Supernovae: The Brilliant Endings of Massive Stars - Michael Pajkos - 01/12/2024

When stars heavier than our Sun reach the ends of their lives, they undergo massive explosions known as supernovae. But why do they explode and why do some of them result in neutron stars or black holes? Join us for a 30-minute lecture investigating supernovae, followed by a panel Q&A consisting of several astrophysicists to answer your questions about astrophysics and space science. Timestamps below:
00:00 Announcements
04:51 Intro to Supernovae Presentation
06:00 Supernovae Presentation
41:20 Q&A for Supernovae Presentation
41:51 "Why do some stars have a sharp transition in their interiors?"
43:59 "How do we interpret the gravitational wave signal from the supernova?"
46:25 "Why do constellations never change?"
48:55 Intermission
52:20 Q&A Panel Introductions
55:32 "Are black hole remnants from supernova similar in size to neutron star remnants?"
57:29 "Could we ever feel gravitational waves?"
1:01:04 "How long does a supernova last?"
1:06:46 "How do we identify the location of a gravitational wave source?"
1:09:39 "What's hotter: a star's core or a neutron star's core?"
1:12:47 "How much does chaos play a role in a supernova's collapse?"
1:18:05 "Can the r-process create new elements instead of just new isotopes?"
1:19:53 "What percent of your research is observation-based vs theory-based?
1:21:43 "Are we seeing more supernova now than we did 100 years ago?"
1:26:00 "Explain dark matter, dark energy, quarks, gluons, and supernova locations?"
1:36:40 "What forces contribute to stellar collapse?"
1:39:23 "How fast do gravitational waves travel; how long are they present?"
1:42:52 "Are certain types of neutrinos more observable than others?"
1:45:26 "Do the gradation waves in supernovae travel faster than light?"
1:46:17 "Can we detect supernovae before they explode?"
1:49:29 "Why were the neutrinos detected from SN1987A exciting?"
1:50:38 "What does it mean for the universe to be flat?"
1:53:20 "How does a supernova become a black hole?"
1:54:25 "Has JWST revealed more mature galaxies at the edge of the universe than expected?"
1:58:56 "Does our Sun have a density gradient similar to the supernovae discussed?"
1:59:45 Concluding Remarks
Title: Supernovae: The Brilliant Endings of Massive Stars
Speaker: Michael Pajkos
Abstract:
When stars heavier than our Sun reach the ends of their lives, rapid changes inside the star can result in it exploding as a supernova. While these supernovae may produce brilliant outbursts that are visible across the universe, many will often fail, producing instead a stellar implosion. In this talk, we will review the science that governs whether a star will turn into a cosmic firework or stellar dud. We will explore the hearts of these cosmic furnaces that produce unique objects like neutron stars and black holes. Lastly, we will discover what items on a grocery list, stellar explosions, and humanity all have in common.
Photo Credit: M. Weiss / Harvard CfA

[@zapfanzapfan]

Very good presentation and good sound quality. Beetlejuice, beetlejuice, beetlejuice... 🙂

[@CaltechAstro]

Thanks, Zap! Yeah, I think Michael did a great job on a challenging topic. Glad we got the sound working better than last month!

[@Odin412z]

Great lecture with excellent sound quality!

[@CaltechAstro]

Thank you!

[@proceduraldad2578]

The supernova question I've always had is-- I understand that like all the gold on earth is from supernovas. But there is so much gold. I get that stars are really big. So if a star makes some gold, it's made lots of gold. But like... how does it get here? How did it fly through space? Was it a huge cloud of gold? Were they individual gold atoms or were they bonded together? How did it end up... stuck together, during planet formation? Because if I find gold in a mine its many many many gold atoms bonded together. I can visualize hydrogen and helium collapsing into a star over millions of years. For the metals I can't quite get it.

[@CaltechAstro]

Very interesting question. It's generally thought that gold (or any type of atom) is expelled from stars and supernovae alongside many other types of atoms to mix with the ambient gas and material from other stars. This material is known as the interstellar medium (ISM) and will later go on to form new generations of stars. For the most part, the gold (or any other type of atom) is unlikely to be clumpy, as it should be reasonably well mixed in that gas. New stars and planets form out of this ISM material. Geological processes after the Earth's formation will concentrate certain atoms in certain areas throughout the Earth, which can lead to gold being found near quartz veins and so on. I'm not an expert on the geological processes that lead to certain atoms and minerals being in certain configurations on the Earth, but I believe that is what leads these atoms to be in the locations we find them here. In space, the atoms are probably well mixed.

[@proceduraldad2578]

​@@CaltechAstro This is fascinating great information and gives me a number of key words that I can use to do additional learning. Thank you!

[@CaltechAstro]

@@proceduraldad2578 Happy to help!

[@julia-miguelbernardes3038]

Dear Prof. Michael Pajkos, I am writing to inquire about something difficult for me to verbalise. I am wondering if you could elaborate on the analogy with musical instruments' or voices' sound waves as propagated on Earth on land (more or less humid, more or less hot/cold as far as "room"/outdoors temperatures go, differences on altitude, etc.). Not underwater (where sonic sound *does* propagate), not inside an echoic chamber where sound does *not* propagate (i.e.,where all that the human ear can perceive/detect is its own heart beat and other inner physiological movements). I am under the impression that sound waves need a certain medium/certain media in order to propagate. Some materials do work as filters and that's one of the ways we "tune" concert halls - with [our] spacial dispositions and materials' dispositions in [our] space. Can you elaborate on the medium through which gravitational waves propagate? Does it have to do with some "fluid" combinations of the elements you mentioned (potassium, silver, zirconia, aluminium, calcium)? If yes, how do the elements interact such that they would constitute a coherent enough medium for wave propagation? How does the analogy with sound waves work? I am also stuck in the core (nucleus of too many "things"?) or point of origin of the wave - if You could also elaborate on the point of origin of the wave I would appreciate. Sorry to be not very literate, but Cameron said once that the remedy to not knowing is to try to learn and not to be afraid of asking stupid questions. I do not mind my questions being stupid, hilarious, etc. n.b. My name is "granny" Julia-Miguel R. Bernardes but someone got hold of my normal YT account and I do not have its password anymore as of Jan 31st, 2024. Love you, CaltechAstro kids.

[@ms.julia-miguelr.bernardes9717]

Hi Cameron, as of Jan 27, 2024 I have no idea what my password is for this yt account and I failed to tattoo it to my body (no toes' space left for more passwords 😉). I am trying to update my Caltec Astro playlist of the public lectures and come back slowly. Is there an obvious way to automatically keep my play list upgraded? Granny loves you kids. Stay beautiful, for only human-made beauty will ensure the species' thriving.❤

[@CaltechAstro]

Hi Julia! Our Caltech Astro Public Lecture playlist is here: kzbin.info/aero/PL0yNjaybQwdudycotA6z0DFK5DZaXWE1J . You can also see all of them linked on our website here: www.astro.caltech.edu/outreach/past-events/past-stargazing-lectures We hope to see you again at one of our live-streams!

[@frankmurphy8850]

Is this for 5 year old?