Our sun is a slowcoach, but that may have helped our solar system blossom

10 Apr 2015

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Artist's hypothetical view of night sky within a young Milky Way-like galaxy 10 billion years ago. Via NASA/ESA/Z. Levay (STScI)

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NASA has worked out that our sun took ages to get its act together but, by waiting for other galaxies to smash onto the scene before smashing out quite explosively, it capitalised on their abundant life-giving properties.

In an incredibly comprehensive Multi-Observatory Galaxy Survey, astronomers looked at rival galaxies of the same ilk as the Milky Way, and how they underwent a stellar baby boom.

This ‘boom’ saw these galaxies spray out stars like nobody’s business, about 30 times faster than today.

The Milky Way did such, peaking 10bn years ago. But our sun only woke up 5bn years ago, emerging after the surge had long since ended.

It wasn’t easy to find galaxies comparable to the Milky Way as a means of comparison, with astronomers delving through 24,000 of them before finding what they were after.

That constitutes all the catalogues of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, taken with Hubble, and the FourStar Galaxy Evolution Survey, made with the Magellan telescope.

It turns out our sun used all its genius to wait until the last moment before revealing itself, as the now long-gone rival solar systems had broken up and dispersed throughout space.

Hubble Milky Way

Hubble snapshots show how galaxies similar to our Milky Way evolved over time. Via NASA/ESA/C. Papovich/H. Ferguson/S. Fabe

That changed the whole dynamic of our pocket of space; elements heavier than hydrogen and helium were more abundant later in the star-forming boom as more massive stars ended their lives early.

They subsequently enriched the galaxy with material that served as the building blocks of planets and even life on Earth.

Astronomers managed to look back in time by viewing rival galaxies far away in the distance, which are at different evolutionary stages now but, as light takes a while to get to us from them, we’re essentially seeing their state from billions of years ago.

“This study allows us to see what the Milky Way may have looked like in the past,” said Casey Papovich, lead author of the paper on the topic.

“It shows that these galaxies underwent a big change in the mass of their stars over the past 10bn years, bulking up by a factor of 10, which confirms theories about their growth. And most of that stellar-mass growth happened within the first 5bn years of their birth.”

The images are pretty incredible, and bring to mind this gem of a Don McLean hit. Do enjoy.

Gordon Hunt is a journalist at Siliconrepublic.com

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