Register for an account

X

Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.

X

Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

The Sciences

The Lives of the Galaxies

Astronomers gained new insights into the life cycles of galaxies.

galaxy_lives.jpg
NASA/ESA/S. Toft (Niels Bohr Institute)/A. Feild (STScI)

Newsletter

Sign up for our email newsletter for the latest science news

life_of_galaxies.jpg
This artist's concept illustrates the two types of spiral galaxies that populate our universe: those with plump middles, or central bulges (upper left), and those without them (foreground). | NASA/JPL-Caltech

If you’d never met a human, figuring out that babies and seniors are the same species might not be easy. Astronomers have to make such leaps all the time, matching snapshots of youthful galaxies with mature counterparts and filling in missing links.

Take the universe’s most massive galaxies — blobby, indistinct ellipticals. Until this year, no one understood how they got so gargantuan. But in January, astronomers used optical and infrared telescopes to look back nearly to the beginning of the universe, just 1.5 billion years after the Big Bang, where they saw newborn ellipticals — ancient galaxies so dusty they’re nearly invisible. In their early years, these galaxies formed stars a thousand times faster than the Milky Way does today, eating through their initial gas reserves in just 40 million years. After that, they grew slowly by mating with other galaxies, eventually snowballing into today’s mature elliptical galaxies.

galaxy_lives.jpg
NASA/ESA/S. Toft (Niels Bohr Institute)/A. Feild (STScI)

Now, 10 billion years later, they don’t make new stars at all. Full of old, rose-colored suns, they are “red and dead.” Theorists thought they’d become barren in their old age, lacking the cool gas that condenses into new stars. But in February, another team of astronomers discovered that some have plenty of cold gas — they just can’t use it. These galaxies’ supermassive black holes work against them, devouring nearby gas and exhaling powerful jets that either heat the remaining cold material or push it out of the galaxy entirely.

But not all the news this year focused on ellipticals; spiral galaxies showed up, too. This branch of the galactic family comes in different shapes: Some spirals have flat disks, while others are fat. In February, a third team of astronomers discovered the lifestyle difference: spin speed. As with pizza dough, the faster you twirl it, the thinner the crust becomes. Our own svelte galaxy spins at a speedy 600,000 mph.

Disks thin out or don’t, stars form or don’t, and galaxies grow gigantic but geriatric. As any astro-anthropologist would attest, making sense of our galaxy requires making sense of others that are younger, older, fatter, thinner and differently hued.

2 Free Articles Left

Want it all? Get unlimited access when you subscribe.

Subscribe

Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 70%

Subscribe

Already a subscriber? Register or Log In