Dr. Tim Cunningham -- White Dwarfs Sometimes Eat Planets

A white dwarf star is the compact, dense remnant of a once-thriving solar system. Long after the original star has died and turned into a white dwarf, it can still interact with its solar system. We can even see white dwarfs eating up the rocky debris that once made up their solar system, and apparently making sense of all of this requires a detailed understanding of how convection works in these dead stellar remnants.

How did the planets form? What was going on in the first few brief million years of our solar system? And how did it impact what we see in our solar system today? Dr. Merel van 't Hoff takes us on a journey through astrochemistry to understand the planetary wombs that house solar systems in their prenatal years.

What kinds of things do neutron stars do? They can smash into each other, producing bright flashes of radiation and strong ripples in spacetime that can be detected across the universe! Or, a neutron star can just be sitting there, and its magnetic field might suddenly shift and produce a dramatic burst of radio waves! But mainly, neutron stars are super-dense and super-complicated, giving us a probe of fundamental physics in its most extreme limits. Dr. Wen-Fai Fong tells us all about how we can learn more!

Just how big can black holes get? Well, they can get super-massive! That is, millions to billions of times as massive as the sun. How do we know this? We've detected these supermassive black holes at the centers of galaxies in a number of ways, and Dr. Daniel D'Orazio has been leading the way in figuring out new ways we can detect more, especially if it's not one but two black holes orbiting one another in a binary system.

In this week's episode, Dr. Abigail Polin joins us to answer your questions from the internet, on a variety of topics tangentially related to astrophysics! Questions range from the basic and fundamental to the obscure and weird. Answers are totally unprepared and rambling. Our guests this week are Dr. Abigail Polin, PLUS an extra-special mystery guest!

A black hole is so dense, its gravitational field prevents anything from escaping, including light. You would think that would make them the "blackest" things in the universe; how in the world do we know they are there? Dr. Andrea Derdzinski tells us about how we detect black holes, either due to the gravitational waves they produce, or due to their interaction with material orbiting around them, which paradoxically can make them some of the brightest objects in the universe.

Up in Orion's shoulder sits Betelgeuse, a supergiant star near the end of its life. The surface of Betelgeuse has been roiling and pulsing for centuries, as long as humans have recorded its modulated luminosity. Dr. Jared Goldberg is a postdoctoral research fellow at the Center for Computational Astrophysics in the Flatiron Institute in New York City. Dr. Golberg has been developing computer models for Betelgeuse to help understand and interpret its oscillations over time.

What happens when a black hole eats up a star? Apparently a lot of things happen, and if you wait around awhile and look in the radio, even more things happen! Dr. Yvette Cendes tells us what it's like to be a radio astronomer and about her latest research into tidal disruption events (TDE's), when a black hole shreds up a star and eats it, producing a dramatic light show across the electromagnetic spectrum.

Some things happen out in the universe that are too powerful to make in a lab. Other phenomena are so coherent and well-ordered, we can't figure out how they can be made without a lab! Fast radio bursts are an incomprehensible combination of both; they are extremely powerful, highly coherent, and very rapid bursts of radio emission. Dr. Maxim Lyutikov spends a lot of his time pondering how these bursts could possibly be made, and all the data seems to point to the most extreme physics imaginable: neutron stars at the highest densities we can imagine, with extremely strong gravity and with a magnetic field a quadrillion times stronger than the Earth's magnetic field.

How do we know so much about supernovae, when all we see is this little point of light getting brighter and then dimmer over time? Given this minimal data, we can often say what type of star exploded, and even some details about how the explosion took place. Supernova astronomers are a lot like forensic scientists dusting for fingerprints and getting DNA samples at the scene of a crime. But instead of a typical crime scene, they are investigating the death of an entire solar system. Dr. Lindsey Kwok is a CIERA fellow at Northwestern University and an expert at using JWST to perform state-of-the-art forensic supernova science.