What are low-mass halos?

Low-mass halos are like tiny invisible bubbles that hold up galaxies and stars.

Imagine you're holding a big balloon full of air, it’s light and floats easily. Now think of low-mass halos as little balloons, not too full of air, but just enough to keep the stars and planets around them from floating away into space. These halos are made mostly of stuff we can’t see, like invisible ghosts of matter called dark matter.

Low-mass halos aren’t as big or strong as their bigger cousins, which are like big pillows that hold up whole galaxies. But these little ones are still important, they help keep the stars in place and let them twirl around nicely, just like how a soft pillow lets you sleep soundly without being too heavy.

Sometimes, there are so many of these tiny halos, they’re like a bunch of little pillows all working together to make space feel cozy for stars. And even though we can’t see them, scientists know they're there because of the way stars and galaxies move, it’s like seeing footprints in the sand, even if you don't see the person who made them.