Mysterious, ultraheavy stars are gobbling up atmospheres like carrion, new study hints

A strange type of ultraheavy star grows massive by feeding on the bloated, dying body of its companion, new research confirms.

While astronomers have long suspected that these "barium stars" — named for their unusually high levels of the heavy element barium — come from feeding on material from a companion, now they've finally caught these stellar leeches in the act.

Astronomers William P. Bidelman and Philip Keena first discovered the stars in 1951 after noticing high levels of barium in their atmospheres. All stars are made almost completely of hydrogen and helium, but they contain small traces of heavier elements such as barium.

Barium stars are on another level. In addition to barium, they contain large amounts of other heavy elements that are forged in one particular way, known as the s-process.

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Astrophysicists already knew that the s-process happens inside large stars near the ends of their lives when neutrons slam into light elements like helium and hydrogen, triggering them to fuse into heavier ones like carbon, strontium and barium.

But barium stars themselves aren't always near the ends of their own lives, so they couldn't have formed these elements on their own. In a paper published to the preprint database arXiv Sept. 4, astronomers confirm that these oddball heavy stars are cosmic leeches.