Christian Aganze
he/him
Christian is an astrophysicist at the University of California in San Diego studying objects called brown dwarfs to learn about the factors that determine which objects ignite into stars—and which ones fail to ignite.
Highlights
Raised in Rwanda
Discovered astronomy in college, and quickly made it his career
Enjoys playing and listening to music—especially modern jazz or African music
In our own Solar System, we know that the Sun is a star and the planets are, well, planets. After all, only the Sun is a giant, glowing ball of hot plasma. But where is the actual line between “star” and “planet?” It’s somewhere between Jupiter and the Sun, but that’s a huge range—the Sun is 1000 times more massive than Jupiter!
In fact, there’s another category between “star” and “planet.” Christian Aganze, an astrophysics graduate student at the University of California in San Diego (UCSD) studies the not-quite-stars, not-quite-planets called brown dwarfs to learn about the limits of forming stars. “Brown dwarfs are interesting just by themselves, being objects that are below the hydrogen-burning limit [that makes a star a star],” Christian says. “We want to know how many of them there are, because we actually don’t know that number.” That’s because brown dwarfs are incredibly faint and hard to find—they don’t glow brightly like stars, and they’re also typically too far from other stars to reflect much light. So astronomers have only found a couple thousand brown dwarfs, and they’re all close to us—within about 300 light years (for context, the Milky Way is about 100 thousand light years across, and our nearest galaxy neighbor, Andromeda, is 2.5 million light years away).
That’s why Christian is excited for Rubin Observatory, which will help astronomers find brown dwarfs ten times farther away than the ones we can see now. And brown dwarfs are too small and faint to see in other galaxies (even with Rubin), so our Milky Way galaxy is the only place in the Universe where astronomers like Christian can study them. “Can we distinguish between brown dwarfs, which form from collapsing clouds, and planets, which form in disks around stars?” he asks. “And how does what the cloud is made of affect the number and types of brown dwarfs it can form?”
To answer these questions and understand more about how stars form, he needs to find a lot more brown dwarfs! Until Rubin comes online, Christian is confirming and studying very distant (up to 3000 light years away) candidate brown dwarfs found with the Hubble Space Telescope. But Hubble can only see a very small area of the sky at a time, so Christian also works with a citizen science project called Backyard Worlds. This project brings together thousands of volunteers to find faint, nearby objects up to 100 light years away or so in larger sky areas from NASA’s WISE mission, many of which are brown dwarfs. Once Rubin comes online, Christian and other astronomers will be able to set up their own citizen science projects to find brown dwarfs in Rubin data!
Growing up in Rwanda, Christian’s favorite classes were always science and math, and like many kids, he especially liked experiments in chemistry class. He took introductory physics in high school, but it wasn’t until his undergraduate degree at Morehouse College in Atlanta, Georgia that he learned about astronomy for the first time. While he was at Morehouse, his now-PhD advisor visited to recruit new students to study brown dwarfs, and the rest is history. Christian soon began studying brown dwarfs himself, and he’s continued that work in his PhD research at UCSD. Since he’s been there, he’s participated in a program called the LSST Data Science Fellowship, which trains astronomy graduate students in the skills needed to work with huge data sets like the one Rubin will produce.
Outside of science, Christian enjoys all things music: listening to it, going to shows, playing guitar, or learning to play piano (“I’m not very good yet”). In particular, he loves blues, modern jazz, or African music. He often goes to small concerts in town played by musicians he listens to on Spotify. In fact, he recently saw his favorite R&B / neo soul jazz band play in San Diego. Their name? Moonchild—a fitting favorite band for an astronomer! “It was meant to be,” he laughs.
Christian never thought he’d end up working with an astronomy observatory, at least not until he learned about astronomy in college. But he is where he is now because he’s let his curiosity lead the way. “Follow your passion,” he says. “Follow things that you like and do them, and see what happens because I never thought I’d be here as a kid.”
Lightning round Q&A: Get to know Christian better!
If you could have lunch with anybody, living or not, who would it be?
Albert Einstein.
If you could travel back in time to any period, what period would you go to?
I would stay here!
If you didn't have to sleep, what would you do with the extra time?
I would learn how to play the piano better. I would play music.
What is a food or a meal that you could eat for a week straight?
Tacos—I really love Mexican food.
What's your most used emoji?
The laugh-crying emoji 😂 and the one screaming a little bit 😱