(NewsNation) — In a development that might better explain how planets form around stars, astronomers have found that some stars might not have the right ingredients to make certain types of planets, especially larger versions of Earth called “super-Earths.”

Scientists used to think that all stars could form planets, just fewer of them if they had less metal. But this new study shows that there might be a point where stars with very little metal can’t form super-Earths at all.

Earlier this year, NASA announced the discovery of a super-Earth 137 light years away that’s positioned in its solar systems’ “habitable zone,” where life could be capable of forming and surviving.

The research team looked at 10,000 stars with very little metal using a special NASA satellite called TESS. Expecting to find around 70 super-Earths around these stars, they found none.

Super-Earths are larger than Earth but smaller than massive planets like Neptune. They can be rocky, gaseous, or a combination of both.

This discovery suggests that super-Earths didn’t start forming until the universe was about half its current age, around seven billion years ago. Before that, there weren’t enough metals in stars to make these planets.

The discovery may help scientists understand when and where planets like super-Earths can form in our galaxy, and help astronomers focus their search for planets around stars that are more likely to have them. This could help in the ongoing search for potentially habitable worlds beyond our solar system.

The research, led by Ohio State University astronomer Kiersten Boley, was published in The Astronomical Journal.