The tiniest galaxies of all are the most susceptible to violence by their larger, bullying siblings. That’s why we need them in isolation.
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.
Key Takeaways
-
All throughout the Universe, galaxies grow in two main ways: by merging with other galaxies and by accreting matter, slowly, from the intergalactic medium. -
Nearby, we find large numbers of tiny galaxies, but they’re all the victims of bullying: having been influenced by larger, more massive neighbors like Andromeda and our own Milky Way. -
If we want to know how these tiny galaxies, the most abundance in the Universe, grow up, we need to find them in isolation. That’s exactly what our guest, Dr. Catherine (Cat) Fielder, specializes in!
Sign up for the Starts With a Bang newsletter
Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all
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!
Sign up for the Starts With a Bang newsletter
Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all
The Universe is expanding, and individual, bound structures are all receding away from one another. How, then, are galaxies still colliding?
From the tiniest subatomic scales to the grandest cosmic structures of all, everything that exists depends on two things: charge and mass.
The CMB gives us critical information about our cosmic past. But it doesn’t give us everything, and galaxy mapping can fill in a key gap.
Ring galaxies are rare, but we think we know how they form. A new, early-stage version, the Bullseye galaxy, provides a new testing ground.
Here in our Solar System, terrestrial bodies get moons from gravitational capture or collisions. The Pluto-Charon system? It was both.
When your life’s truth and the reality you live become out of sync, you risk falling into an “anxiety spiral.”
