This one has bad audio, please watch the revised and updated version of this video here: ua-cam.com/play/PLyu4Fovbph6d9PJ25kXjmEDSAXQp76Mpl.html WHOOPS LIST! 1) Be sure to plug your ears at @24:49 for the bad audio super-nova 2) I made a bungle in speaking. Neither nickel-58 nor nickel-62 are radioactive. Nickel-58 actually makes up 68% of nickel.
Keep going, it's all good. Observe first then research what you see. If you get confused at times you're progressing, closer to the truth and a defining moment.
Wow .. When I really want to know how dumb I am .. I watch videos like this . It is amazing what smart men and women have discovered throughout the years .. My father was one of these super intelligent types that tried to get me interested and curious throughout the years .. Even in his last week of life .. He loved to study and talk about quantum physics .. He passed at 87 with an alive mind
It takes a special kind of mind to pour ones life into research and discoveries of this calibur. Hell, my dad made the first Bradley and MLRS fighting vehicles for the armed forces, and here I sit a humble diesel mechanic. We can't all fill the massive shoes left for us by our fathers. Don't beat yourself up too much. You're probably smarter than most folks you know!
Wow, the NRC graph on how Iron is the boundary between fusion and fission is a no brainer to me now that I see the graph. Very cool. Iron has the tightest bonds. I've know for years that Stars could not fuse elements larger than Fe but now I know in the gut why.
I took the statement to mean the most abundant heavy element produced by nucleosynthesis...much\most of the H & He predate stars...I guess I don't think of O, C, N & even Si as "heavy" elements...I suppose it matters what you are comparing them to
I absolutely loved your content.....had i been born in the US or any European countries, I definitely would have been an astronomer.....I live vicariously through you and absolutely loved every minute of it....
30:00: The bright comet at the bottom of the picture is C/2006 P1 (McNaught), also known as the Great Comet of 2007. Links: apod.nasa.gov/apod/ap070330.html and en.wikipedia.org/wiki/C/2006_P1
I don't know why, but your approach to teaching this clicks for me so much better than many other channels, even ones with far flashier presentation or sexier narrators. (Come on, everyone loves the buttery smooth voice of some random British bloke with no real physics training or education degree.) It's just arranged in a way and presented with aids that works for my brain. Wish I had access to this 20 years ago... Might have chosen a very different life path if I knew I could actually retain this stuff.
I love your video's and I love to watch the night sky on a dark spot, the reason that I love your vidoes is that you involve enough physics to keep me interested, without getting too complicated for my background knowledge from school.
Great lecture! However, I would like to comment on two nickel isotopes mentioned at 11:01: Both nickel-58 and nickel-62 are actually stable. More precisely, nickel-58 is observationally stable ("believed to decay by β+β+ to iron-58 with a half-life over 7×10^20 years"). From: en.wikipedia.org/wiki/Isotopes_of_nickel
Thanks for sharing ... just found your lecture after reading Oppenheimer & Snyder, your lecture helped appreciate the context ... (That was: On Continued Gravitational Contraction, J. R. Oppenheimer and H. Snyder - Phys. Rev. 56, 455 - Published 1 September 1939)
About the info at 36:27, for some extra context. Solar neutrino flux at earth distance is about 20 billion per second per square cm. The SN1987A, produced double or triple of that (for about 10 seconds), while being 11 billion times further away from earth than the sun. And you need to also know that surface area scales with square of distance, not linear. So it was maybe thousand billions of billions of times higher at 1AU distance from the core. Core collapse supernovae are fascinating.
You just got another subscriber. AWESOME video! (Except for "iron 56 is the most common element in the universe", that triggered me lol (read further down you corrected it)). You just clarified so many things that other sources refuse to go in depth on, like WHY exactly Iron is so detrimental to a star's support. This is the first time fusion vs fission was explained this way and its just so awesome to understand it like this now. Thank you!
Cool videos. Really informative. 99% of the supernova energy is packed into neutrinos? Well, it's a quite effective way to get rid of all the energy of the star's core. It is fascinating that these dramatic processes in nature are almost undetectable and unvisible. All the light drom the supernova is just a small shadow compared to the almost unvisible neutrino outburst.
At 11:32 I think you misspoke. You said Iron 56 is the most common element in the universe. Not even close, unless you mean maybe by weight? Or you misspoke, or I heard you wrong. Which is possible, I've got one ear less sensitive than the other, so I sometimes hear things wrong.
The weird one out is actually He4. This nucleus is unusually stable and so pokes out above the curve. The "why" is hidden somewhere deep in the ugly-math of Quantum Chromodynamics, but there has been an empirical observation for a while that some nuclei have "magic numbers" of neutrons and protons that give them unusual stability. He4 is "doubly magic", as both it's neutron count and proton count rolled the magic snake-eyes.
Excellent presentation. I have a question: given the intensity of the big bang, why only hydrogen and helium? Why not more other stuff, like a supernova?
An impressive, detailed description of nuclear processes. Depending on how much use is to be made of it, apart from casual browsing, I think it would benefit from a little boiling down and tidying up. It sounds like a spontaneous illustrated talk and although it does a great job of enthusiastically imparting a lot of interesting information there is a fair bit of rapid fire repetition that had me clicking on the advance 10 s button. The wealth of content might be communicated a little more effectively with fewer words. All the same I found myself learning new things and understanding previously learned aspects of supernova more clearly than before, and have heard few utube presentations like it.
@@JasonKendallAstronomer I only discovered your lectures very recently and have been following some of them. Found them immensely informative with enough detail to keep non experts like me interested but not bogged down by heavy maths. Amongs the best introductory astronomy I have so far come across on the web.
There are many ways. Most common fusion and fission actions are... proton capture, alpha particle capture, beta decay and capture. There are many others, but these are the basics. Neutron capture, too. As they build in various paths, some are energetically favored than others, so the most common reactions and the “easiest” win the day.
10^48 Joules for the neutrino burst energy output - may be an order of magnitude (or a few) too high? if correct, that would be something like 6 times total mass-energy of the Sun. In terms of luminosity, it's not just outshining the galaxy, but compares to the entire observable Universe.
Do you have any material of things such as pair instability supernovae, or is there anything like that in the works? Amazing video, it's difficult to find a video as comprehensive as this so thank you for uploading this.
Thanks for a wonderful video. I realize that the confirmation for this is more recent than the video, but the heaviest of elements are made from the merger of neutron stars, not super novae.
I’m guessing the iron core star has a rotation with a significant angular velocity. So can we expect that it would have an extremely strong magnetic field?
I was under the impression that past a certain pressure & temperature, iron/nickel would fuse into zinc, but at the cost of absorbing energy, thus accelerating the core collapse? Is this correct, or only for a certain mass range?
Zinc is definitely on the "bad side" of the Iron Mountain. Anything with an atomic mass greater than Fe/Ni will consume energy to be produced, and thus hasten the collapse.
Hi professor, a question about the core bounce: when the core contracts that fast is its angular momentum preserved, meaning a really fast spinning core before it bounces back?
That's very correct! That's why neutron stars spin so fast. I'm sure you've watched this: ua-cam.com/video/PIgllxJIbW8/v-deo.html. But I leave it here just in case...
Outstanding description of a supernova explosion.Just one question: any assumptions in the whole sequence that leads to the final state ( BH or neutron star, I believe ). No chance that the conservation of initial angular momentum could stop the continuous shrinking due to sort of balance between centrifugal force and gravity before reaching those two possible final states?
Thanks! Likely not. Remember that black holes are described by only three things: mass, rotational spin and electric charge. The last one is not known to matter at all in reality. The first is very important. But the second is also important and has been tested in the weak regime, with the Gravity Probe B experiment, modeling gravitational waves, and modeling the image seen by the Event Horizon Telescope. It doesn’t stop the collapse.
Given photon wandering taking a long time for fusion-created light to make it out of the core, once the heavier stages of burning start, is there any outward signs the burning mode has changed?
Why does eta carinae have blasts only on the poles and equator? A mag field strong enough to hold back an exploding star? www.pitt.edu/~cejones/GeoImages/0PlanetaryFormation/StarDeath/EtaCarinae.jpg
@@JasonKendallAstronomer Thanks ...becomes more interesting "in light" of the fact it's been officially entered into the wiki as being discovered only in 2021 but there is much information of scholars and professionals sending in research regarding the subject going back years. Of course they were met with great resistance and imho solar cycles should scale like everything else. I have become extremely fascinated with the spotlight of influence vs the occultations of science knowledge and this subject of solar micro bursts or the solar micro novae has been a fun one. You also have mainstream influencers out their saying we don't have much info/data on the sun. Your content has been quite an eclipse to the contrary! Thank you!
When they say that a neutrino will need a light year length of lead for it to have an even chance of getting absorbed.. does that apply to these high energy neutrinos?
I cover that lightly in my Gravitational Wave and Gamma Ray Burst sections. They are, of course, significant contributors, so I'll eventually have to make an addendum video. I'm mostly covering the fiducial introductory concepts of fusion.
en.wikipedia.org/wiki/Supernova_nucleosynthesis#/media/File:Nucleosynthesis_periodic_table.svg this shows typical expected sources as we currently know them.
@@JasonKendallAstronomer FYI I am an amateur astronomer and enjoy your posts. Question: any thought on the origin of supermassive black holes at the centers of most spiral galaxies?
Hi, Jason. I wanted to sign on to your website to watch your videos in order. However, your site is listed by Microsoft 10 as being "Not Secure", so I will just continue to enjoy your UA-cam Channel. I have read that this situation maybe propagated by large software security companies to push their products. It is hard very challenging to justify taking the risk when there has been so much foreign interference now though perfectly innocent sites. I am sorry, yet appreciate your generosity in using the YT platform for sharing your experience and this fascinating information with us!
Sherill, your trepidation is justified. I guess the era of owning and maintaining your own website is over. I'll have to look at alternatives for distributing my static content. In the meantime, to show I'm not a "bad actor", you can always look me up on my William Paterson University website. In fact, I may move the summary content there. Furthermore, I did notice a steep, rapid decline in viewers recently. Perhaps people wanted to learn, but found what you found. I'll look into it. Likely, though, I'll be forced to use a more standard web hosting provider, that costs more, and gives me less....
As best I can determine, the only elements heavier than iron that are involved in life are: cobalt, copper, zinc, selenium, molybdenum, and iodine. Most of these are in tiny quantities, raising the question of whether life truly requires them, or if they're more of a matter of convenience, with functions that could be provided by something else. Cobalt, the linchpin of vitamin B12, is one of those with very tiny quantities, but it seems to be ubiquitous throughout the biosphere. But I think it's natural to wonder if life could occur with no supernova to seed the environment with heavy elements.
what I would like to see is a graph showing the star's mass as it drops from the hydrogen envelope down to the iron core. As a percentage graph. I would think the lowest hydrogen compaction level would be a large part of the total mass of the star.
Probably a 'silly' question here, but i think it would be even MORE silly not to ask... I've learned that fusion produces energy only up to the iron/nickel level (I think of this as being akin to exothermic as net energy is RELEASED). Beyond the iron/nickel boundary, it no longer releases energy (which I think of as being akin to endothermic). We're constantly told that it all just STOPS at the iron/nickel level, but surely there is SOME degree of heavier elements produced? (Even though their production is a net DRAIN on total energy, I cannot help but think that they are 'occasionally' still produced, even if the actual probability is fairly low... Assuming they ARE produced at all, what would be the realistic percentages involved for Cu and other heavier elements? Below 1%??? Below 0.0000000000001%???? Perhaps any such 'heavier' elements produced have a higher probability of becoming 'fission' fuel at the immense temperatures involved and they are therefore annihilated almost immediately???? It'd be interesting for me to know...
This is a really good question. The environment in the core of a collapsing star becomes so dense and saturated with high-energy photons and neutrinos, that all the heavy elements that do exist are, in fact, annihilated. However, the momentary explosion also does produce some heavy elements through rapid-neutron-capture processes. These then decay down to more stable isotopes of the same or other elements. That's what the major part of the glow from a supernova remnant actually is, the fission decay or nucleonic decay (radioactive decay) of elements. So, yes they are created, but not directly in the core, but in the shockwaves outside the core. The core is likely pure neutrons, or pure quarks, depending on mass and composition prior to the supernova event.
@@JasonKendallAstronomer Thanks HEAPS for the response... I have one further question (if you have the time...) Imagine we're a day / week / month BEFORE core collapse begins in our hypothetical high-mass star. i.e. There's still enough outward pressure to remain in equilibrium with the inward pressure of gravity since the final stage(s) of fusion are still ongoing. Is there ANY probability at these SIGNIFICANTLY lower temperatures / pressures to create ANY of the 'heavier than iron / nickel' elements?0 (While the 'average' temp / pressure throughout the core might be insufficient, I cannot help but think that there could be 'hot spots' within which the local conditions ARE sufficient to support such production? I accept that it's quite feasible that any such elements may well be annihilated at a faster rate than they're produced leading to an overall population that tends towards zero)
@@JasonKendallAstronomer I don't mind the old videos, and will happily listen to new ones. Thanks very much for the public outreach education. This kind of thing is true to the spirit of the original hopes for the internet.
I think a temperature of 10bnK will correspond to around 1Mev rather than 10Mev. 10Mev would require around 100bnK perhaps... Does high density also play some role?
One this I do not understand. If the envelope is few AU, how it can all infall and rebounce in milliseconds? It takes dozens of minutes at the speed of light.
I cringe with some of those mistakes "Iron is the most common thing in the universe" Last I checked Hydrogen Helium Oxygen is way more Iron is in the top ten elements in our Universe but it isn't anywhere close to the most common. Also worth noting that Red giants can make small amounts of certain heavier elements via decay limited neutron capture chains and the really massive elements are now understood to come from far more exotic processes involving Neutron Stars. Either via Neutron Star collisions or the extremely rare destruction of a newly formed Neutron stars via "aborted" Supernovae called Collapsars. Normal Supernovae aren't extreme enough to get you Uranium since slow Neutron capture gets terminated at Bismuth. It is interesting to note there have apparently been several supernovae in our galaxy since Kepler saw SN1604 saw and SN1987A they were just invisible to use due to the intervening gas and dust (The "curse" of being inside our galaxy). Of course both were Type Ia supernovae resulting from white dwarf mergers and thus not core collapse so no Neutrinos would have been visible. The name separation between Type I and Type II supernovae based on hydrogen has the unfortunate consequence of separating the more massive classes of core collapse supernovae Type Ib and Type Ic from their less massive cousins since the reason they lack Hydrogen, or in the case of Type Ic Helium as well, is that their progenitor stars stellar winds were so strong they stripped away their Hydrogen and or Helium envelopes. These stars known as Wolf Raynet stars are a fascinating class of stars which depending on their mass and metallicity result in black holes or WNh are probably the most mind boggling of these as they are fully convective due to intense catalyzed nuclear reactions in their cores it is hard to fathom 100+ solar mass behemoths burning through nearly all of their hydrogen R136a1 being a crazy example with over 315 solar masses and having burned through 60% of its hydrogen. Of course it isn't even known if stars of that type even die in supernovae (as oppose to collapsing strait into a black hole) so I'm getting a bit off track. That said one of the more interesting discoveries from the combination of the geological records of the Earth and the Moon is that over the the interval of 20-2 million years The Earth had some close encounters with a number of nearby Supernovae the last of which exploded about 2 and a half million years ago a little over 400 light years away. Evidence comes in the form of short lived isotopes such as Iron 60 buried within sediments deposited around this time as well as our solar systems position within a large "local bubble" formed by the expanding shock waves of these supernovae and filled with under dense gas and dust radiating in X-Ray light. Currently our solar system is near the edge of this region and will "soon" leave the supernovae remnant but it seems we missed quite a light show. Of course there is some, still somewhat controversial but growing, evidence that suggests these supernovae probably played a role in altering climatic conditions on Earth. The most well supported of these effects currently is probably the deposition of energy into the Earth's atmosphere which at the distance suggested by tracking back trajectories it can be determined would be concentrated in the upper troposphere driving increased lightning frequency by lowering the critical threshold for storms to generate lightning strikes. This meshes well with evidence from the fossil record suggesting that over the last 20 million years fire frequency increased driving more fire based ecology in particular the rapid diversification of grasses and the establishment of the Earth's first grasslands. Yes Grass and thus grassland environments haven't existed until about 20 Ma with modern grasses only evolving about 30 million years ago and only becoming a significant component to Earth's flora in the last 20 million years prior to that you just had various types of forest environments. This change which seems to have been very important in our own evolution fits neatly with our close approach to a massive star forming region as our solar system passed through the local arm segment of our galaxy.
Yeah, I do need to do an edit of that video. I do these long one-offs. Now that they are getting a lot of attention, I need to revisit a couple of them.
you said brighter than 5 billion suns -- the text said one sun for 5 billion years. A little confusing --- perhaps a chart or Mev or Gev or something larger?
It never occurred to me to ask before... But does nuclear FISSION ever happen in a star? Just thinking that you've got these heavier elements later in stellar life under crazy pressure/heat, all kinds of particles flying around... Seems like it could happen? And I mean in a broad sense it's just like a symmetric process to fusion. I understand the basics of fission and realize you want less stable fuel, but it's also more favorable conditions energy -wise than on Earth's surface. If not, why? Is it a fuel thing? A neutron thing? Is this a stupid question?
pretty good discussion but there are some inaccuracies. fission reactors do not produce energy by converting U to Pb by radioactive decay. fission is not the same as radioactive decay, the physics of each are very different. Fe56 is not the most common element in the universe, not even close, H is the most common element in the universe by far, followed by He; this is corrected later in the presentation.
Everything was amazing until you messed up the microphone just about blew out my speakers and made me crash other than that awesome stuff keep on keeping on
Hydrogen is the most common thing (element) in the universe. Iron 56 is only the most common isotope of iron in the universe. Supernovas outSHINE an entire galaxy, not outlast. Otherwise great video.
This one has bad audio, please watch the revised and updated version of this video here: ua-cam.com/play/PLyu4Fovbph6d9PJ25kXjmEDSAXQp76Mpl.html
WHOOPS LIST!
1) Be sure to plug your ears at @24:49 for the bad audio super-nova
2) I made a bungle in speaking. Neither nickel-58 nor nickel-62 are radioactive. Nickel-58 actually makes up 68% of nickel.
I couldn´t have enjoyed more a video like this.
Just discovered your entire series -- thank you for compiling such an excellent resource to take one from curious to somewhat informed :P
thanks!
Keep going, it's all good. Observe first then research what you see. If you get confused at times you're progressing, closer to the truth and a defining moment.
Wow .. When I really want to know how dumb I am .. I watch videos like this . It is amazing what smart men and women have discovered throughout the years .. My father was one of these super intelligent types that tried to get me interested and curious throughout the years .. Even in his last week of life .. He loved to study and talk about quantum physics .. He passed at 87 with an alive mind
It takes a special kind of mind to pour ones life into research and discoveries of this calibur. Hell, my dad made the first Bradley and MLRS fighting vehicles for the armed forces, and here I sit a humble diesel mechanic. We can't all fill the massive shoes left for us by our fathers. Don't beat yourself up too much. You're probably smarter than most folks you know!
The scary side to that is that there is a vast part of the population that is so undereducated that they deny most of this stuff.
You are much smarter than you think you are. You can do it, just need to start with the basics.
i love this lecture so much, i have listened to it more than 10 times and i understand it better and better every time
Me too
Amazing stuff. Great explanation of what goes on.
I've just found your channel absaloutly tremendous totally under rated
Another excellent lecture.
Absolutely spellbinding. Thank you!
thanks!
Wow, the NRC graph on how Iron is the boundary between fusion and fission is a no brainer to me now that I see the graph. Very cool. Iron has the tightest bonds. I've know for years that Stars could not fuse elements larger than Fe but now I know in the gut why.
Another great lecture which deserves its place at University !
Thanks for sharing this piece of pedagogical art.
Cheers,
Many thanks!
This is an understandable and comprehensive lecture on what it takes for a star to supernova. I'm looking forward to the rest of the series.
you can see the entire stack of videos here: www.jasonkendall.com/WPU/AstronomyLectures/fullcourse.shtml.
This will take you in the correct order.
Great Vid ( but be sure to plug your ears at @24:49 - bit of an audio super-nova )
whoops. sorry about that....
Can you explain "iron 56 is the most common element in the universe" ? (@ About 11:30) I thought hydrogen, then helium were most common.
Yeah, I’m talking fast with one take. You are correct. H then He. Then... O, C, Ne, N, Si, Fe, Mg, S. Iron is #8
I took the statement to mean the most abundant heavy element produced by nucleosynthesis...much\most of the H & He predate stars...I guess I don't think of O, C, N & even Si as "heavy" elements...I suppose it matters what you are comparing them to
@@Bertemus60 Makes sense. He touches on it again around 40:15.
I absolutely loved your content.....had i been born in the US or any European countries, I definitely would have been an astronomer.....I live vicariously through you and absolutely loved every minute of it....
Thanks
22:40 “You’d be dead!” 😂😂 dont know why I found the way you said that really funny
I’m pretty sure I imitated a movie line.... can you figure out which one?
30:00: The bright comet at the bottom of the picture is C/2006 P1 (McNaught), also known as the Great Comet of 2007. Links: apod.nasa.gov/apod/ap070330.html and en.wikipedia.org/wiki/C/2006_P1
Thanks again!
What is the mass of our own star and what is the name of it's state?
I don't know why, but your approach to teaching this clicks for me so much better than many other channels, even ones with far flashier presentation or sexier narrators. (Come on, everyone loves the buttery smooth voice of some random British bloke with no real physics training or education degree.)
It's just arranged in a way and presented with aids that works for my brain. Wish I had access to this 20 years ago... Might have chosen a very different life path if I knew I could actually retain this stuff.
I love your video's and I love to watch the night sky on a dark spot, the reason that I love your vidoes is that you involve enough physics to keep me interested, without getting too complicated for my background knowledge from school.
Great lecture! However, I would like to comment on two nickel isotopes mentioned at 11:01: Both nickel-58 and nickel-62 are actually stable. More precisely, nickel-58 is observationally stable ("believed to decay by β+β+ to iron-58 with a half-life over 7×10^20 years"). From: en.wikipedia.org/wiki/Isotopes_of_nickel
Another link ("Isotopes of the Element Nickel"): education.jlab.org/itselemental/iso028.html
thanks for the correction!
Thanks for sharing ... just found your lecture after reading Oppenheimer & Snyder, your lecture helped appreciate the context ...
(That was: On Continued Gravitational Contraction, J. R. Oppenheimer and H. Snyder - Phys. Rev. 56, 455 - Published 1 September 1939)
Glad to hear it. This is what I hoped to hear.
When I was young I hated doing presentation in front of my classroom and I was collapsing even in harder than a supernova!
This is an excellent lecture - many thanks!
Thanks for another entertaining and instructive video!
Excellent, keep bringing these insights!
11:00 58Ni and 62Ni are listed as stable. Did you mean Fe? en.wikipedia.org/wiki/Isotopes_of_nickel
Yes. I really should redo this one to get rid of slips of the tongue.
About the info at 36:27, for some extra context. Solar neutrino flux at earth distance is about 20 billion per second per square cm. The SN1987A, produced double or triple of that (for about 10 seconds), while being 11 billion times further away from earth than the sun. And you need to also know that surface area scales with square of distance, not linear. So it was maybe thousand billions of billions of times higher at 1AU distance from the core.
Core collapse supernovae are fascinating.
Wonderful lecture. Thank you!
You just got another subscriber. AWESOME video!
(Except for "iron 56 is the most common element in the universe", that triggered me lol (read further down you corrected it)).
You just clarified so many things that other sources refuse to go in depth on, like WHY exactly Iron is so detrimental to a star's support. This is the first time fusion vs fission was explained this way and its just so awesome to understand it like this now.
Thank you!
Yeah. I cringe when I hear myself make that mistake. All with the one takes....
one minor thing, fission reactors don't decay Uranium down to Lead, fission typically results in two smaller nuclei in the 80-150 range.
Thanks for this! I'll incorporate it into a later edition...
Cool videos. Really informative. 99% of the supernova energy is packed into neutrinos? Well, it's a quite effective way to get rid of all the energy of the star's core. It is fascinating that these dramatic processes in nature are almost undetectable and unvisible. All the light drom the supernova is just a small shadow compared to the almost unvisible neutrino outburst.
Excelente vídeo. Perfectamente explicado y detallado. Gracias por esta clase magistral.
Saludos! 😉
At 11:32 I think you misspoke. You said Iron 56 is the most common element in the universe. Not even close, unless you mean maybe by weight? Or you misspoke, or I heard you wrong. Which is possible, I've got one ear less sensitive than the other, so I sometimes hear things wrong.
Yes I misspoke. I need to do an addendum video.
Why the drop from Helium-4 to Lithium-6 and -7?
The weird one out is actually He4. This nucleus is unusually stable and so pokes out above the curve.
The "why" is hidden somewhere deep in the ugly-math of Quantum Chromodynamics, but there has been an empirical observation for a while that some nuclei have "magic numbers" of neutrons and protons that give them unusual stability.
He4 is "doubly magic", as both it's neutron count and proton count rolled the magic snake-eyes.
Excellent presentation. I have a question: given the intensity of the big bang, why only hydrogen and helium? Why not more other stuff, like a supernova?
Watch my Module 14 group on the Big Bang and Cosmology. You'll see why.
ua-cam.com/video/n2iXxIINxG8/v-deo.html
An impressive, detailed description of nuclear processes. Depending on how much use is to be made of it, apart from casual browsing, I think it would benefit from a little boiling down and tidying up. It sounds like a spontaneous illustrated talk and although it does a great job of enthusiastically imparting a lot of interesting information there is a fair bit of rapid fire repetition that had me clicking on the advance 10 s button. The wealth of content might be communicated a little more effectively with fewer words. All the same I found myself learning new things and understanding previously learned aspects of supernova more clearly than before, and have heard few utube presentations like it.
thank you so much Sir.....this video was one of the best lectures I have ever seen.
So nice of you
Excellent helpful video
Glad you think so!
what an interesting presentation. Very informative but easy to follow for non-experts like me.
Thanks. I'll likely need to do some more on this one, because a few people have contacted me about the nature of nuclear fusion physics.
@@JasonKendallAstronomer I only discovered your lectures very recently and have been following some of them. Found them immensely informative with enough detail to keep non experts like me interested but not bogged down by heavy maths. Amongs the best introductory astronomy I have so far come across on the web.
I do appreciate that!
The thorough explanation of a cosmic catastrophe.
24.55 RIP headphone users
Boost
24:49
It was even worse than I expected, knowing full well what was coming 😣
I love these
What if you had 10000 SPF, could you survive
How do the odd numbered elements get created ?
There are many ways. Most common fusion and fission actions are... proton capture, alpha particle capture, beta decay and capture. There are many others, but these are the basics. Neutron capture, too. As they build in various paths, some are energetically favored than others, so the most common reactions and the “easiest” win the day.
10^48 Joules for the neutrino burst energy output - may be an order of magnitude (or a few) too high? if correct, that would be something like 6 times total mass-energy of the Sun. In terms of luminosity, it's not just outshining the galaxy, but compares to the entire observable Universe.
Think I have watched this 4 times
Thank you, it is clear.
Do you have any material of things such as pair instability supernovae, or is there anything like that in the works?
Amazing video, it's difficult to find a video as comprehensive as this so thank you for uploading this.
I’m currently working on exactly one of those videos. Thanks for asking. Please subscribe and watch for it coming.
Thanks for these vids. Great information
Thanks for a wonderful video. I realize that the confirmation for this is more recent than the video, but the heaviest of elements are made from the merger of neutron stars, not super novae.
Yes, I just talk faster than a bear of little brain should, I should think
I’m guessing the iron core star has a rotation with a significant angular velocity. So can we expect that it would have an extremely strong magnetic field?
Update: some of elements heavier than iron is now believed to come from neutron star mergers like GW870817
Thanks for this. I'll do a revision soon!
I was under the impression that past a certain pressure & temperature, iron/nickel would fuse into zinc, but at the cost of absorbing energy, thus accelerating the core collapse? Is this correct, or only for a certain mass range?
Zinc is definitely on the "bad side" of the Iron Mountain. Anything with an atomic mass greater than Fe/Ni will consume energy to be produced, and thus hasten the collapse.
Hi professor, a question about the core bounce: when the core contracts that fast is its angular momentum preserved, meaning a really fast spinning core before it bounces back?
That's very correct! That's why neutron stars spin so fast. I'm sure you've watched this: ua-cam.com/video/PIgllxJIbW8/v-deo.html. But I leave it here just in case...
Great series, but why is the first 15 sec always so loud!
Well done!
Didn't they find a neutron star remanent at the epicenter of the explosion recently?
Which one?
@@JasonKendallAstronomer I know the progenitor of SN 1987 A was Sanduleak -69 202. I think it was a recent discovery after the glow dimmed down.
Thanks for the note!
Outstanding description of a supernova explosion.Just one question: any assumptions in the whole sequence that leads to the final state ( BH or neutron star, I believe ). No chance that the conservation of initial angular momentum could stop the continuous shrinking due to sort of balance between centrifugal force and gravity before reaching those two possible final states?
Thanks! Likely not. Remember that black holes are described by only three things: mass, rotational spin and electric charge. The last one is not known to matter at all in reality. The first is very important. But the second is also important and has been tested in the weak regime, with the Gravity Probe B experiment, modeling gravitational waves, and modeling the image seen by the Event Horizon Telescope. It doesn’t stop the collapse.
Given photon wandering taking a long time for fusion-created light to make it out of the core, once the heavier stages of burning start, is there any outward signs the burning mode has changed?
11:30 "Iron 56 is the most common element in the universe". I don't think that's correct. Most people would say hydrogen. Could you explain?
Yeah, that was a verbal blooper of mine
Why does eta carinae have blasts only on the poles and equator? A mag field strong enough to hold back an exploding star?
www.pitt.edu/~cejones/GeoImages/0PlanetaryFormation/StarDeath/EtaCarinae.jpg
I absolutely 💙 Cosmology.
Can you please do a presentation on one of the most occulted subjects .. "micro novae"
Sounds interesting!
@@JasonKendallAstronomer Thanks ...becomes more interesting "in light" of the fact it's been officially entered into the wiki as being discovered only in 2021 but there is much information of scholars and professionals sending in research regarding the subject going back years. Of course they were met with great resistance and imho solar cycles should scale like everything else.
I have become extremely fascinated with the spotlight of influence vs the occultations of science knowledge and this subject of solar micro bursts or the solar micro novae has been a fun one. You also have mainstream influencers out their saying we don't have much info/data on the sun. Your content has been quite an eclipse to the contrary! Thank you!
What about direct urca process?
When they say that a neutrino will need a light year length of lead for it to have an even chance of getting absorbed.. does that apply to these high energy neutrinos?
What about heavy elements produced in binary neutron star mergers?
I cover that lightly in my Gravitational Wave and Gamma Ray Burst sections. They are, of course, significant contributors, so I'll eventually have to make an addendum video. I'm mostly covering the fiducial introductory concepts of fusion.
en.wikipedia.org/wiki/Supernova_nucleosynthesis#/media/File:Nucleosynthesis_periodic_table.svg
this shows typical expected sources as we currently know them.
I was team physician for the Pittsburgh Pirates when you tore your ankle up.
Thanks for your care. The transition to academia was hard
@@JasonKendallAstronomer FYI I am an amateur astronomer and enjoy your posts. Question: any thought on the origin of supermassive black holes at the centers of most spiral galaxies?
Neither nickel-58 nor nickel-62 are radioactive. Nickel-58 actually makes up 68% of nickel.
Hi, Jason. I wanted to sign on to your website to watch your videos in order. However, your site is listed by Microsoft 10 as being "Not Secure", so I will just continue to enjoy your UA-cam Channel. I have read that this situation maybe propagated by large software security companies to push their products. It is hard very challenging to justify taking the risk when there has been so much foreign interference now though perfectly innocent sites. I am sorry, yet appreciate your generosity in using the YT platform for sharing your experience and this fascinating information with us!
Sherill, your trepidation is justified. I guess the era of owning and maintaining your own website is over. I'll have to look at alternatives for distributing my static content. In the meantime, to show I'm not a "bad actor", you can always look me up on my William Paterson University website. In fact, I may move the summary content there. Furthermore, I did notice a steep, rapid decline in viewers recently. Perhaps people wanted to learn, but found what you found. I'll look into it. Likely, though, I'll be forced to use a more standard web hosting provider, that costs more, and gives me less....
As best I can determine, the only elements heavier than iron that are involved in life are: cobalt, copper, zinc, selenium, molybdenum, and iodine. Most of these are in tiny quantities, raising the question of whether life truly requires them, or if they're more of a matter of convenience, with functions that could be provided by something else. Cobalt, the linchpin of vitamin B12, is one of those with very tiny quantities, but it seems to be ubiquitous throughout the biosphere. But I think it's natural to wonder if life could occur with no supernova to seed the environment with heavy elements.
what I would like to see is a graph showing the star's mass as it drops from the hydrogen envelope down to the iron core. As a percentage graph. I would think the lowest hydrogen compaction level would be a large part of the total mass of the star.
Just woke up to this, and was wondering when Adam Savage started doing physics lectures...
Probably a 'silly' question here, but i think it would be even MORE silly not to ask...
I've learned that fusion produces energy only up to the iron/nickel level (I think of this as being akin to exothermic as net energy is RELEASED).
Beyond the iron/nickel boundary, it no longer releases energy (which I think of as being akin to endothermic).
We're constantly told that it all just STOPS at the iron/nickel level, but surely there is SOME degree of heavier elements produced? (Even though their production is a net DRAIN on total energy, I cannot help but think that they are 'occasionally' still produced, even if the actual probability is fairly low...
Assuming they ARE produced at all, what would be the realistic percentages involved for Cu and other heavier elements? Below 1%??? Below 0.0000000000001%????
Perhaps any such 'heavier' elements produced have a higher probability of becoming 'fission' fuel at the immense temperatures involved and they are therefore annihilated almost immediately????
It'd be interesting for me to know...
This is a really good question. The environment in the core of a collapsing star becomes so dense and saturated with high-energy photons and neutrinos, that all the heavy elements that do exist are, in fact, annihilated. However, the momentary explosion also does produce some heavy elements through rapid-neutron-capture processes. These then decay down to more stable isotopes of the same or other elements. That's what the major part of the glow from a supernova remnant actually is, the fission decay or nucleonic decay (radioactive decay) of elements. So, yes they are created, but not directly in the core, but in the shockwaves outside the core. The core is likely pure neutrons, or pure quarks, depending on mass and composition prior to the supernova event.
@@JasonKendallAstronomer
Thanks HEAPS for the response...
I have one further question (if you have the time...)
Imagine we're a day / week / month BEFORE core collapse begins in our hypothetical high-mass star.
i.e. There's still enough outward pressure to remain in equilibrium with the inward pressure of gravity since the final stage(s) of fusion are still ongoing.
Is there ANY probability at these SIGNIFICANTLY lower temperatures / pressures to create ANY of the 'heavier than iron / nickel' elements?0
(While the 'average' temp / pressure throughout the core might be insufficient, I cannot help but think that there could be 'hot spots' within which the local conditions ARE sufficient to support such production? I accept that it's quite feasible that any such elements may well be annihilated at a faster rate than they're produced leading to an overall population that tends towards zero)
Imagine matter being so dense that it stops _neutrinos._ Insane.
Yeah, and the stopping distance is quite short, on the order of tens to hundreds of miles (size scale of the iron core)
As a bit of intuitive analogy, 20 to 40 ms of delay as an audio effect is a really quick snapback, like two drummers, juuuuust slightly out of time.
This is an older video, and I'm working on a complete re-recording. Thanks for the note!
@@JasonKendallAstronomer I don't mind the old videos, and will happily listen to new ones. Thanks very much for the public outreach education. This kind of thing is true to the spirit of the original hopes for the internet.
I think a temperature of 10bnK will correspond to around 1Mev rather than 10Mev. 10Mev would require around 100bnK perhaps... Does high density also play some role?
One this I do not understand. If the envelope is few AU, how it can all infall and rebounce in milliseconds? It takes dozens of minutes at the speed of light.
It’s the core that does so, not the entire envelope. For FULL collapse, you need hypermassive stars.
Nature's fireworks and life giving event
All this is probably going on inside Betelgeuse now.
I cringe with some of those mistakes "Iron is the most common thing in the universe" Last I checked Hydrogen Helium Oxygen is way more Iron is in the top ten elements in our Universe but it isn't anywhere close to the most common. Also worth noting that Red giants can make small amounts of certain heavier elements via decay limited neutron capture chains and the really massive elements are now understood to come from far more exotic processes involving Neutron Stars. Either via Neutron Star collisions or the extremely rare destruction of a newly formed Neutron stars via "aborted" Supernovae called Collapsars. Normal Supernovae aren't extreme enough to get you Uranium since slow Neutron capture gets terminated at Bismuth.
It is interesting to note there have apparently been several supernovae in our galaxy since Kepler saw SN1604 saw and SN1987A they were just invisible to use due to the intervening gas and dust (The "curse" of being inside our galaxy). Of course both were Type Ia supernovae resulting from white dwarf mergers and thus not core collapse so no Neutrinos would have been visible.
The name separation between Type I and Type II supernovae based on hydrogen has the unfortunate consequence of separating the more massive classes of core collapse supernovae Type Ib and Type Ic from their less massive cousins since the reason they lack Hydrogen, or in the case of Type Ic Helium as well, is that their progenitor stars stellar winds were so strong they stripped away their Hydrogen and or Helium envelopes. These stars known as Wolf Raynet stars are a fascinating class of stars which depending on their mass and metallicity result in black holes or WNh are probably the most mind boggling of these as they are fully convective due to intense catalyzed nuclear reactions in their cores it is hard to fathom 100+ solar mass behemoths burning through nearly all of their hydrogen R136a1 being a crazy example with over 315 solar masses and having burned through 60% of its hydrogen. Of course it isn't even known if stars of that type even die in supernovae (as oppose to collapsing strait into a black hole) so I'm getting a bit off track.
That said one of the more interesting discoveries from the combination of the geological records of the Earth and the Moon is that over the the interval of 20-2 million years The Earth had some close encounters with a number of nearby Supernovae the last of which exploded about 2 and a half million years ago a little over 400 light years away. Evidence comes in the form of short lived isotopes such as Iron 60 buried within sediments deposited around this time as well as our solar systems position within a large "local bubble" formed by the expanding shock waves of these supernovae and filled with under dense gas and dust radiating in X-Ray light. Currently our solar system is near the edge of this region and will "soon" leave the supernovae remnant but it seems we missed quite a light show. Of course there is some, still somewhat controversial but growing, evidence that suggests these supernovae probably played a role in altering climatic conditions on Earth. The most well supported of these effects currently is probably the deposition of energy into the Earth's atmosphere which at the distance suggested by tracking back trajectories it can be determined would be concentrated in the upper troposphere driving increased lightning frequency by lowering the critical threshold for storms to generate lightning strikes. This meshes well with evidence from the fossil record suggesting that over the last 20 million years fire frequency increased driving more fire based ecology in particular the rapid diversification of grasses and the establishment of the Earth's first grasslands. Yes Grass and thus grassland environments haven't existed until about 20 Ma with modern grasses only evolving about 30 million years ago and only becoming a significant component to Earth's flora in the last 20 million years prior to that you just had various types of forest environments. This change which seems to have been very important in our own evolution fits neatly with our close approach to a massive star forming region as our solar system passed through the local arm segment of our galaxy.
Yeah, I do need to do an edit of that video. I do these long one-offs. Now that they are getting a lot of attention, I need to revisit a couple of them.
@@JasonKendallAstronomer not to be a negative Nancy, but I noticed you called Sn "Scandium" when it is Tin. Just food for thought =]
you said brighter than 5 billion suns -- the text said one sun for 5 billion years. A little confusing --- perhaps a chart or Mev or Gev or something larger?
It never occurred to me to ask before...
But does nuclear FISSION ever happen in a star?
Just thinking that you've got these heavier elements later in stellar life under crazy pressure/heat, all kinds of particles flying around... Seems like it could happen?
And I mean in a broad sense it's just like a symmetric process to fusion. I understand the basics of fission and realize you want less stable fuel, but it's also more favorable conditions energy -wise than on Earth's surface.
If not, why? Is it a fuel thing? A neutron thing? Is this a stupid question?
pretty good discussion but there are some inaccuracies. fission reactors do not produce energy by converting U to Pb by radioactive decay. fission is not the same as radioactive decay, the physics of each are very different. Fe56 is not the most common element in the universe, not even close, H is the most common element in the universe by far, followed by He; this is corrected later in the presentation.
Thanks for the corrections. I'm doing a full re-recording of this video in the coming week.
This propably is here, but 10 000 000 kg is exactly 10 thousand tonnes, not hunreds thousands tonnes ( one ton is 1000 kg)
Thanks for the note! I'll fix in an update...
2022 comment. It now appears the heavier elements are formed when 2 neutron stars collide.
Watch my videos about gravitational waves.
And thanks, I'll update shortly...
Everything was amazing until you messed up the microphone just about blew out my speakers and made me crash other than that awesome stuff keep on keeping on
sorry about that. I may get around to re-uploading it, but I put a tag in the video to turn down volume...
@@JasonKendallAstronomer its perfect the way it is I learned so much I'm watching all of them thanks for the time you spent to make them
Hydrogen is the most common thing (element) in the universe. Iron 56 is only the most common isotope of iron in the universe. Supernovas outSHINE an entire galaxy, not outlast. Otherwise great video.
Thanks for the note. I’ll update it when I do the remaster.
@@JasonKendallAstronomer I found your channel yesterday, and will spend many hours going through your videos. I love learning about the stars.