This Star Has 'Eaten' Some of Its Planets, Earning the Nickname 'Death Star'

Researcher discover evidence of in-falling planets by observing large amounts of lithium and other metals in stellar atmosphere.

Dec 18 2016, 10:00pm

Image: Gabi Perez / Instituto de Astrofísica de Canarias

We fortunately have a pretty good relationship with our sun. It largely does its own thing and we do ours, and we keep a healthy distance away from each other. Other solar systems, though, apparently aren't so lucky.

Consider HIP68468, a roughly 6-billion-year-old star that's about 300 light years away and practically a twin of our own sun. According to a recent article in the journal Astronomy & Astrophysics, the available evidence suggests it "ate" one or two of its surrounding planets, thus earning it the timely nickname of the "Death Star." And considering the many similarities of HIP68468 to our own sun, the situation raises the question of whether such a fate could happen to us.

Using the 3.6-meter telescope at Chile's La Silla Observatory, the researchers came to their conclusion by observing that HIP68468 has more than four times the amount of lithium it should have for its age, in addition to more heat-resistant metals that you normally find in rocky planets such as our own. Lithium in particular doesn't fare well in the hot core of a sun, but it thrives on rocky planets like Earth that lack the power to consume it as it forms. Thus it sticks out like a sore thumb when astronomers study the composition of a star's atmosphere.

Or take it from Debra Fischer, a professor of astronomy at Yale University, whole provided another comparison in a statement issued by the University of Chicago:

"It's as if we saw a cat sitting next to a bird cage," she added. "If there are yellow feathers sticking out of the cat's mouth, it's a good bet that the cat swallowed a canary."

The study was the product of an extensive multi-year survey of over 60 other "solar twins." Much current thought about how solar systems form is naturally based on observations of our home system, and the goal of the project is to study stars similar to the sun in order to find similarities and differences in the hopes of producing more accurate development models. So should we be worried?

"It doesn't mean that the sun will 'eat' the Earth any time soon," said Jacob Bean, a co-author of the paper and an assistant professor of astronomy and astrophysics at the University of Chicago. "But our discovery provides an indication that violent histories may be common for planetary systems, including our own."

Considering HIP68468's similarities to the sun (and thus its relative stability), it's possible the planets were knocked in by some other force—perhaps disrupted orbits that sent them hurtling into the star.

But it's long been understood that the sun will likely devour Mercury, Venus, and us as it starts to die and swell into a red giant around 5 billion years from now. Earth would likely stay out of the range of the swell, but it wouldn't count for much since it would be so close that it'd get vaporized in the intensely hot stellar atmosphere in around 7.6 billion years.

We'll likely be long gone. The sun's red giant phase may be comfortably in the future, but it's nevertheless been steadily getting brighter for long time now. In roughly 1.5 billion years, the resulting radiation will make it impossible for anything for virtually anything to live on Earth, leaving our green and blue marble a lifeless, barren husk floating in the void. Happy holidays!