A Crumbling Planet Has Been Found 140 Light-Years From Earth, Leaving A Comet-Like Tail Of Debris In Its Wake
About 140 light-years from Earth, there is a planet that is rapidly disintegrating. The crumbling world is roughly the mass of Mercury, although it orbits 20 times closer to its star than Mercury does to the sun. It completes an orbit every 30.5 hours.
Since the planet is in such close range to its star, it is likely covered in magma that is boiling off into space. A large amount of minerals on its surface is evaporating as it circles its star.
A team of astronomers from MIT discovered the planet using NASA’s Transiting Exoplanet Survey Satellite (TESS), which monitors the nearest stars for transits, or occasional dips in starlight that could signal orbiting exoplanets.
A peculiar transit alerted the astronomers to the tightly orbiting rocky planet that is leaving behind a comet-like tail of debris in its wake.
“The extent of the tail is gargantuan, stretching up to nine million kilometers long, or roughly half of the planet’s entire orbit,” said Marc Hon from MIT’s Kavli Institute for Astrophysics and Space Research.
The planet appears to be disintegrating at a rapid rate, shedding an amount of material that equates to the size of Mount Everest every time it orbits its star. The researchers predict that the planet will completely disintegrate in about one to two million years.
The new planet, called BD+05 4868 Ab, was detected by accident. The astronomers had not been looking for this type of planet at all. The discovery was made when an unusual signal was spotted.
Evidence of an orbiting exoplanet is typically represented by a brief dip in a light curve. It repeats regularly, indicating that a planetary body is passing through and temporarily blocking the light from its host star. However, the host star BD+05 4868 A, located in the constellation of Pegasus, did not follow this pattern.
A transit appeared every 30.5 hours, but the brightness took a lot longer to go back to normal, which suggested that a long, trailing structure was still blocking starlight.
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Furthermore, the depth of the dip changed with each orbit, so whatever was passing in front of the star was not always the same shape or blocking the same amount of light.
“The shape of the transit is typical of a comet with a long tail except that it’s unlikely that this tail contains volatile gases and ice as expected from a real comet—these would not survive long at such close proximity to the host star,” Hon said.
“Mineral grains evaporated from the planetary surface, however, can linger long enough to present such a distinctive tail.”
The team estimates that the planet is around 3,000 degrees Fahrenheit. Any minerals on its surface are probably boiling away into space, where they cool into a long tail.
Its low mass is leading to its demise. Massive planets like Earth have a stronger gravitational pull and can hold onto their atmospheres. This smaller planet has very little gravity and is unable to retain its mass.
The study was published in The Astrophysical Journal Letters.
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