Galaxies have hidden objects: they don't emit enough light, so they're hard to observe.
The gas that the team studied is inthe expanded disk of galaxies, this region is also called the region "near-galactic environment". Galaxies like the Milky Way have stellar disks up to 200,000 light-years across.
This gas does not emit enough light toobserve it, so scientists previously decided to study it in a different way: they used a bright quasar located behind the galaxy being studied. Next, they measured the quasar's light and then determined how much it was absorbed by the gas around the galaxy.
However, in the new study, the team usedrelatively new technique. Based on data from the Hubble Space Telescope and MMT Observatory, they analyzed light from a background galaxy (not a quasar) to obtain measurements. This allowed them to estimate the size of the gas cloud.
The research team hopes that future projects will use this new technique to study galaxies using the next generation of telescopes.
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