The first interstellar immigrant to our solar system has been spotted: Space rock trapped in Jupiter's orbit is the first known asteroid to have been captured from another star system

  • Rock is the first known asteroid to have been captured from another star system 
  • The object hopped systems while the sun was part of a packed star cluster
  • These star systems were so close together that they frequently shared asteroids 
  • Scientists identified the asteroid after they noticed it had an unusual orbit

  • The first permanent immigrant to our solar system has been spotted by astronomers.
    The space rock is currently trapped in Jupiter's orbit and is the first known asteroid to have been captured from another star system.
    While the cigar-shaped 'Oumuamua was an interstellar interloper that passed through our system last year, the new object, dubbed 2015 BZ509, is here to stay.
    Researchers said the asteroid hopped to the solar system 4.5 billion years ago while the sun was still part of a tightly packed cluster of stars.
    These star systems were so close together that they frequently shared asteroids and other material before later becoming distant neighbours as the universe expanded.


    The first known permanent immigrant to our solar system has been spotted by astronomers. Asteroid 2015 BZ509 (circled in yellow) is currently trapped in Jupiter's orbit and is the first known asteroid to have been captured from another star system

    The researchers, from institutions in France and Brazil, said they identified the intertsellar asteroid after they noticed it had an unusual orbit.
    All eight planets in the solar system, as well as the vast majority of other space objects, travel around the sun in the same direction.
    However 2015 BZ509 is different - it moves in the opposite direction in what is known as a 'retrograde' orbit.

    'How the asteroid came to move in this way while sharing Jupiter's orbit has until now been a mystery,' said study lead author Dr Fathi Namouni, a researcher at the Nice Observatory in France.
    'If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them.'
    The team ran simulations to trace the location of 2015 BZ509 right back to the birth of the solar system 4.5 billion years ago when the era of planet formation ended.

    This is an image of stellar nursery NGC 604 (NASA/HST), where star systems are closely packed and asteroid exchange is thought to be possible. Asteroid 2015 BZ 509 emigrated from its parent star and settled around the sun in a similar environment billions of years ago

    This is an image of stellar nursery NGC 604 (NASA/HST), where star systems are closely packed and asteroid exchange is thought to be possible. Asteroid 2015 BZ 509 emigrated from its parent star and settled around the sun in a similar environment billions of years ago

    The computer models showed that 2015 BZ509 has always moved with this orbit, and so could not have formed alongside the planets in the solar system.
    This means the rocky object must have been captured from elsewhere.
    'Asteroid immigration from other star systems occurs because the sun initially formed in a tightly-packed star cluster, where every star had its own system of planets and asteroids,' said Dr Helena Morais, a researcher at Sao Paulo State University in Brazil and the paper's other author.

    The researchers, from institutions in France and Brazil, said they identified the intertsellar asteroid (circled in yellow) after they spotted its unusual orbit 

    The researchers, from institutions in France and Brazil, said they identified the intertsellar asteroid (circled in yellow) after they spotted its unusual orbit 

    'The close proximity of the stars, aided by the gravitational forces of the planets, help these systems attract, remove and capture asteroids from one another.'
    Scientists said they are unsure which star system the interloper came from, and don't know how far it travelled to reach our own system.
    Dr Namouni told MailOnline this was the 'next step' for the team as they attempt to decipher the origin of BZ509. 
    'We will be simulating the tightly-packed star cluster that the solar system formed in and try and capture asteroids from other systems,' she said.

    WHAT ARE THE DIFFERENT TYPES OF SPACE ROCKS?

    An asteroid is a large chunk of rock left over from collisions or the early solar system. Most are located between Mars and Jupiter in the Main Belt.
    comet is a rock covered in ice, methane and other compounds. Their orbits take them much further out of the solar system.
    meteor is what astronomers call a flash of light in the atmosphere when debris burns up.
    This debris itself is known as a meteoroid. Most are so small they are vapourised in the atmosphere.
    If any of this meteoroid makes it to Earth, it is called a meteorite.
    Meteors, meteoroids and meteorites normally originate from asteroids and comets.
    For example, if Earth passes through the tail of a comet, much of the debris burns up in the atmosphere, forming a meteor shower.

    'If we manage to do that then we will know how long it travelled.'
    The discovery of the first permanent asteroid immigrant in the solar system has important implications for the open problems of planet formation, solar system evolution, and possibly the origin of life itself.
    Understanding exactly when and how 2015 BZ509 settled in the solar system provides clues about the sun's original star nursery.
    It also sheds light on the potential enrichment of our early environment with components necessary for the appearance of life on Earth.

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