It is rare that every part of an astronomy news story is so cool. You will want to stay for this.
A telescope the size of the planet has been observing a red dwarf star system for 14 years and has found a planet more massive than Jupiter in the system.
Yes. This is a story I like to tell.
The distance from Earth to the star system is 20.37 light-years, and it is a pair of red dwarfs. The more massive of the two, GJ 896A, is 0.44 times the mass of the Sun, and its companion star, GJ , is much smaller. Both are nice. They are so faint you need a telescope to see them.
The stars were observed in 2006 and again in 2020 using the very long baseline array. When they observe at the same time, their data are combined in a way that makes their vision as big as a single dish. This technique, called interferometry, has been used for decades, and is currently most famous as used by the event horizon telescope to look at the black holes in the center of the Milky Way
A telescope over 10,000 km wide is able to measure the position of an object or separate two objects in the sky with great accuracy. 60 microarcseconds is a very small angle in the sky. For example, there are 3,600 arcs in a degree, and the moon is only half a degree away. This resolution is comparable to being able to see a cell phone on the moon.
It was possible to see the motion of the two stars around each other. They are separated by 4.5 billion kilometers, the same distance as Neptune is from the sun.
It is easy to pick up the motion of the Earth around the Sun. We can see the stars from one angle and then another six months later. The idea is similar to holding your thumb in front of your face and closing your eyes at the same time. The distance to GJ 896 is well determined because of this technique.
The primary star, GJ 896A, is corkscrewing through space, making one cycle around every 284.4 days. Something tugging on the star causes it to spiral through the galaxy. It is a planet with 2.3 times the mass of Jupiter according to the astronomer.
The effects of the planet's gravity can be seen in the position of GJ 896A over time. It is very rare for a planet to be found using the method of measuring a star's position. This is the only one that has been found this way.
The star in the plane that tilted wildly to the plane of the two stars was tipped by 148. It is strange. Really strange.
All of the planets are in the same plane. Some exoplanets have been found to travel at large angles to other planets. One planet may have moved too close to another, causing it to tilt. The second star may have had an effect on the planet's tilt until it shifted to where it is now. Maybe it had something to do with how the planets and stars formed. We don't know
The planet is strange. Most of the planets around red dwarf stars are small Earth-sized planets. Only a small number of gas giants have more than twice the mass of Jupiter. It's more fun to study this system because it's so weird.
This is the first time that full three-dimensional motions of a pair of stars have been determined. This is one of the most interesting star/planet systems we know because of everything else in it. It is so close to us that we can study it in more detail.
It makes me wonder as well. You would expect the closest system to be thousands of light-years away if it were rare. The fact that GJ 896 is one of the closest star systems to the Sun in the entire universe implies that these sorts of things are commonplace. We can only find out by studying as many red dwarfs as possible. It is hoped that long-term observations will solve the mysteries of the planet and how it came to be.
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