Free-floating planets may be born free

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Tiny, round, cold clouds in space have all the right characteristics to form planets with no parent star. New observations, made with Chalmers University of Technology telescopes, show that not all free-floating planets were thrown out of existing planetary systems. They can also be born free.


Previous research has shown that there may be as many as 200 billion free-floating planets in our galaxy, the Milky Way. Until now scientists have believed that such "rogue planets", which don't orbit around a star, must have been ejected from existing .

New observations of tiny dark clouds in space point out another possibility: that some free-floating planets formed on their own.

A team of astronomers from Sweden and Finland used several telescopes to observe the Rosette Nebula, a huge cloud of gas and dust 4600 light years from Earth in the constellation Monoceros (the Unicorn).

Written By: PhysOrg
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  1. Currently planets are divided into rocky, gas giant, ice giant, and dwarf types. I wonder if originating outside of a star’s accretion disc should warrant additional types?

    Someone get Neil deGrasse Tyson on the horn, this kind of thing is his bag.

    • In reply to #1 by Callinectes:

      Currently planets are divided into rocky, gas giant, ice giant, and dwarf types. I wonder if originating outside of a star’s accretion disc should warrant additional types?

      A lot of lighter atoms and molecules have been swept off the rocky planets of the inner Solar System (a continuing process) by the Solar wind and energised by Solar radiation, while planets like Earth accumulate heavy elements from meteors and space dust.

      http://www.abc.net.au/science/articles/2013/06/19/3785100.htm
      The Earth gains about 40,000 tonnes of dust each year. A decent meteor storm can add a tonne in a single go. But the vast majority of this dust is stuff left over from when our solar system was formed. The gravitational field of our Earth just sucks it in.

      What about losses?

      Each year about 95,000 tonnes of hydrogen and 1600 tonnes of helium leave the Earth for outer space. They’re gone forever.

      The lighter materials accumulate in the outer Solar System, so the presence of a star has a considerable effect on the planetary composition at different orbital distances. The very act of orbiting a star, means planets are sweeping material from their orbits.
      There is also the significant issue of planet building collisions, arising from eccentric orbits around the star, as part of the early accretion process.

      There is a variation in the percentage of heavy elements in different galaxies and different parts of galaxies, according to how many supernova events have happened during the history of that locality.

      We should therfore, expect a range differences in free floating planets. (….. and for that matter, different compositions of stars and planets, according to their position in the galaxy.)

      • In reply to #5 by SaganTheCat:

        In reply to #3 by old-toy-boy:

        too small to reflect enough starlight to be seen or to cold to give off enough IR

        That sounds rather like matter that’s, er, dark to me. I guess you mean an alternative to strange theories about why there is “dark matter”. Dark matter isn’t a described thing as such, it’s more of an accounting discrepancy, so maybe it’s best to talk about it being a dark matter than matter that is dark.

  2. this makes sense

    the differnces between a gas giant and a brown dwarf (so called “failed stars”) are somewhat arbitary, gas floats about, clouds can collapse to the point they form accretion discs. if there’s enough mass it’ll start a fusion reaction, if not it wont

    space might be littered with such objects floating about, too small to reflect enough starlight to be seen or to cold to give off enough IR

    would it be too much of a stretch for me to suggest an alternative to “dark matter”?

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