A NEW speck found circling at the extreme edge of our solar system has renewed speculation there may yet be a mysterious ‘Planet X’ awaiting discovery.
It’s called Object V774104.
It’s between 500 and 900 kilometres in diameter.
It appears to be a dwarf planet, in the league of Ceres which is currently being surveyed by the Dawn space probe in the asteroid belt between Mars and Jupiter.
And that it shouldn’t be there.
It’s currently sitting some 103 times the distance from the Sun as Earth (Astronomical Units). That’s 15.5 billion kilometres from the Sun.
This makes it the most distant object ever recorded in orbit around the Sun, placing it beyond the Kuiper Belt (where Pluto orbits) and into the Oort Cloud. This where the primordial rubble left over from the formation of the solar system has sat undisturbed for billions of years.
The journal Nature reports Object V774104 was announced to the American Astronomical Society’s Planetary Sciences division earlier this week after its discovery in October.
“How this object got there is a mystery,” Dr Luke Davies of the International Centre for Radio Astronomy Research in WA.
“There are many possible culprits and the detection of these strange icy worlds, leads to a great astronomical who-done-it. Were they flung out by an as yet undetected larger object? Is that larger object even still in our system? Or were they left behind as another star system whizzed by our local neighbourhood - like a forgotten child left at the school gates? More detailed observations over the next couple of years will hopefully tell us the answer.”
LOITERING WITH INTENT
How it got there has astrophysicists scratching their heads.
It joins a series of recently discovered planetoids lurking in the fringes.
Sedna and 2012 VP113 are currently wobbling their way around the Sun at distances of roughly 80AU.
They shouldn’t be there. Nor should Object V774104.
Unless something tossed them out there.
“All that should be out at the edges of our solar system is tiny bits of rubble, leftovers from the messy business of planet formation,” says Swinburne University astrophysicist Dr Alan Duffy.
To explain their presence, somewhere out there would need to be a large, dark world — roughly the size of Neptune. Alternately, a similar effect could be produced by two dark ‘super-Earths’.
But there is simply insufficient data to pin it — or them — down.
All we know for certain is that Neptune and the other inner planets don’t have sufficient gravitational influence to explain their orbits.
And ‘Planet X’ may even no longer be there: The possibility remains it was ejected from orbit billions of years ago, leaving behind a ‘fingerprint’ in the orbits of nearby objects.
There are, however, alternative ideas: Perhaps they were lured away from warmer inner orbits by a wandering star. Or perhaps even ‘jumped ship’ from one. Such wandering stars are believed to have grazed the edge of our Solar System in our deep past.
Some believe just such an incident may be panning out now around the star KIC 8462852. The idea of massive clouds of comets being stirred up by its passage make more sense than a solar-system spanning alien megastructure.
Otherwise, Object V774104’s loopy track may simple be a leftover effect of the primordial game of ping-pong which saw snowballs and clumps of rock merge together to form the Sun and planets.
“I can’t imagine how a world this size can coalesce from the enormously dispersed fragments in this dark and frozen region of our Solar System,” Dr Duffy says. “That’s why we seriously consider that this object formed closer to the Sun but was gravitationally bullied by the other planets and flung out its current location.”
ON THE EDGE
Object V774104 was found along with a dozen other, smaller, objects by astronomers using the Subaru telescope on Mauna Kea in Hawaii. All may be part of the Oort Cloud.
But astronomers don’t yet know much at all about this distant lump of stuff. Not even its orbit.
Too few observations have yet been made to plot its course, or analyse its composition.
Is it like Sedna, which was found in 2003? This planetoid’s unusual orbit is calculated to take it out as far as 937AU. Object 2012 VP113 appears to sling out as far as 452AU.
What would make Object V774104 particularly interesting is if its orbit comes no closer than 50AU where the more ‘mundane’ planetoids live. This would make it a permanent resident of the mysterious Oort cloud.
A lot of eyes are now watching this lonely wanderer to find out.
The next look is scheduled for as early as next week: The Magellan Telescopes in Chile will survey the region of the sky in which it resides. It will then take another set of snapshots in a year’s time — to help calculate its orbit.
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