What Shuts Down a Galaxy’s Star Formation?

In the 1920s, Edwin Hubble studied hundreds of galaxies. He found that they tended to fall into a few broad types. Some contained elegant spirals of bright stars, while others were spherical or elliptical with little or no internal structure. In 1926 he developed a classification scheme for galaxies, now known as Hubble’s Tuning Fork.

Hubble’s tuning fork diagram for galaxies. Credit: Edwin Hubble

When you look at Hubble’s scheme, it suggests an evolution of galaxies, beginning as an elliptical galaxy, then flattening and shifting into a spiral galaxy. While many saw this as a reasonable model, Hubble cautioned against jumping to conclusions. We now know ellipticals do not evolve into spirals, and the evolution of galaxies is complex. But Hubble’s scheme marks the beginning of the attempt to understand how galaxies grow, live, and die.

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A Stellar Stream of Stars, Stolen from Another Galaxy

Modern professional astronomers aren’t much like astronomers of old. They don’t spend every suitable evening with their eyes glued to a telescope’s eyepiece. You might be more likely to find them in front of a super-computer, working with AI and deep learning methods.

One group of researchers employed those methods to find a whole new collection of stars in the Milky Way; a group of stars which weren’t born here.

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A Giant Galaxy Seen Lighting Up the Universe Shortly After the Big Bang

About 370,000 years after the Big Bang, the Universe experienced a period that cosmologists refer to as the “Cosmic Dark Ages.” During this period, the Universe was obscured by pervasive neutral gas that obscured all visible light, making it invisible to astronomers. As the first stars and galaxies formed over the next few hundred millions of years, the radiation they emitted ionized this plasma, making the Universe transparent.

One of the biggest cosmological mysteries right now is when “cosmic reionization” began. To find out, astronomers have been looking deeper into the cosmos (and farther back in time) to spot the first visible galaxies. Thanks to new research by a team of astronomers from University College London (UCL), a luminous galaxy has been observed that was reionizing the intergalactic medium 13 billion years ago.

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Astronomers See Through the Milky Way’s Dust to Track Where Radiation is Coming From at the Center of the Galaxy

The center of our very own galaxy might be one of the Universe’s most mysterious places. Astronomers have to probe through thick dust to see what’s going on there. All that dust makes life difficult for astronomers who are trying to understand all the radiation in the center of the Milky Way, and what exactly its source is.

A new study based on 20 years of data—and a hydrogen bubble where there shouldn’t be one—is helping astronomers understand all that energy.

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Complete and Total Mayhem in a Distant Galaxy Collision

A cluster of galaxies is nothing trivial. The shocks, the turbulence, the energy, as all of that matter and energy merges and interacts. And we can watch all the chaos and mayhem as it happens.

A team of astronomers are looking at the galaxy cluster Abell 2255 with the European Low-Frequency Array (LOFAR) radio telescope, and their images are showing some never-before-seen details in this actively merging cluster.

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Hubble Looked as Far Back in Time as it Could, and Still Couldn’t See the First Generation of Stars in the Universe

Astronomers don’t know exactly when the first stars formed in the Universe because they haven’t been observed yet. And now, new observations from the Hubble Space Telescope suggest the first stars and galaxies may have formed even earlier than previously estimated.

Why? We *still* haven’t seen them, even with the best telescope we’ve got, pushed to its limits.

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Astronomers Find the Source of the Huge Bubbles of Gas Flowing Out of the Milky Way, Still No Idea What Caused Them

There’s an unusual paradox hampering research into parts of the Milky Way. Dense gas blocks observations of the galactic core, and it can be difficult to observe in visible light from our vantage point. But distant galaxies don’t always present the same obstacles. So in some ways, we can observe distant galaxies better than we can observe our own.

In order to gain a better understanding of the Galactic Center (GC) and the Interstellar Medium (ISM), a team of astronomers used a telescope called the Wisconsin H-Alpha Mapper (WHAM) to look into the core of the Milky Way in part of the optical light spectrum.

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