V774104: Could a Dark World Put a New Light on Solar System History?

Newly discovered small Solar System body V774104 may seem just another tiny, cold and remote world beyond Neptune but this is an important finding as its mere existence suggests that the wastes of the outer Solar System are considerably more populous than we thought a couple of decades ago.

 

Until V774104 was discovered Eris (illustrated in this artist's impression) was the most distance observed member of the Solar System. (Image Credit: NASA/JPL-Caltech)

Until V774104 was discovered Eris (illustrated in this artist’s impression) was the most distant observed member of the Solar System. (Image Credit: NASA/JPL-Caltech)

 

Currently about 103 au (about 15 billion km or 9.6 billion miles) from the Sun V774104 is the most distant known trans-Neptunian object (TNO), and probably also a dwarf planet (but, like several other TNOs, we do not yet have enough information to decide this). V774104 hardly rolls off the tongue, but this is just a provisional designation and this little world will probably receive a name eventually.

Far, far beyond Pluto (which is currently about 33 au from the Sun) and more distant even than Eris (about 97 au from the Sun at the time of writing), V774104 almost certainly has a rocky core overlaid by an icy surface dimly lit by the faint rays of the far off Sun. It must be a landscape like that of Niflheim, the primordial world of ice from Norse mythology. This bleak little world was found by astronomers led by Scott Sheppard and Chad Trujillo using the 8m Subaru telescope in Hawaii and the Dark Energy Survey Camera in Chile. They announced their discovery at the 47th meeting of the American Astronomical Society’s Division for Planetary Sciences in Maryland, USA. Based on measurements of the amount of sunlight it reflects back to us, V774104 seems to be 500-1000 km (310-620 km) in diameter, implying that is smaller than Pluto.

So distant an object will have a long orbital period, lasting millenia. Since V774104 has (at the time of writing) not even been observed for a full year, its orbital characteristics are not accurately known yet. Values for its closest and furthest distances from the Sun (its perihelion and aphelion) have still to be established. Its perihelion and aphelion values will be used to decide if V774104 is also a sednoid. What does this mean?

Named after 90377 Sedna, sednoids are trans-Neptunian objects with a perihelion greater than 50 AU and whose orbit has a semi-major axis greater than 150 AU. This means at their closest to the Sun they are still beyond the Kuiper Belt which lies 30-50 au from the Sun. Only two other objects in this category are known: 90377 Sedna and 2012 VP113. They intrigue astronomers as they inhabit what was expected to be a largely empty region between the Kuiper Belt and the Öpik-Oort Cloud, the Solar System’s yet to be observed reservoir of comets. As well, the current highly elliptical orbits of Sednoids cannot be their original orbits, the chance of smaller bodies in such eccentric paths accreting into objects hundreds of kilometres across is fantastically low. Sednoids must have originally formed in relatively circular orbits, possibly in the Oort Cloud. As a result of these unusual features, suggesting a link with the Oort Cloud,  sednoids are also known as Inner Oort Cloud Objects.

The list of sednoids may be set to suddenly expand: the team which discovered V774104 believe that they have found about a dozen other objects around 80 to 90 au from the Sun. It will take at least a year of further observations to understand the orbits of these new discoveries.

The existence of this growing class of iceballs beyond the Kuiper Belt is puzzling as their distant and eccentric orbits cannot be explained by the influences of known Solar System objects. They are too far away from the Sun to be effected by the gravitational tugs of the giant planets yet they are too close to the Sun to be influenced by passing stars. It seems something else has perturbed their original circular orbits to their current elongated forms. That something else could be an undiscovered giant planet comparable to Uranus or Neptune that still orbits far from the Sun (like Percival Lowell‘s mythical Planet X) or even a lost giant planet that was ejected from the Solar System, disrupting the orbits of Oort Cloud objects as it escaped to forever wander interstellar space. Alternatively, rather than a planet being responsible, perhaps it was the infant Sun’s siblings that nudged the sednoids into place. Back when the forming Sun was just one protosun in a stellar nursery, the gravitational influences of other gestating star systems could have disturbed the Oort Cloud enough to dislodge these bodies into their current orbits. Improving our knowledge of the orbits of V774104 and its companions will help provide evidence to select which of these scenarios is most likely.

V774104 and similar tiny and remote ice worlds may have much to teach us about the true extent and history of the whole Solar System.

Further Reading

Astronomers spot most distant object in the solar system, could point to other rogue planets

New Dwarf Planet is Most Distant Object Yet Observed in our Solar System

 

Please note:

  • V774104 cannot in any way effect our planet gravitationally- it is too tiny and far away.
  • Even though the orbit of V774104 is not accurately known yet, it is certain that it has never and will never come close to the inner Solar System planets including Earth.
  • It is not linked to any mythological or real disaster.
  • It is not and was not known as “Nibiru”
  • It was not known to, observed or recorded by the Sumerians, Mayans or any other ancient or historical near Eastern or Meso-American civilisation.

(Article by Colin Johnston, Science Education Director)