Richest ever exoplanet system discovered

Sorry to keep banging on about all this space lark, but when your caught in the middle of a swirling infinity of the stuff, it’s sort of hard to ignore. The latest beat on the cosmos is that a team of Astronomers have discovered a planetary system consisting of at least five planets that orbit a star which is bit of a doppelgänger of our own Sun.

Said star, HD 10180 (suggestions for a decent name in the comments please) is 127 light years away, in the southern constellation of Hydrus. The researchers used the much in demand European Southern Observatory (Eso), to analyze light emitted from the system. Over time they used the data they found to slowly identify and characterize the planets.

It might seem like it’s hard to get too thrilled about something that’s 127 light years away, (also known as sillydistance), but this really is a pretty startling find as it’s easily the richest system of exoplanets – planets outside our own Solar System – ever found. Christophe Lovis from Geneva University’s observatory in Switzerland lead the research team. He claims that his troupe of space brains have probably found “the system with the most planets yet discovered”. Speaking to the BBC, Lovis commented:

“This also highlights the fact that we are now entering a new era in exoplanet research – the study of complex planetary systems and not just of individual planets,”

So about that rather vague sounding process of measuring the light. Lovis’s team used the Eso’s High Accuracy Radial velocity Planet Searcher (or Harps) instrument, which can measure the wobble of a star or more accurately, how much it is being pulled on by an orbiting planet.

“If there is one planet it will induce a little movement – the star will come towards us and move away. And what works for one [planet] works for many.”

With several planets orbiting the star, its movement becomes a very complex “superposition”, which is a scientific way of saying, a rabble of competing planet-induced movements. Gradually isolating and breaking down these various gravitational forces, Lovis’s team calculated how many planets were in the system, the mass of each planet, and even the path of each individual planet’s orbit. Dr Lovis said:

“Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system.”

The astronomers have picked up clear signals from five of the seven planets with the last two giving off slightly “fuzzier” signals. One of these two is estimated to be just 1.4 times the mass of the Earth, potentially making it the least massive exoplanet ever discovered. Weighing in on the find, Martin Dominik, an astronomer and exoplanet hunter from the UK’s University of St Andrews, said the complexity and structure of the HD 10180 system make it a noteworthy discovery.

“The richness of the system of planets around HD 10180 with its many characteristic features marks the way forward towards gathering the information that will put our own existence into cosmic context,”

He was less keen however, to describe this as the “richest system” of exoplanets ever found, stating that already discovered systems may still yield extremely rich, as yet undiscovered, planets. Dr Dominik added:

“I am tempted to consider the detected system as one of the most ‘informative’ ones. Like most discoveries in science, the findings come with more questions than answers; but in my opinion, this is what really advances a field.”

At 127 light years plus, distant from the nearest service station, the HD 10180 system probably isn’t going to become a likely candidate for space tourism or student exchange programs any time soon. Keep watching the skies folks, at the expense of making the understatement of an eon, there really is loads of stuff up there.

Source: BBC News

Post author – Fraser MacInnes