Warm Cloud of Debris Indicates Relatively Recent Collision Between Exoplanets

Until today, astronomers have discovered more than 4,000 exoplanets residing in the cosmos, rotating around their stars. But if they are even slightly similar to our own Solar System, they are likely to have violent histories where exoplanets collided with each other, producing dusty debris. Now, researchers have discovered evidence of such a catastrophe that took place not long ago.

The location of the terrific accident is a system known as BD +20307, which sits more than 300 light-years from Earth. There are two stars, each of them boasting more than one billion years of age, which orbit each other in a rather close vicinity. The evidence for the fatalistic event is a cloud of debris that is still warm.

Evidence of the Impossible

It is rather common for stars to be surrounded by clouds of debris. Even our sun has several: the asteroid and Kuiper belts. These are theorized to be pieces and leftover dust from clashes between a number of ancient planets, but after being in space for approximately 4.5 billion years, today they are extremely cold.

Considering that the two stars located in BD +20 307 are more than a billion years old, any leftover clouds there should be really cold by now. Despite that, infrared monitoring made by the Spitzer Space Telescope 10 years ago brought evidence that the dust was still warm. The observations suggested that an extensive planetary clash must have taken place in the system relatively a while ago.

Now, the evidence has grown stronger, as new observations by NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) were analyzed. The team in charge found that the Infrared brightness of the debris has increased by approximately 10 percent since the prior assays, suggesting there is more warm debris in the cosmos than there was ten years ago.

An artist’s impression of a planetary collision in the system BD +20 307 [Image: NASA/SOFIA]
“The warm dust around BD +20 307 gives us a glimpse into what catastrophic impacts between rocky exoplanets might be like,” says Maggie Thompson, lead author on the study. “We want to know how this system subsequently evolves after the extreme impact.”

The team of astronomers believes that there are other potential explanations for why the dust might be even more brighter now than a decade ago. The clouds could have wandered in the vicinity of the stars, or might just be riveting more heat than earlier.

However, these explanations would be improbable in the space in just ten years, which is similar to a blink of an eye for us, but on a cosmic level. The astronomers intend to follow up with a couple more observations and continue studying the information they receive in case other changes happen in the system.

The study was published in the Astrophysical Journal.

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