The sun may have formed because a small galaxy passed by the Milky Way

By Leah Crane

NASA, ESA, and The Hubble Heritage Group STScI/AURA

A cramped galaxy called Sagittarius has been shaping the Milky Device for billions of years. Every time it has passed shut to our galaxy, it has precipitated sizable bursts of indispensable person formation that will also be accountable for the birth of the sun.

Tomás Ruiz-Lara at the Astrophysics Institute of the Canary Islands in Spain and his colleagues examined data from the Gaia house telescope to measure the ages of stars within about 6500 mild years of the picture voltaic system.

They found three sessions of elevated indispensable person formation, going down about 5.7, 1.9 and 1 billion years ago, as properly as hints of one other episode of indispensable person formation all around the last 70 million years that looks to mild be occurring this day. The timing of these episodes suits up with when simulations existing that the Sagittarius dwarf galaxy, which orbits the Milky Device, passed at a distance of 26,000 mild years away.

“You can comprise the Milky Device in equilibrium, mostly silent, after which when Sagittarius passed it used to be cherish throwing a stone in a lake,” says Ruiz-Lara. “It created these ripples in the galaxy’s density, so some areas turned extra dense and commenced forming stars extra effectively.”

Even though Sagittarius is somewhat cramped – now not as much as a tenth the scale of the Milky Device – it looks to comprise had an outsized comprise on the formation of stars here. Even our private picture voltaic system would perhaps simply owe its existence to the predominant shut run about 5.7 billion years ago.

“Perchance with out Sagittarius the picture voltaic system wouldn’t exist,” says Ruiz-Lara. The timing works out, he says, nonetheless there is not such a thing as a technique for us to clutch for obvious.

These passes are doubtless to continue occurring an increasing form of in most cases as Sagittarius’s orbit around the Milky Device will get tighter. “It’s getting nearer and nearer, runt by runt over time, and in the crash it’ll merge with the Milky Device,” says Ruiz-Lara.

Journal reference: Nature Astronomy, DOI: 10.1038/s41550-020-1097-0

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