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Before astronomers pointed their telescopes at the Sun in the early 17th century, the star had already existed for around 4.5 billion years. We have only ever seen a brief glimpse into the long and extended life cycle of our Sun.
According to a new study, we missed a spectacular sight: A long time ago, the Sun varied in brightness and activity. He may also have had a twin.
The study, published this week in Letters from the astrophysical journal, suggests a model that the Sun was part of a binary system. The authors theorize that the Sun’s companion was kicked out by another star that got too close.
The pattern has implications for the mysterious Planet Nine, increasing its chances of having been captured by the stellar duo once.
The idea may sound crazy to most, but Amir Siraj, lead author of the article and student at Harvard University, finds it somewhat unsurprising.
“Much of the Sun-like stars are born with binary companions,” Siraj says Reverse. “And so, in retrospect, it’s quite surprising that it has never been seriously considered that the Sun had a first binary companion that was lost. “
The link between the sun and planet 9
The idea for this study emerged as Siraji searched for answers for the formation of the Oort Cloud and the mystery behind a supposed new planet.
The Oort Cloud is a theoretical cloud of small icy objects that surround the Sun at a distance of up to 3.2 light years. Meanwhile, Planet Nine is a hypothetical ninth giant planet that orbits the Sun in a very elongated orbit that sits well beyond Pluto.
This potential planet, also called “Planet X”, can be about 10 times the mass of Earth and orbit about 20 times farther from the Sun than Neptune, the eighth and furthest known planet from the Sun. However, it has never been observed directly.
“I was interested in two independent problems, the first being the formation of the Oort cloud,” says Siraj.
While there has been extensive modeling of this cloud, none of the models quite match the ratio of objects that exist in the Oort cloud.
“Besides, there is Planet Nine which fascinates me personally”, adds Siraj.
Astronomers from the California Institute for Technology (CALTECH) announced the discovery of Planet Nine in 2015 based on mathematical evidence. Although its existence is still theoretical until today, the direct detection of a ninth planet would be the first discovery of a new planet orbiting the solar system in two centuries.
However, astronomers have not been able to come up with a model to explain how planet nine could have emerged and traveled so far from the Sun in the first place. The three main theories are either:
- He was captured and shot
- It formed in a distant place
- It formed among the giant planets of the solar system, then dispersed
“What surprised me was that all of these training scenarios had low probabilities,” Siraj says. “I had these two kinds of puzzles in the solar system that I had been thinking about for a while.”
Through his research into binary star systems, Siraj knew that these systems were much more efficient at capturing objects than single stars. Based on this, he created a model of the Sun as part of a binary system, with a companion star.
“This greatly increases the likelihood that planet nine exists.”
The stars were said to have been about 1,500 astronomical units apart and circled around their shared center of mass until a passing star somehow splits the binary duo and expels the mate, according to the study.
As a binary system, the two stars would be able to capture the number of objects in the Oort Cloud, as well as a distant ninth planet. Alone, a lonely sun would not be able to do the same.
The model increases the odds that Planet Nine was captured by a factor of 20, the researchers said.
“This is significant because none of the original Planet Nine scenarios have a particularly high probability,” Siraj says. “This greatly increases the likelihood that planet nine exists.”
Siraj and his colleagues will be able to verify their model thanks to observations of planet nine by the next large synoptic telescope at the Rubin Observatory, which is scheduled to launch in 2021.
“It’s a bit poetic that we may have been part of a binary system before, which could have shaped the Oort cloud,” Siraj says.
Abstract: We show that a temporary binary companion of mass equal to the Sun in the solar birth cluster at a separation of ~ 103 au would have increased the probability of forming the observed population of outer Oort cloud objects and capturing planet nine. In particular, the discovery of a captured origin for Planet Nine would favor our binary model by an order of magnitude over a single stellar story. Our model predicts an overabundance of dwarf planets, discoverable by Legacy Survey of Space and Time, with orbits similar to planet nine, which would result from capture by the stellar binary.
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