While the Sun is very clearly a solo act nowadays, some astronomers theorize that it once had a binary companion star. Now, Harvard scientists have added weight to the idea by showing that an ancient binary solar system explains the strange structure of the Oort cloud, and possibly the hypothetical Planet Nine. Best of all, the team outlines how we could check.

The Sun was born about 4.6 billion years ago in a gigantic cloud of dust and gas. But it almost certainly wasn’t alone – if other stellar nurseries are anything to go by, then countless other baby stars would have formed around the same time. Most of them would have drifted away soon after, spreading through the galaxy.

But some scientists believe there’s evidence that the Sun had a twin long after it left the nest. Previous work has shown that many Sun-like stars are born with companions, forming binary pairs. Over a few million years or so, most drift apart to form single-star systems, while others move closer and become tighter-knit binaries. If the Sun was once half of a binary pair, it would obviously belong to the first group.

The Oort cloud is a huge ball of icy objects that surrounds the solar system at an estimated distance of between 2,000 and 100,000 Astronomical Units (AU) from the Sun. For reference, the Earth is 1 AU from the Sun, and even Pluto usually orbits at a distance of only 40 AU.

Exactly how such a cloud of objects formed so far away remains a mystery. Current thinking goes that they’re leftover crumbs from the formation of the solar system’s planets and moons, much like the asteroid belt. But that story has a few holes in it.

Instead, the team’s new hypothesis posits that Oort cloud objects were more likely passersby that were captured by the gravity of two Suns.

Interestingly, the new model also has implications for Planet Nine, a hypothetical world thought to be lurking in the dark on the fringes of the solar system. According to the team, the gravity of binary stars would have captured an abundance of dwarf planets, including potentially a larger one like Planet Nine.

https://newatlas.com/space/sun-binary-star-long-lost-twin-planet9-oort-cloud/

Crap from Brown again.

mollwollfumble said:

Crap from Brown again.

?

mollwollfumble said:

Crap from Brown again.

You don’t want to take him to town then

> Crap from Brown again.

OK. look. The very existence of the Oort could proves that there never was a twin of the Sun. And not only that, it proves that the Sun was never passed very close by another star in its long existence.

Perhaps look at it this way. Our Oort cloud is a very fragile structure. If any heavy object passed through it it would have dispersed the Oort Cloud almost entirely. That’s because stars travel relative to each other at speeds far in excess of the speed of anything in the Oort Cloud.

The magic of the Oort Cloud is not its formation, that’s very easily explained by the time required for icy drops of matter to coalesce in a gas cloud composed of hydrogen surrounding the whole solar system.

The magic of the Oort Cloud is not the similarity of some orbits of distant objects. That is also perfectly explained as objects that have started to come together but were moving so slowly that they never managed to complete the process before the hydrogen dispersed.

The magic of the Oort Cloud is that it has remained completely undisturbed to the present day. That is actually a low probability item. I did once calculate the probability and from memory it came out in the rough ballpark of 10%.

mollwollfumble said:

> Crap from Brown again.

OK. look. The very existence of the Oort could proves that there never was a twin of the Sun. And not only that, it proves that the Sun was never passed very close by another star in its long existence.

Perhaps look at it this way. Our Oort cloud is a very fragile structure. If any heavy object passed through it it would have dispersed the Oort Cloud almost entirely. That’s because stars travel relative to each other at speeds far in excess of the speed of anything in the Oort Cloud.

The magic of the Oort Cloud is not its formation, that’s very easily explained by the time required for icy drops of matter to coalesce in a gas cloud composed of hydrogen surrounding the whole solar system.

The magic of the Oort Cloud is not the similarity of some orbits of distant objects. That is also perfectly explained as objects that have started to come together but were moving so slowly that they never managed to complete the process before the hydrogen dispersed.

The magic of the Oort Cloud is that it has remained completely undisturbed to the present day. That is actually a low probability item. I did once calculate the probability and from memory it came out in the rough ballpark of 10%.

FROM the same article:

>>It’s an interesting story, but what evidence is there to support it? In the new study, the Harvard researchers suggest that the smoking gun may lie on the outskirts of the solar system.

The Oort cloud is a huge ball of icy objects that surrounds the solar system at an estimated distance of between 2,000 and 100,000 Astronomical Units (AU) from the Sun. For reference, the Earth is 1 AU from the Sun, and even Pluto usually orbits at a distance of only 40 AU.

Exactly how such a cloud of objects formed so far away remains a mystery. Current thinking goes that they’re leftover crumbs from the formation of the solar system’s planets and moons, much like the asteroid belt. But that story has a few holes in it.

Instead, the team’s new hypothesis posits that Oort cloud objects were more likely passersby that were captured by the gravity of two Suns.

“Previous models have had difficulty producing the expected ratio between scattered disk objects and outer Oort cloud objects,” says Amir Siraj, co-author of the study. “The binary capture model offers significant improvement and refinement, which is seemingly obvious in retrospect: most Sun-like stars are born with binary companions.”<<

ABSTRACT from original paper:

We show that an equal-mass, temporary binary companion to the Sun in the solar birth cluster at a separation of ~103 au would have increased the likelihood of forming the observed population of outer Oort Cloud objects and of capturing Planet Nine. In particular, the discovery of a captured origin for Planet Nine would favor our binary model by an order of magnitude relative to a lone stellar history. Our model predicts an overabundance of dwarf planets, discoverable by Legacy Survey of Space and Time, with similar orbits to Planet Nine, which would result from capture by the stellar binary.

The research was published in The Astrophysical Journal Letters.

Source: Harvard-Smithsonian Center for Astrophysics

there doesn’t seem to be any Brown in this paper

dv said:

there doesn’t seem to be any Brown in this paper

He’s probably gone to town

dv said:

there doesn’t seem to be any Brown in this paper

There doesn’t have to be. Still influenced by Brown.

OK. Let’s go back to the very beginning. Where do comets come from?

Well, apart from the few periodic comets that have had previous close encounters with giant planets, they come from infinity in every direction, equally often in every direction. Now that wouldn’t a problem if they approached with a velocity similar to the nearby stars, ie. of order 90 km/s. If so, then the comets would just be left-over material from the formation of the Milky Way and stars within.

But no, more than 99.9% of comets have an asymptotic velocity of 0 km/s at infinity. You see the problem. That means that these >99.9% of aperiodic comets must have formed at the same time as the solar system, because otherwise they wouldn’t have the same speed through the Milky Way as the Sun.

Let’s dispose of the Sun’s long lost twin up front. Such a star would have a velocity different to the Sun, so different that it is currently so far away as to be unidentifiable. If such a star was near the Sun at any time then it would have exerted a gravitational tug on the Oort cloud, tugging it out of position so much that none of the Oort cloud would now be left around the Sun, and instead strewn out between us and the long lost twin. There wouldn’t be any comets. Kapish? So we can rule out a long lost twin star.

Despite that, comets are still a tough nut to explain. A large fraction of our comets leave the solar system entirely. Hundreds of times more comets are ejected from the solar system than enter it from other solar systems. In equilibrium, the number leaving and entering should be the same. And those entering should have speeds of order 90 km/s. That isn’t happening.

The first possible explanation is that there are far more comets around us now than ever before in the history of Earth. That would rely on the Oort cloud having a relatively close outer edge and a star passing through jostling them into orbits approaching the inner solar system just a million or ten million or 100 million years ago. Bad news for this idea. It’s already been disproved. Stars approaching close to the Sun in the past 100 million years have all been tracked, and none got close enough to that massively disturb the Oort Cloud. So scratch that idea.

That leaves only one even possible solution. It’s highly improbable but it has to be right because nothing else fits. That solution is that the Oort Cloud that formed with and at the same time as the Sun has an extremely distant outer boundary, perhaps even as far as a third of the way to Proxima Centauri. Simultaneously, our solar system has to be close to unique, very few other stars known could have an Oort Cloud that big because if they did then we would be pelted by very many comets originating outsi9de the solar system. Thirdly, our solar system amazingly never came close to any other star during the last 3.8 billion years at least, because if it did then the Oort Cloud would all have been scattered. A consequence of this is that the rate that comets rainj down on us now would have had to have been close to constant over the whole of the last 3.8 billion years.

QED.

mollwollfumble said:

dv said:

there doesn’t seem to be any Brown in this paper

There doesn’t have to be. Still influenced by Brown.

OK. Let’s go back to the very beginning. Where do comets come from?

Well, apart from the few periodic comets that have had previous close encounters with giant planets, they come from infinity in every direction, equally often in every direction. Now that wouldn’t a problem if they approached with a velocity similar to the nearby stars, ie. of order 90 km/s. If so, then the comets would just be left-over material from the formation of the Milky Way and stars within.

But no, more than 99.9% of comets have an asymptotic velocity of 0 km/s at infinity. You see the problem. That means that these >99.9% of aperiodic comets must have formed at the same time as the solar system, because otherwise they wouldn’t have the same speed through the Milky Way as the Sun.

Let’s dispose of the Sun’s long lost twin up front. Such a star would have a velocity different to the Sun, so different that it is currently so far away as to be unidentifiable. If such a star was near the Sun at any time then it would have exerted a gravitational tug on the Oort cloud, tugging it out of position so much that none of the Oort cloud would now be left around the Sun, and instead strewn out between us and the long lost twin. There wouldn’t be any comets. Kapish? So we can rule out a long lost twin star.

Despite that, comets are still a tough nut to explain. A large fraction of our comets leave the solar system entirely. Hundreds of times more comets are ejected from the solar system than enter it from other solar systems. In equilibrium, the number leaving and entering should be the same. And those entering should have speeds of order 90 km/s. That isn’t happening.

The first possible explanation is that there are far more comets around us now than ever before in the history of Earth. That would rely on the Oort cloud having a relatively close outer edge and a star passing through jostling them into orbits approaching the inner solar system just a million or ten million or 100 million years ago. Bad news for this idea. It’s already been disproved. Stars approaching close to the Sun in the past 100 million years have all been tracked, and none got close enough to that massively disturb the Oort Cloud. So scratch that idea.

That leaves only one even possible solution. It’s highly improbable but it has to be right because nothing else fits. That solution is that the Oort Cloud that formed with and at the same time as the Sun has an extremely distant outer boundary, perhaps even as far as a third of the way to Proxima Centauri. Simultaneously, our solar system has to be close to unique, very few other stars known could have an Oort Cloud that big because if they did then we would be pelted by very many comets originating outsi9de the solar system. Thirdly, our solar system amazingly never came close to any other star during the last 3.8 billion years at least, because if it did then the Oort Cloud would all have been scattered. A consequence of this is that the rate that comets rainj down on us now would have had to have been close to constant over the whole of the last 3.8 billion years.

QED.

Time and further research will decide the fate of this new theory as it will for past opinions.

>>While the Sun is very clearly a solo act nowadays, some astronomers theorize that it once had a binary companion star. Now, Harvard scientists have added weight to the idea by showing that an ancient binary solar system explains the strange structure of the Oort cloud, and possibly the hypothetical Planet Nine. Best of all, the team outlines how we could check.

The Sun was born about 4.6 billion years ago in a gigantic cloud of dust and gas. But it almost certainly wasn’t alone – if other stellar nurseries are anything to go by, then countless other baby stars would have formed around the same time. Most of them would have drifted away soon after, spreading through the galaxy.

But some scientists believe there’s evidence that the Sun had a twin long after it left the nest. Previous work has shown that many Sun-like stars are born with companions, forming binary pairs. Over a few million years or so, most drift apart to form single-star systems, while others move closer and become tighter-knit binaries. If the Sun was once half of a binary pair, it would obviously belong to the first group.

It’s an interesting story, but what evidence is there to support it? In the new study, the Harvard researchers suggest that the smoking gun may lie on the outskirts of the solar system.<<