The universe might host several stars that consume planets.
A new study suggests that a surprising number of stars, potentially one in twelve, may have devoured a planet at some point in their lifetimes, according to Space.com.
Scientists have previously found evidence of unusual element compositions in some stars, hinting at the possibility of planetary consumption. This new research strengthens that theory by examining "co-natal" stars, twins born from the same cloud of gas and dust. These twins should have nearly identical makeups, so any significant chemical differences could point to a dramatic event, like a star swallowing a planet.
The research team used data from the European Space Agency's Gaia satellite to identify 91 pairs of co-natal stars. They then analysed the light from these stars using powerful telescopes to determine their elemental compositions.
The analysis revealed a surprising fact: in about 8% of the pairs, one star showed signs of having engulfed a planet, displaying a different chemical makeup compared to its twin.
"What's truly surprising is the frequency at which it seems to happen," study co-author Yuan-Sen Ting, an astronomer at the Australian National University in Canberra, told Space.com. "It implies that stable planetary systems like our own solar system might not be the norm. This gives us a deeper perspective on our place in the universe."
While our Sun is expected to engulf some planets when it becomes a red giant in the distant future, this study focused on stars in their prime. This implies planetary ingestion might be a more frequent occurrence during a star system's normal lifespan. One possibility is that rogue planets, ejected from their own systems, could collide with other stars.
The findings suggest that many planetary systems might be less stable than previously believed, with planets potentially flung out at random. However, the researchers assure us that our own solar system seems stable on a human timescale, so there's no immediate need to worry.
The study, published in thejournal Nature on March 20th, leaves some questions unanswered. It's not entirely clear whether stars are swallowing fully formed planets or simply leftover planetary building blocks from their formation. Future research may shed light on this detail.