Space Matter: The Other Eclipse

You probably have heard quite a bit about the solar eclipse that will occur on August 21, 2017 and be visible from a good part of the continental United States. It’s a once-in-a-lifetime event for sure (except there’s another full eclipse happening in 2024 that will also be visible across much of the continental U.S., but still), and one that as many people as possible should be planning to see.

But there’s another eclipse happening in September, and a group of scientists have their eye on it. It’s not really well-known, and it might not be of interest to nearly as many people, but it’s pretty cool nonetheless.

Around 1,000 light years away, there’s a young star called PDS 110, located in the constellation Orion. It’s a pre-main-sequence star, which means that it’s still acquiring mass. The protostar, which is currently a similar temperature to but larger than our Sun, is basically sucking in as much dust and gas as it can in order to achieve sufficient mass to start burning hydrogen. At that point, it will contract (because of a higher temperature in its core) and become a main-sequence star.

1.protostars.jpg Protostars in the constellation Orion (Image credit: NASA/JPL-Caltech)

Recently, a group of astrophysicists located at the University of Warwick noticed something strange about PDS 110: Its light, as seen from the Earth, is blocked by a very large object. What’s more, the interference is predictable and regular.
With the help of other researchers around the world, the Warwick team (led by Hugh Osborn) took a close look at data from the star over the last fifteen years. This is possible through the Wide Angle Search for Planets (WASP) and the Kilodegree Extremely Little Telescope (KELT).

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WASP is a planet detection program that uses eight wide-angle cameras that monitor the sky continuously for transiting planets. What they specifically look for is changes in starlight when planets cross in front of a star; there are two WASP sites currently — one in the Canary Islands and the other in South Africa. Between these two camera setups, WASP is able to monitor millions of stars simultaneously over the long-term.

One of the two WASP telescopes (Image credit: SuperWASP)

KELT has a similar setup: two robotic telescopes, one in the United States and the other in South Africa, that constantly monitor the sky. They, too, look for changes in star light output, as seen from the Earth, that could be caused by planets in orbit of the star.

Using both sets of data, the team confirmed that there was something very large in the neighborhood of the star PDS 110. Every two and a half years, the research team noticed that the light from the star dips for a period of two to three weeks. What’s really interesting, though, is how the light acts during the eclipses. There are short, sharp changes in the light we can see from Earth; this suggests that there is something more going on here. Astronomers have theorized that the planet has a giant set of rings, much larger than those around Saturn.

This close-up image of Saturn’s rings was taken by Cassini (Image credit: NASA/JPL)

Additionally, given the characteristics and duration of the eclipse, the astrophysics team has figured out the approximate mass of the object, and it’s much, much larger than Jupiter. According to their calculations, it could have as much as 68 times the mass of the largest planet in our solar system. This may put it in brown dwarf territory.

The next transit of PDS 110 is scheduled for September 2017 — or, if you prefer, the next eclipse (because if you think about it, a solar eclipse is just the Moon transiting between the Sun and the Earth). The star is bright enough that even those with relatively basic telescopes can witness the event.

We’ve found more than one ringed planet outside our solar system, but this is notable for a few reasons. First, this would be the first planet with rings we’ve found that has an orbit that’s predictable. Second, we don’t know that PDS 110’s planet is actually out there; this is all hypothesis and conjecture based on the existing evidence that scientists have been able to find in planetary surveys. It will be exciting to see what happens once the Warwick team and their colleagues turn their telescopes on PDS 110. Who knows what they’ll find?

Top photo by NASA/Goddard

Swapna Krishna is a freelance writer, editor and giant space/sci-fi geek.