a black hole on the larger side. This happens pretty quickly- a fraction of a second for the core to collapse, a few hours for the shockwave to reach the outside of the star, and a few months of actual energy release.
Less massive stars go to being a red giant, and eventually blow out their outer layers into a planetary nebula- this can take thousands of years, leaving a white dwarf at the end of the process. While this is a long time in human terms, it’s a blink of an eye in stellar terms, considering that yellow dwarfs like our sun live for 10 billion years, more or less.
http://oneminuteastronomer.com/10001/red-giants-planetary-nebulae/
So the nebula in the OP’s article is probably thousands of years old.
Curious, I looked up some supernova simulations on youtube.
This one simulates half a second. And this one simulates a whopping 1.7 seconds (had to look it up on arxiv to get the timing, since it wasn’t readable in the video).
I don’t think any human can intuitively understand that kind of speed, size, and energy release.
Those various graphs that show brightness increasing for days may well be valid descriptions of how the energy flow looks over that timeline.
But if you’re nearby, like on a planet orbiting that star, the energy release trashes your planet real early in the process. From your POV the experience may take just a few seconds even though the ongoing explosion is still growing in intensity a few days later.
Note: this is a red giant blasting itself apart. Not a supernova.
The Wikipedia page on the nebula gives more info.
In particular its radius 0.7 light years which right away says this isn’t happening in days. The earliest cite in the article is from 1989. If you take the info from “his material, shown as yellow in the image, is zooming away at speeds up to one and a half million kilometers per hour.” and do some Math you get a ridiculous answer. Oh well.
Quick Googling turns up no age estimate of the nebula. It is expected to turn into a typical planetary nebula in 10000 years, give or take. And 10000 years is a blink of an eye.
