Milky Way has gas surplus after robbing outer space 'bank accounts'

In a new report, Hubble astronomers rely on intergalactic 'fingerprints' to track gas clouds

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The sources of excess gas flowing into the Milky Way are a mystery, but scientists believe our galaxy could be robbing the gas “bank accounts” of smaller nearby galaxies, lured into the Milky Way’s gravitational pull and stripped of their resources.

Supernovas, the explosive star phenomena, and stellar winds, which send out particles from stars’ atmospheres, blast gas out of the galaxy, but that gas returns and is recycled to help form the next generation of stars.

But the Milky Way is accumulating a surplus of gas that it’s likely pulling in from elsewhere, according to a report to be published in The Astrophysical Journal.

Lead author Andrew Fox told NASA that the team from the Space Telescope Science Institute in Baltimore had expected to find the Milky Way’s “books balanced” but instead found more gas entering the galaxy than leaving.

The team analysed a decade’s worth of footage from the Hubble Space Telescope's Cosmic Origins Spectrograph to study the inflow and outflow of gas patterns.

Previously, astronomers didn’t know how to measure what’s coming in versus what was going out. Because the galaxy’s gas clouds are invisible, the team relied on light from quasars — the bright, energy-filled nuclei of far-away galaxies — to find them.

Those gas clouds absorb some of that light, leaving “fingerprints” that the team could then track. A cloud’s colour told the team whether it was leaving (red) or approaching (blue).

Future studies of the phenomenon will investigate the source of the extra gas and whether other galaxies have similar gas transactions, according to NASA.