Astronomers build the first-ever 3D view of the star-planet binary system

It all started with a bang.

Some 20 light-years from Earth, which is pretty close on a cosmic scale, scientists noticed a star behaving a bit oddly. Something almost imperceptibly small seemed to tug at it, forcing it to “wobble” in its stellar neighborhood, as astronomers would whimsically put it.

Ah, an exoplanet.

It was a Jupiter lookalike, to be exact, with a mass about twice as large as our solar system‘s gas giant, orbiting its star every 284 days, and a position that falls slightly closer to its star. than Venus floats from the sun. And from there, an already invigorating realization, the discovery team decided to take things to the next level – particularly because the wobbly star at hand is part of a binary star system, meaning it is one of two stars orbiting each other.

After careful analysis, these researchers hit the jackpot. They used their faint signal from an alien world to develop what they believe is the very first shot of a full 3D structure of not just an orbiting binary star system, but a planet wandering within it. .

And before we go any further, yes, you can check out a fascinating visual representation of these diagrams just below. (More technical details can be found in a document published Thursday in The Astronomical Journal).

OK, cool, what can we do with that?

As Earthlings, we’re used to living alongside our lone sun, but when calculating star populations across the universe, it seems our planet’s personal radiator is in the minority. Generally, stars prefer to travel in duos, trios and even quartets.

“Since most stars are in binary or multiple systems, being able to understand systems like this will help us understand planet formation in general,” said Salvador Curiel, of the National Autonomous University. of Mexico and first author of the new article. said in a press release. The data we get from our own corner of the cosmos isn’t really enough to understand some of the most important rules about how planets are made or how they evolve. It is always better to have a larger sample.

Going back to the binary star system we are looking at with Curiel’s 3D diagram, this particular pair, called GJ 896AD, is mostly made up of two red dwarfs – i.e. the smallest type of star and the coolest main-sequence and most common stellar kind in the Milky Way.

And what better place to start decoding the secrets of multi-star systems than with the type most prevalent in our galaxy?

At the bottom of the frame stands a yellow-orange planet representing the exoplanet studied by the scientists.  Above its horizon line you can see a small bright yellow dot representing a star and far from these two spheres is a crimson red dot representing another star.

Above a planet about twice the size of Jupiter, this artist’s design shows the star the planet orbits and that star’s binary companion in the distance.

Sophia Dagnello, NRAO/AUI/NSF

To paint a picture of what this distant realm looks like, the researchers say that the larger of the two stars, which is the one around which the exoplanet orbits, has about 44% the mass of our sun. The smallest is only about 17% of the mass of our sun. So small, so cute. Oh, and they orbit each other once every 229 Earth years, while the super-Jupiter follows an inclined orbit of about 148 degrees to the trajectories of the two stars.

“There are alternative theories for the mechanism of formation, and more data may possibly indicate which is more likely,” UNAM’s Joel Sanchez-Bermudez and study author said in the statement. “In particular, current models indicate that it is highly unlikely that such a large planet would accompany such a small star, so perhaps these models need to be adjusted.”

Thank you, very long basic table

The driving force behind this astronomical development – metaphorically and literally – is the National Science Foundation Extra Long Dashboard. This scientific mechanism consists of a network of ten observation stations spread across the United States, each containing a 25-meter radio antenna and a control building. Basically, the stations individually capture information about deep space, then connect the dots to compile a very clear representation of what’s happening in the cosmos.

In the background, there is a medium blue sky, a mountain range perpendicular to the landscape of the photo, and bushes in the foreground.  Right in the center of this scene is a giant white instrument that holds one of the VLBA's antennae.

In northern California is one of ten identical branches of the Very Long Baseline Array.


For this study, of GJ896AB, the scientists collected optical observations spanning a staggering time range: 1941 to 2017. They then called on VLBA observations taken between 2006 and 2011, and made New VLBA observations in 2020. Put it all together and you have an impressive measurement of GJ896AB’s positions over time, which can be combined into something like a stop-motion design of what this star system looks like.

“The planet is moving around the primary star in the opposite direction as the secondary star moves around the primary star,” said Gisela Ortiz-León, of the Max Planck Institute for Radio Astronomy and author of the study. “This is the first time that such a dynamic structure has been observed in a planet associated with a compact binary system that presumably formed in the same protoplanetary disk.”

“We can do a lot more work like this with the planned next-generation VLA,” said Amy Mioduszewski of the National Radio Astronomy Observatory and author of the paper. “With it, we may be able to find planets as small as Earth.”