85757065

Photo by: MARK GARLICK/SPL

MARK GARLICK/SPL

A Eulogy for a Galaxy

ID2299, a galaxy 13.8 billion light years away, died far too young.

March 05, 2021

The galaxy ID299–known affectionally to many as “Idee” – passed away when the universe was only 4.5 billion years old, a mere third of its present age. Idee should have been among the great galaxies to inhabit the present-day universe, but fate intervened in the form of another massive galaxy, which crashed into Idee, and deprived it of all its star-forming material.

But we come together today to celebrate the life that Idee lived and remark on its accomplishments. According to the latest observations taken with the Atacama Large Millimeter-Submillimeter Array (ALMA, perhaps the most powerful telescope currently in operation on Earth), Idee is currently ejecting over 10,000 suns worth of material every single year.

It has already lost nearly half of its molecular gas, the crucial ingredient needed to make new stars.

Astronomers suspect that Idee suffered a fatal accident. Most galaxies in our universe are racing away from each other, carried by the ceaseless invisible currents of the expansion of the cosmos. But occasionally they get too close and become gravitationally attracted, and, over the course of hundreds of millions of years, collide.

Galaxy collisions are some of the most violent, energetic events to occur in the universe, and they rarely turn out well for their participants, including Idee.

The amount of gravitational forces unleashed during a galaxy collision is almost unfathomable. They can literally tear a galaxy apart, raising so-called “tidal tails”, which are long streams of gas and stars that get flung out of a galaxy during the collision. The physics behind it is the same physics that explains the tides on the Earth, hence the name. When a galaxy gets too close to another, the side nearest the approaching interloper experiences an extra-strong gravitational tug. But on the opposite side, the lack of gravity causes bits to float away.

This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of its gas being ejected by a “tidal tail” as a result of the merger. New observations made with ALMA, in which ESO is a partner, have captured the earliest stages of this ejection, before the gas reached the very large scales depicted in this artist’s impression

This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of its gas being ejected by a “tidal tail” as a result of the merger. New observations made with ALMA, in which ESO is a partner, have captured the earliest stages of this ejection, before the gas reached the very large scales depicted in this artist’s impression

Photo by: ESO/M. Kornmesser

ESO/M. Kornmesser

This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of its gas being ejected by a “tidal tail” as a result of the merger. New observations made with ALMA, in which ESO is a partner, have captured the earliest stages of this ejection, before the gas reached the very large scales depicted in this artist’s impression

The moon raises tides on opposite sides of the Earth, and a massive galaxy can stretch and distort another.

Such a fate seems to have befallen unfortunate Idee.

Galaxies are full to the brim with gas, but most of it is unusable for making stars. To manufacture a sun, you need to compress a lot of material into a very small enough tight enough to trigger nuclear fusion. And in order to compress gas into a small volume, you need to make it cold. If the gas is too hot, it just spends all its time flying around without ever settling down.

That’s why what’s happening to ID2299 is so alarming. The tidal disruption event it suffered during its encounter with the neighboring galaxy ripped away its own star-forming gas and sent it flying into intergalactic space. Idee is especially losing the cool component of its material, which is exactly what it needs to make stars. Soon enough, star formation in that galaxy will completely shut down. It will still shine for billions of years more, but that will be from the light of already-formed stars, not new ones.

Over time, Idee will entirely fade from the cosmic scene.

Idee will be missed.

Paul M. Sutter

Paul M. Sutter is an astrophysicist at Stony Brook University and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of How to Die in Space.

Next Up

A Guide to this August’s Best Astronomy Attractions

Learn more about the exciting things happening in the night sky this month! From the rings of Saturn to the most popular meteor shower of the year, August 2022 has us stargazing all month.

What We’ve Already Learned From James Webb? (Hint: it’s a lot)

That was worth the wait. Just a quick handful of months since its historic launch on Christmas Day, the James Webb Space Telescope has flown to its observing position, unfolded its delicate instruments and ultra-sized mirror, and run through a suite of checks and alignments and calibrations. The team at NASA behind the telescopes released their first batch of images from the science runs, and besides being gorgeous, they're powerful.

There’s a Hole in Our Galaxy

Folks, we just found a 500-lightyear-wide hole in our galaxy. Fess up: which one of you did it?

2020: A Year of Big Leaps for Mankind

Here are a variety of some amazing space launches to look forward to in 2020.

How Astronomers Use a Trick of Gravity to See the Most Distant Objects in the Universe

Let’s say you’re an astronomer (work with me here) and you want to take a picture of something incredibly, deeply far away. You know, the typical business of astronomy.

NASA and SpaceX are Going on a Date, and We're All Invited

Save the date--On May 27th, if everything goes as planned, a rocket will launch from Kennedy Space Center in Cape Canaveral, Florida. Watch SPACE LAUNCH LIVE: AMERICA RETURNS TO SPACE on Discovery and Science Channel starting at 2P ET.

This Year, James Webb will Take a Close Look at a Lava World

The James Webb Space Telescope is gearing up to be an exoplanet extraordinaire. Among many other missions and targets, astronomers plan to use the observatory, now in its final stages of preparations to study…well, a world where it might rain lava.

Will a Colony on Mars Ever Be Feasible?

We’ve all seen the movies. Tunnels cut through the red rock. Giant glass domes stretching from one end of a crater rim to another. Hydroponics. Lots and lots of hydroponics. But Mars is… a challenge.

How to Make a Neutron Star at Home

First, take a bunch of matter. It doesn’t matter what kind – a piece of paper, some leftover gum. Then, press it, and press it, and press it some more. Don’t stop now! We’ve got a long way to go.

Why Astronomers Care About Super-Old Galaxies?

A long time ago, our universe was dark.It was just 380,000 years after the big bang. Up until that age, our entire observable cosmos was less than a millionth of its present size. All the material in the universe was compressed into that tiny volume, forcing it to heat up and become a plasma. But as the universe expanded and cooled, eventually the plasma changed into a neutral gas as the first atoms formed.

Related To: