[HN Gopher] How A Supernova Explodes (1985) [pdf]
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How A Supernova Explodes (1985) [pdf]
Author : rwmj
Score : 61 points
Date : 2023-06-16 20:55 UTC (1 days ago)
(HTM) web link (astro.uconn.edu)
(TXT) w3m dump (astro.uconn.edu)
| pixel_tracing wrote:
| Fun fact: Betelgeuse has been predicted to go supernova in our
| lifetimes. There is usually a live stream on YouTube you can
| observe of Betelgeuse
| throwbadubadu wrote:
| What is the real one? Too many "happening now" :/
| kristianc wrote:
| The problem is that it could also happen at any time in the
| next 10,000 to 100,000 years.
| irrational wrote:
| But, it could also happen tomorrow! I do hope it happens
| tomorrow, because that would be so cool.
| Sharlin wrote:
| That's not a very accurate way of saying "it could go supernova
| anytime in the next 100,000 years" meaning that it almost
| certainly won't go during our lifetimes. Unless we'll live for
| a long time which of course is not entirely out of the
| question.
|
| Also, I'm pretty sure there's no non-fake live stream of
| Betelgeuse on Youtube because it would require several robotic
| telescopes around the world programmed to coordinate and stream
| from wherever it's a) night and b) Betelgeuse in the sky.
| shagie wrote:
| https://en.wikipedia.org/wiki/Betelgeuse#Media_reporting
|
| > Due to misunderstandings caused by the 2009 publication of
| the star's 15% contraction, apparently of its outer atmosphere,
| Betelgeuse has frequently been the subject of scare stories and
| rumors suggesting that it will explode within a year, and
| leading to exaggerated claims about the consequences of such an
| event. The timing and prevalence of these rumors have been
| linked to broader misconceptions of astronomy, particularly to
| doomsday predictions relating to the Mayan calendrical
| apocalypse. Betelgeuse is not likely to produce a gamma-ray
| burst and is not close enough for its X-rays, ultraviolet
| radiation, or ejected material to cause significant effects on
| Earth.
|
| > Following the dimming of Betelgeuse in December 2019, reports
| appeared in the science and mainstream media that again
| included speculation that the star might be about to explode as
| a supernova - even in the face of scientific research that a
| supernova is not expected for perhaps 100,000 years. Some
| outlets reported the magnitude as faint as +1.3 as an unusual
| and interesting phenomenon, like Astronomy magazine, the
| National Geographic, and the Smithsonian.
|
| > Phil Plait, in his Bad Astronomy blog, noting that
| Betelgeuse's recent behaviour, "[w]hile unusual . . . isn't
| unprecedented," argued that the star is not likely to explode
| "for a long, long time." Dennis Overbye of The New York Times
| agreed that an explosion was not imminent but added that
| "astronomers are having fun thinking about it.
|
| ---
|
| Evolutionary tracks for Betelgeuse
| https://arxiv.org/abs/1406.3143v2
|
| > The best-fit MESA model left the main sequence about 10e6
| yrs. ago, while for the EG model it was only about 3 x 10e5
| years ago. Both models reached the base of the RGB about 40,000
| years ago. We followed the star through the final ex- haustion
| of core helium burning in both codes, followed by brief epochs
| of core-carbon, neon, oxygen and silicon burning until core
| collapse and super-nova an age of 8.5 Myr since the ZAMS for
| the MESA code. Our best guess is that the star will supernova
| in less than ~ 100, 000 yrs (even longer in the EG model). We
| note, however, that there error ellipse encompasses the entire
| track so that the star could be further along in its evolution.
| The constraint that it has passed the first dredge-up, however,
| means that the star is ascending the RSG phase. Our result is
| based upon mass loss from the base of the RGB is therefore a
| lower limit to how far it has evolved as a RSG.
| OldGuyInTheClub wrote:
| Repeating this recommendation from a recent comment thread
| involving the Bethe/Brown article[0].
|
| Youtuber "But Why?" has a very nicely animated explanation of the
| current state of affairs of core-collapse supernovae at
| https://www.youtube.com/watch?v=Yt-SBT7nNfU
|
| [0] Comment section of
| https://news.ycombinator.com/item?id=36362770
| ramraj07 wrote:
| Thanks, always on the lookout for new supernova YouTube videos,
| which surprisingly there are very few of which explain actual
| details as opposed to the drivel that is kurzgesagt. Many of
| these Popsci videos are even straight out wrong, they'll say
| crap like the core produces one neutrino per proton - like the
| math doesn't even add up dudes. Your video finally explains why
| there's so many neutrinos produced.
|
| Your video perfectly complements the two others I love. I'd say
| the perfect watching order would be to first see the general
| supernova discussion by launch pad astronomy[1], followed by
| your suggestion, then the "how to build a black hole" by pbs
| space time [2].
|
| 1. https://youtu.be/RZkR9zdUv-E
|
| 2. https://youtu.be/xx4562gesw0
| OldGuyInTheClub wrote:
| I enjoy Launch Pad's detailed look at things, as well. But, I
| also like Kurzgesagt. There's something about the pacing and
| editing of PBS videos that I find hard to watch for long
| periods of time. No qualms about the content, it seems like
| they edit out all the pauses.
| ramraj07 wrote:
| I'm not a fan of Kurzgesagt at all unfortunately. I'm not a
| physicist so I'll say maybe there's some justification that
| I don't fathom that explains why their fundamental
| explanation of the science is so terrible.
|
| But I am a biologist and I can assure you a good load of
| videos they make on it are at best not great explanations
| or at worst fundamentally unsubstantiated drivel. Like
| their latest one about how your body "kills cancers every
| day". I went through their massive google doc "evidence"
| and as suspected not a single real reference to any proof
| that this is true. It COULD be true, but it's not proven.
| I'm not even sure the evidence we have is actually pointing
| towards this direction. If it's true that your immune
| system clears cancers every day, then immunosuppression
| should instantly plunge you into cancer. Does it? Not
| really. May be some blood cancers but that's it.
|
| Point is, they show shiny videos explaining almost
| plausible sounding scientific concepts. But often it's
| still michio kaku level sensationalism. I personally
| believe this disingenuousness is the root cause of
| degradation in trust in science. The average person does
| have the ability to sniff bullshit and it eventually
| catches up to them in their mind that these scientists have
| no idea what they're talking about (like my observation
| that these videos say there's one neutron per proton in a
| supernova; I could instantly smell something rotten).
| Eliezer wrote:
| I miss reading things like this.
| moffkalast wrote:
| I miss having the patience to read things like this too.
| guender wrote:
| [dead]
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