Strong winds that can heat or even blow away a galaxy’s gas (like a snowplow breaking up snow) have been observed to blow up more than a hundred normal galaxies, altering the course of their evolution.

So-called galactic winds have been observed before, originating from wildly large numbers of star-forming quasars, or “stars” of the galaxy. A classic example is the star galaxy Cigar (Messier 82) in the constellation Ursa Major, which can be clearly seen ejecting large filaments of gas from its core. Winds can arise from radiation from many hot, massive stars and can be amplified by explosion waves when these dying stars explode as supernovae. Wind consists of a flow of charged particles and entrained hot and cold gases.

These galactic winds blow across tens of thousands of light-years and can heat and expel gas from the galaxy that would otherwise be used for further star formation. Astronomers call this process “feedback”; When star formation gets too intense it can actually shut down due to winds.

But so far, galactic winds have not been observed in calmer, “normal” countries. galaxies The winds in these galaxies are much more dispersed and less intense than in starburst galaxies, making them difficult to identify.

But a team led by Yuchen Guo of the University of Lyon in France set out to find these winds in ordinary galaxies. They observed more than 100 large normal galaxies about 7 billion light-years away with the multi-unit spectroscopic probe MUSE on the Very Large Telescope at the European Southern Observatory in Chile.

Because wind is so difficult to detect, Guo’s team used the strong emissions associated with magnesium atoms as a proxy. Magnesium is formed in supernova explosions and is carried away by gusts of galactic wind; This allows astronomers to use it to track the wind. Observations showed that each of the galaxies in the study sample had a galactic wind in the form of two cone-shaped bipolar streams extending above and below each galaxy for 30,000 light-years.

The obtained data show that feedback from galactic winds operates in all normal large galaxies, including the Milky Way. By doing this, they can somewhat control the rate of star formation in these galaxies. This is because molecular hydrogen clouds must be extremely cold, less than 10 degrees above absolute zero, for the gravitational collapse necessary for star formation to begin. The galactic wind can blow through these gas clouds, heating them beyond their ability to form stars and, if strong enough, even blowing the gas out.