Half-Baked Stars and Handmade Macarons with Dr. Theron Carmichael

What is a transiting brown dwarf, why are they so rare, and how do you find them? Equally important, how do you make a good French macaron? To find out, Dr. Charles Liu and co-host Allen Liu welcome astronomer and astrophysicist Dr. Theron Carmichael.

As always, though, we start off with the day’s joyfully cool cosmic thing: a recent paper in the Astrophysical Journal possibly linking a supernova that took place millions of years ago and bombarded Earth with cosmic rays and radioactive iron with a flurry of virus mutation that took place in deep ancient lakes on our planet. After Theron brings up the Chicxulub meteor impact (the one that spelled trouble for dinosaurs) and how astronomical events can affect the evolution of life here on Earth, we naturally turn to the effects of extreme radiation events and… the mighty Marvel mutants themselves, the X-Men!

Then it’s time to talk about Dr. Carmichael’s bread and butter: detecting and categorizing transiting brown dwarfs, an exceedingly rare form of the “failed stars” which actually orbit other stars. Theron explains that while we know how stars and planets form, we don’t exactly understand the formation of brown dwarfs, which exist in the gray region between a star and a planet. Allen reminds us how protoplanetary discs form, while Theron points out that the distinctions may not be as clear as we used to think.

Our first student question comes from Ani, who asks, “There are a lot more small, faint stars than big bright stars. Does that mean there are a huge number of brown dwarfs in the galaxy?” Yes, according to Dr. Carmichael. And not only are there more of them, but Theron explains that they last longer, too. Finding them is challenging, but it’s become easier thanks to TESS, the Transiting Exoplanet Survey Satellite mission that’s been running for over 7 years, well past its operational lifespan.

Our next student question comes from Josie, who asks, “Could there be life on brown dwarfs?” While brown dwarfs are colder than stars, they are still too hot to form and sustain the molecules we believe are necessary for life. And while those molecules are in fact present in the atmosphere of brown dwarfs – along with titanium oxide clouds – the pressure and temperature conditions of brown dwarfs make life as we know it unlikely. Theron explains that the atmospheric conditions of brown dwarfs are not dissimilar to Jupiter, as opposed to those on Jovian moons like Europa that we’re going to explore when the Europa Clipper reaches its destination in 2030.

After that, Theron tells us about the annual MIT Mystery Hunt, his long-time love of baking, and the astronomical value of macarons. (For his French macaron recipe, please visit our Patreon page.) Allen shares how he has made cookies conforming to the Einstein tile, and Charles mentions a few scientists who also love to bake. Theron explains how baking and brown dwarf research use the same parts of his brain. We even get to see a video clip of him making macarons!

To end the show, Theron tells us about the international working group he helps lead focused on learning more about transiting brown dwarfs.

If you’d like to know more about Dr. Theron Carmichael, you can follow him on Twitter/X @TherBaer or his website, www.theroncarmichael.com.

We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon.

Credits for Images Used in this Episode:

• Chicxulub impact 65 million years ago – Illustration credit: Lunar Planetary Institute/David King.
• Rendering representing the size of a Brown Dwarf compared to other celestials. – Illustration credit: NASA/ JPL-Caltech/ UCB.
• Planets forming around a young star – a protoplanetary disc. – Credit: NRAO/AUI/NSF.
• Illustration of the