Cosmic dust, planets and maybe even life appeared earlier than we thought

Dust can ruin everything from nasal passages to high-tech electronics. But cosmic dust is arguably the cradle and root of everything we see — from the planet we inhabit to all the life we ​​have access to. However, recent observations with the European Southern Observatory’s Very Large Telescope (VLT) have revealed how quickly dust formed in the earliest universe.

In a paper published earlier this spring in the journal Astronomy & Astrophysicsthe authors compared the interstellar medium (ISM) in galaxies at different redshifts to estimate how it changed with cosmic time.

Basically, we asked the questions: is the relative abundance of data available to produce dust grains in the ISM the same in the early universe as it is today in the present-day Milky Way, Anja C. Andersen, co-author and an astrophysicist at the Niels Bohr Institute in Copenhagen, she told me in her office.

Using mainly data from the European Southern Observatory’s Very Large Telescope (VLT) in northern Chile, the study shows that dust formation occurred much earlier in the universe than previously thought.

NASA’s Webb Space Telescope also confirms the team’s findings.

If you asked me just ten years ago, I would have said, you need the first several generations of stars and many stars to live for many millions of years before there is a lot of dust in the early universe, Andersen says. Without dust there would be no planets early on, but it turns out there are far more mundanes much earlier than expected, he says. And there seems to be enough to create an Earth-like planet within several hundred million years after the big bang, Andersen says.

This means that possible life in the universe, even intelligent life, may have had a gigantic beginning dating back to about 12 billion years ago. And cosmic dust was instrumental in all of this.

What’s in a grain of dust?

Cosmic dust consists of nano- to micron-sized particles, basically like soot in smoke, Andersen says. But in their paper, the authors note that the main elements contributing to the composition of the dust by mass are oxygen, iron, silicon, magnesium, carbon, sulfur and aluminum.

Metals formed in stars are ejected into the interstellar medium by strong stellar winds and supernova explosions and then incorporated into the next generation of stars, the authors write. While significant amounts of metals are found in neutral gas, large fractions of these metals are instead locked in dust grains, they write.

This dust, in turn, is also key to star formation, as it is an important direct coolant for star formation and acts as a catalyst for the production of molecular hydrogen, the authors note.

Supernovas give back

In a supernova, you just have a tiny fraction of the original star that ends up as a neutron star or black hole, Andersen says. Most of the material from the supernova is simply redeposited in the interstellar medium where it provides food for the next generation of stars, he says.

But how do you create so much dust so quickly?

Empty space is a terrible place to be like a grain of dust. it has little crystal structure, so it’s as vulnerable as you and me to high-energy particles, Andersen says. There are so many things that can destroy a grain of dust. The fact that we see dust means that there must be a very efficient continuous formation mechanism, because otherwise it wouldn’t exist, he says.

Planet Building

Now, given the dust seen in these early distant galaxies, I see no reason why you couldn’t assume that you could form an Earth-like planet a billion years after the Big Bang, Andersen says.

So the screen grab at the beginning of the original “Star Wars” movie that says, “A long time ago, in a galaxy far, far away…”, might not be so far from the truth.

“Ten years ago, when I gave talks, I said that maybe one of the reasons we haven’t heard from aliens is because we’re the first generation of life in the universe,” Andersen says. But now I see no reason why if alien civilizations continued, we couldn’t have an 8-billion-year-old civilization out there somewhere, he says.

As for cosmic dust itself?

It’s nice that dust exists because it’s so important to the formation of stars like the sun and to the formation of planets, Andersen says. But I’m very glad there isn’t more dust, because dust makes the universe very difficult to observe, she says. It’s a blessing that we just exist, and yet not so much that we can’t ask the big questions about what’s out there, Andersen says.