Astronomers here in Belfast have just announced that they have discovered what they believe to be the youngest ever planet observed. So young that it may have not completely formed yet. They used radio telescopes in the UK (the MERLIN network) and in the US (the VLA) to study the star system of HL Tau, a star in Taurus about 520 light years from Earth

They were looking at the system’s large and unusually bright proto-planetary disc. What they found initially was that the disc contained fairly large lumps of dust and some rocky sized objects, roughly the size of pebbles. On closer inspection the team also noticed a much larger clumping of dust and gas with a mass of about 14 Jupiter masses; orbiting at the same distance from HL Tau as Neptune does from our Sun.

A few years ago another team of astronomers reported seeing nebulosity in the same region that this proto-planet has been seen; leading these astronomers to conclude that what they are seeing really is a newly forming planet still nestled in the dusty disc out of which it emerged. The young planet (now dubbed HL Tau b) could have potentially formed very recently, meaning that even at its oldest possible age (a 100,000 years) it would still be just one percent as old as the previous youngest planet found.

In the RAS press release Dr Jane Greaves who has just presented a talk here on the exoplanet remarks, “we see a distinct orbiting ball of gas and dust, which is exactly how a very young proto-planet should look.” What’s perhaps even more interesting is the result of a computer simulation run to see how a planet forming disc like this might evolve. What it shows is a planet forming that is very similar to the observed HL Tau b.

This is incredible news and a discovery which is yet another step in tying together the evolution of planetary systems from a dusty proto-planetary disc full of dust and gas to a proper system of planets like our own Solar System. Greaves believes that the planet will eventually form a massive gas giant planet like “a massive version of Jupiter”.

Top image: The real data showing the disc around HL Tau with HL Tau b marked ‘b’
Credit: VLA + Pie Town antenna

Bottom image: A computer simulation showing how a dusty disc like HL Tau’s might evolve.
Credit: Greaves, Richards, Rice & Muxlow 2008