The Sun's Possible Long Lost Twin
There's a strange sphere of mass at the outer reaches of solar space. Did another star help put it there?
Category
🤖
TechTranscript
00:00Our Sun might have a long-lost twin in the Milky Way. We'll never find it, but the evidence for it could be all around us.
00:12Our solar system is surrounded by something called an orb cloud, a vast region full of ice and debris
00:19that's much bigger than the region that includes all the planets. It extends halfway to the nearest star.
00:25It has a hundred billion objects in it, researchers think.
00:30But the orb cloud is sort of difficult to explain.
00:33All of the planets and most of the asteroids in our solar system
00:37basically exist on a single disk, a flat plane, and the reason for that is that they formed out of a disk-shaped cloud.
00:44So they're all kind of on a line with each other.
00:48But the orb cloud isn't on that plane. The orb cloud is a sphere, and we know it's a sphere
00:53because the evidence for it is all the comets that come out of the orb cloud and into our solar system, and they come in
00:59from just all sorts of directions.
01:02But there's no good way, based on models of how our solar system formed, to really explain
01:08how all those objects got there and got into that arrangement.
01:12Avi Loeb, a researcher at Harvard University known for wild and exciting ideas about how space works,
01:18wrote in a new paper with his student Amir Suraj that that orb cloud, that vast sphere, that mysterious vast sphere full of stuff
01:26we can't explain, might be a footprint of a long-lost binary twin of our Sun.
01:31Now, binary stars are pretty common in space. Two stars
01:35just form together or get captured by one another and end up orbiting around each other, orbiting a common point between them.
01:42And if our Sun had a binary twin when it was born in this birth cluster full of stars that gave birth to our Sun and many other objects and would have been full of stuff,
01:54working together, their gravity would have done a much better job of collecting debris into an orb cloud around each star.
02:03At least that's what Loeb says. Now, we don't know for sure if this binary twin existed,
02:08but Loeb said it would do a much better job of
02:12explaining the orb cloud than any models of how our solar system evolves that just have the Sun by itself.
02:20The good news is that there's actually a way to test whether this is true.
02:24One of the reasons that Loeb began wondering about this is a lot of scientists believe that there's actually a ninth
02:31undetected planet in our solar system, drifting somewhere way out beyond Neptune,
02:35deep in the solar system, in the region of the orb cloud. And the reason
02:41scientists think this is that objects beyond Neptune are sort of clustered as if there's some sort of tugboat out there
02:48pulling them into formation with gravity. Now, if that's true, if there's a big heavy planet out there, and it would be pretty heavy,
02:56I just think it has like five to ten times the mass of the Sun,
03:00then that's even harder to explain. How did a planet get out there so far beyond the disk that formed all the other planets?
03:07And
03:09Loeb said that if the binary hypothesis is true, then planet nine didn't originate in our solar system.
03:16It probably originated somewhere in the cluster of stars where a Sun was born, and our Sun, working together with its binary twin,
03:24might have captured it.
03:25But it wouldn't have just captured planet nine. It would likely have captured many, many other dwarf planets.
03:31You know, small planets that don't quite reach the full planet classification,
03:36but are on the size of Pluto, or Ceres, or these objects we do see around our solar system.
03:42And if there are lots of dwarf planets out there in the orb cloud,
03:45there's really no way our Sun could have done that on its own. It would have needed a binary twin, at least according to Loeb, to
03:53capture such a wide array of planets. Right now, planet nine has not been directly detected, and there's no evidence
04:00for these other dwarf planets. But Loeb said that future telescopes, particularly a telescope called the
04:06LSST, that are coming online in the next few years, that are going to do a really good job of doing big scans of the sky,
04:14might be able to detect not just planet nine,
04:17but also these other dwarf planets, these dim, dim points of light drifting in this vast region of space.
04:23And while that wouldn't a hundred percent prove that our Sun had a binary twin, it would be very strong suggestive evidence.
04:30So right now,
04:32have we proved that there's a twin? No. Do we know where it went? No.
04:37But probably another star came by and knocked it out of orbit with our Sun, and we'll probably never find it.
04:43So much time would have passed, billions of years, since our Sun lost its twin.
04:48They're probably in totally different parts of the Milky Way at this point, Loeb said.
04:52But we might be able to show that it was once there.
04:55That's pretty cool.