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article imageFirst planet originating from outside the Milky Way discovered

By Kev Hedges     Nov 19, 2010 in Science
Astronomers using a telescope in Chile have discovered the first planet that originated from outside our galaxy, the Milky Way.
Scientists say the Jupiter-like planet is part of a solar system which once belonged to a dwarf galaxy. If this claim is true, the "exoplanet" would be the first ever world discovered within our Milky Way that could be labelled an "immigrant". The find contravenes the leading hypothesis of how and where planets form. The planet exists 2,200 light years away in the Helmi stream, a ring of ancient stars that cuts through the plane of the Milky Way, says Science Now.
The discovery came about because one star in particular caught the scientist's eyes: HIP 13044. This star is nearing the end of its life, and astronomer Johny Setiawan of the Max Planck Institute for Astronomy in Heidelberg, Germany, noticed that the star did not move at a constant velocity relative to our sun. Their instruments detected a 16-day cycle where sometimes the star was closer and at times farther away. This could be stellar pulsations or star spots - but their instruments detected neither leaving only one possibility: a planet gravitationally pulling on the star.
The BBC Science and Environment news reports that this find is the first real "hard evidence", as Dr Robert Massey of the UK's Royal Astronomical Society explained:
There's every reason to believe that planets are really quite widespread throughout the Universe, not just in our own galaxy, the Milky Way, but also in the thousands of millions of others there are but this is the first time we've got hard evidence of that.
Another unusual thing about this planet is - it should never have formed in the first place. That's because HIP 13044 is a very ancient, very metal-poor star. It's about 3-billion-years older than our own sun and has only 1% as much metal. The "metals" referred to here are any chemical elements heavier than hydrogen and helium. These basic metals attract other matter and form planets. However, this planet find has violated this hypothesis.
Astronomers meanwhile are not sure if the finding of a planet formed outside the Milky Way or the formation of a planet from a metallic-poor star is the bigger discovery.
More about Planet, Exoplanet, Discovery, Milky way
 
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