Giant ringed planet may have been spotted as it eclipses its host star

Tabby’s star, which undergoes a chaotic pattern of dimming, has attracted a lot of attention due to suggestions that it might host an orbiting mega structure constructed by aliens. But it’s not the only star with an odd pattern of dimming. Astronomers have now taken a close look at one called PDS 110 and come up with a possible explanation for its pattern: a giant planet with rings that orbits outside the plane of most of the other material in the system.

While it’s a pretty tenuous explanation, the good news is that we should be able to get more data soon. The planet’s next passage is expected to be in September, and the dimming should be clear enough to be visible to amateur astronomers.

PDS 110 lies a bit over 1,100 light years from Earth. It’s similar to our Sun in terms of mass, but it’s much, much younger; estimates are that it’s less than 10 million years old. At that age, it’s still expected to have a large disk of dust and gas that may be forming planets. But imaging of PDS 110 shows no sign of the dust, suggesting that the disk is at an angle where it doesn’t obscure any of the star from Earth’s perspective.

Since planets form in the same plane as the disk, we wouldn’t expect any of them to transit between the star and Earth. That would preclude detecting them by tracking a regular dimming of the star’s light as the planet orbits.

Yet something is dimming the light of PDS 100 in a rather significant way. The eclipse lasts for 30 days, and roughly 30 percent of the star’s light is blocked as it happens.

Researchers first saw this dimming in data taken by the WASP telescope in 2011, leading them to dive into the archives to search for other telescopes that might have imaged the star. They found data taken by the INTEGRAL space telescope, which looked at PDS 110 14 different times. And the All-Sky Automated Survey had observed the star on and off for nearly a decade. But neither of these showed anything like the 30-percent dip in brightness.

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