Some of the peculiar aspects of our solar system – comet, dwarf planets in a strange orbit, and, if it really exists, the possible planet's nine far from the sun – are linked to another star's close approach to our system. baby-skipped helter-skelter.
But are star flybys really capable of knocking planets, comets and asteroids, transforming all planetary systems?
UC Berkeley and Stanford University astronomers think they have now found a smoking gun.
The planet, orbiting the new binary star, could have been disturbed by another couple of stars that slid too close to the system from 2 to 3 million years ago, soon after the planet was formed from a shaking dust and gas disk.
If this is confirmed, it reinforces the arguments that dipped stars do not help to soar the systems and can determine if they are planets with stable orbits.
"One of the mysteries created by exoplanet research is that we see systems in which the planets are wrongly arranged, even though they were born on a flat circular disk," said Paul Kalas, auxiliary professor of astronomy. “Perhaps the cosmic tsunami hit these systems and rearranged everything about them, but we have no evidence. Our document provides rare observations on one of these planes that gently influence one of the galaxy planetary systems. ”
Astronomers are already looking for a solar flight in the past, but since then 4.6 billion years ago, most of the evidence has been cold. The star system studied by astronomers, identified only by HD 106906 and located about 300 light-years from Earth's star constellation Crux, is very young, only about 15 million years old.
Kalas and Robert De Rosa, a former UC Berkeley postdoc, who is currently a researcher at Stanford Kavli Institute of Particle Astrophysics and Cosmology, describes his paper conclusions adopted for publication. Astronomy magazine and are now available online.
Kalas, who are studying new, newly created planetary systems to try to understand what happened in the first years of our own solar system, first focused on HD 106906 in 2015, when it was found to have a huge planet in a very unusual orbit. The planet known as HD 106906 b has about 11 Jupiter masses, and its orbit HD 106906 – recently discovered that it is a binary star – in orbit, arched about 21 degrees from the disk plane containing all the other material. star. Its current location is at least 738 times as far from the Earth as the sun, or about 18 times its star than Pluto is out of the sun.
Kalas used both the Gemini Planet Imager on the Gemini Telescope in the Andes of Chile and the Hubble Space Telescope to look closely at HD 106906 and discovered that the star also had a comet belt. The strange orbit of the planet and the fact that the dust disk itself was asymmetrical pointed out that something had disturbed the new system.
Kalas and his colleagues, including De Rosa, suggested that the planet was fired from its solar system by interacting with another, yet unseen planet, or by passing a star. Now, Kalas and De Rosa believe that both have happened: the planet was invaded by an eccentric orbit, when it was dangerous close to the central binary star, a scenario proposed by the theoretician Laetitia Rodet in 2017 and her collaborators from the Grenoble Observatory in France. The recurring gravitational beats from the binary would have quickly planned the planet in an interstellar space, but passing the stars saved the planet by setting its orbit for a safer distance from the binary.
The Gaia Space Observatory provided them with the necessary data to test their hypothesis. Launched in 2012 by the European Space Agency, Gaia collects accurate distance, position, and motion measurements of 1.3 billion stars in the Milky Way Galaxy, 10,000 times larger than Gaia's predecessor, Hipparcos.
Kalas and De Rosa compiled Gaia's information about 461 stars in the same cluster as HD 106906 and calculated their positions back over time – to talk, change the cosmic clock, and discover that another binary star system may be close enough to 3 million years . change planetary system.
"What we have done here is to find stars that could give the HD 106906 b an extra gravitational blow, a second blow to make it last, just like a hypothetical planet Nine would be in our Solar System," Kalass said.
They also found that the binary star came into a trajectory that was about 5 degrees from the system disk, making it even more likely that the interaction had a strong and lasting impact on HD 106906.
Such double beats can be important to stabilize planets, asteroids and comets around the stars.
"Researching the HD 106906 planetary system is like a return to watching the cloud of the Oortian comets that are formed around our new sun," he said. “Our enormous planet's gravitational way has resulted in countless comets flying long distances. Many were squeezed completely, becoming interstellar objects such as Oumuamua, while others were affected by long stars. This star-driven second shot can separate the comet's orbit from any future meeting with the planets, saving it from the perspective of discarding. This chain of events has kept the primitive solar system material deeply freezing far from the sun for billions of years.
Kalas hopes that further observations, such as the updated Gaia measurement catalog, will clarify the meaning of the flight HD 106906.
"We started with 461 suspects and found two who were in the crime scene," he said. "Their exact role will be revealed when we get more evidence."
The work was supported by the National Science Foundation (AST-1518332), the National Aeronautics and Space Administration (NNX15AC89G) and the Nexus Exoplanet System for Science (NExSS), coordinated by the NASA Science Mission Directorate (NNX15AD95G).