Starts With A Bang podcast

• Starts With A Bang #115 - Dwarf galaxies in isolation

  Sure, it's easy to look out at the Universe and take stock of what we find. Although spiral and elliptical galaxies house the majority of the Universe's stars, represented locally by galaxies like Andromeda and our own Milky Way, the overwhelming majority of galaxies are much smaller and lower in mass than we and our cousins are. These low-mass galaxies, the dwarf galaxies in the Universe, represent upwards of 97% of all the galaxies that exist.However, while most of the dwarf galaxies we know of are found as satellites around larger, more massive galaxies, they aren't good laboratories for helping us understand the Universe as it was long ago. Back during the first few billion years of cosmic history, it wasn't just dwarf galaxies that formed the majority of starlight in the cosmos, but isolated dwarf galaxies: dwarf galaxies that hadn't yet interacted with larger neighbors.We can best understand those early-stage galaxies by studying their late-time analogues: isolated dwarf galaxies in the Universe today. On this edition of the Starts With A Bang podcast, I sit down with Dr. Catherine (Cat) Fielder, and we talk about some of the nearest, most isolated galaxies of all: including some that have been imaged with flagship-quality telescopes. What have we learned about them so far, and what else are we hoping to discover? Find out here, today!(This three panel image shows a ground-based, wide field view of the entirety of galaxy NGC 300: one of the closest spiral galaxies outside of our Local Group. Though this galaxy is relatively isolated, there are dwarf galaxies nearby it that are even more isolated than this galaxy itself, making them excellent objects to teach us how tiny galaxies grow up in isolation from large, major galaxies. Credit: ESA/Hubble and NASA)

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• Starts With A Bang #114 - Pluto and Charon

  Out there in the Universe, there are tremendous, uncountable numbers of planetary systems just waiting to be discovered. But stellar systems won't just consist of planets orbiting a parent star; there will be moons, asteroids, Kuiper belt-like objects, and many of them will be bound together into their own rich sets of systems, with both irregular and round bodies comprising these planetary systems.Here in our own Solar System, we have at least three notable large, terrestrial-sized bodies with impressive lunar systems of their own: the Earth-Moon system, the Mars-Phobos-Deimos system, and the Plutonian planetary system. Pluto, interestingly, is orbited by Charon, which is very large and massive compared to Pluto, an unusual and possibly unique, or most extreme, configuration of all known such bodies. But how did it get to be that way? That's the topic of this podcast, and the research focus of this month's guest: Dr. Adeene Denton.It's kind of amazing what variety can emerge in terms of surviving systems from ancient planetary collisions, but by running simulations and understanding the geology of these worlds, we can learn more about what's possible, likely, and unlikely in our Universe. Dive into this fascinating conversation and learn some cutting-edge science along the way!(This composite image of Pluto and its largest moon, Charon, was based on photographs taken by the New Horizons mission as it flew by the Plutonian planetary system back in 2015. Charon's appearance is vastly different from Pluto's, but both bodies are shown with the correct relative size and albedo. Credit: NASA, APL, SwRI)

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• Starts With A Bang podcast #113 - Weird stars

  When it comes to stars, most of them, for most of their lives, behave in a very similar fashion to the Sun. In their cores, they undergo nuclear fusion, which provides energy and creates radiation, and that outward radiation pressure holds the star up, internally, against gravitational collapse. For most stars, this balance between the pressure from outward radiation and the inward force from gravitation is nearly perfect all throughout the star, leading to an equilibrium state. But some stars aren't in this kind of equilibrium at all. Instead, some internal process actually drives the star in a fashion that causes it to pulsate: overshooting equilibrium in both directions, as it alternatingly expands and cools, and then contracts and heat up in a cyclical fashion. These species of intrinsic variable stars, including Cepheids and RR Lyrae stars, are not only of profound importance when it comes to understanding stellar evolution, but for unlocking the secrets of the distant Universe. How do we understand these stars today, where are the frontiers, and what do we hope to learn about them in the coming years and decades? Especially as we transition into the era of "big data" in astronomy, where we aren't observing individual stars in detail but rather thousands upon thousands of similar stars all at once, the answers to these questions are rapidly changing. I'm so pleased to share the first episode of 2025 with you, featuring our guest, Ph.D. candidate Catherine Slaughter, who takes us through all this and more. It's a fascinating look into stellar physics, with possible implications for our own Sun's fate, that you won't want to miss! (The featured image shows the star RR Lyrae, as imaged by the digitized sky survey back at the turn of the century, using data from the Palomar and UK Schmidt telescopes. Credit: Digitized Sky Survey - STScI/NASA)

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• Starts With A Bang #112 - Galactic Archaeology

  When we look out at our home galaxy, the Milky Way, we have to recognize that even though it's been growing and evolving for 13.8 billion years, we're only observing it as it is right now: a snapshot in time determined by the light that's arriving in our instruments right now. However, just like we're living "right now" in human history but can, through the science of archaeology, learn about historical events that happened many thousands of years ago (before recorded history) or even earlier, we can learn about the Milky Way's history through the astronomical equivalent: galactic archaeology. How do galactic archaeologists do it? They look at as much data as possible, across many wavelengths of light, including at many rare and obscure species of stars, in as many locations as possible and to the greatest precisions possible all at once. By combining these different lines of evidence, we can arrive at a coherent and compelling picture for how our little corner of the Universe grew up, including by reconstructing the merger history of the Milky Way. Surprisingly, it isn't only the "big data" missions that are contributing to this understanding, but even smaller, less heralded (and more accessible) telescopes, with the right equipment and sets of observations, can make a huge impact. Join us for this episode, where astrophysicist and observatory director Elaina Hyde joins us, helping us better appreciate the wonders of our own cosmic past! (This illustration of our Milky Way shows an ancient galactic stream wrapped around our galaxy's plane at nearly a 90 degree angle: evidence for a recent and even ongoing merger in our galaxy's history. Credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech))

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• Starts With A Bang #111 - Black Hole Jets

  In this Universe, there are a few objects that are just larger, and a few events that are just more powerful, than others. As far as size goes, the cosmic web creates some of the largest features ever discovered, with the largest galaxy filaments and the largest regions devoid of galaxies spanning as much as ~2 billion light-years. No robust, verified structure has ever been found that's larger. Meanwhile, as far as energy and power go, collisions of galaxy clusters are the most energetic events, outstripped only by the Big Bang itself. However, nearly rivaling galaxy cluster collisions are the strongest black hole jets ever seen, capable of emitting trillions of times the energy of a Sun-like star, but also capable of sustaining those energies over timescales of a billion years or more. Astronomers have just set a new record for the longest black hole jet with the discovery of Porphyrion, which spans a whopping 24 million light-years across! How did this jet and others like it come to be, and what effects do they have on the larger Universe, and how do they get generated from such physically small objects (i.e., black holes) to begin with? That's the subject of the latest edition of the Starts With A Bang podcast, featuring Dr. Martijn Oei: the discoverer of Porphyrion himself! We get deep into the physics and astrophysics of black holes and their jets, which have profound implications for how structures get carved and magnetized onto the scales of the cosmic web itself. Buckle up and tune in; it's a wild ride ahead!   (This illustration shows how black hole jets can be as large as the scale of the cosmic web itself, with Porphyrion, as illustrated here, setting a new cosmic record with its bipolar jets spanning 23-24 million light-years across. Credit: Erik Wernquist/Dylan Nelson (IllustrisTNG collaboration)/Martijn Oei; Design: Samuel Hermans)

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