Kalpana Kalpana (Editor)

V774104

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Discovery site
  
Subaru Telescope

Dimensions
  
500–1000 km

Absolute magnitude (H)
  
~4

Discovery date
  
13 October 2015

Apparent magnitude
  
~24

Observation arc
  
~2 weeks as of last report

V774104 is a trans-Neptunian object (TNO) with a radius roughly half that of Pluto or somewhat smaller. Currently it is approximately 103 AU from the Sun, a distance of 15.4 billion kilometers (9.6 billion miles). As of the discovery announcement in November 2015, it is the most distant observed natural object in the Solar System. No astrometry has been submitted to the Minor Planet Center, so there are no publicly known orbital elements.

Contents

Discovery

V774104 was discovered by a team using the Subaru Telescope, a large reflecting telescope at the summit of Mauna Kea with a primary mirror 8 meters (26 ft) in diameter. The discovery was announced at the November 2015 meeting of the American Astronomical Society’s Division for Planetary Sciences; the discovery team was led by Scott Sheppard and Chad Trujillo.

Orbit

No astrometry has been released publicly so the object does not have a minor planet designation and the uncertainties of the orbital elements are unknown. Being a trans-Neptunian object so far from the Sun with an observation arc of just a few weeks at the time of its discovery announcement, its perihelion and aphelion have not been securely determined.

Possible sednoid

V774104 might be a sednoid, an enigmatic class of objects in the outer Solar System with only two known members. Sednoids have eccentric orbits that must have been perturbed by something, but could not have been perturbed by any presently known body (their entire orbits lie well outside the influence of Neptune). To be a sednoid, V774104 must have a perihelion greater than 50 AU and a semi-major axis greater than 150 AU, which can be determined when its observation arc is around one year. Only 3 objects are known to have perihelia (closest approach to the Sun) greater than 50 AU: 90377 Sedna, 2012 VP113, and 2004 XR190. But 2004 XR190 has a low orbital eccentricity with perihelion at 51 AU. Sedna and 2012 VP113 have both had their perihelion point lifted well beyond the classic Kuiper belt of 30–50 AU. If V774104 is a sednoid or extreme trans-Neptunian object, it may point towards an undiscovered shepherding planet hundreds of astronomical units from the Sun. It is also possible, however, that the lifted perihelion was a result of the crowded confines of the open star cluster in which the Sun formed. Discovery of additional sednoids and analysis of their orbits should eventually permit identification of the process by which their orbits were disturbed.

Most distant Solar System object

Many news sources heralded V774104 as "the most distant Solar System object". In fact, various long-period and hyperbolic comets are more distant, though all of these are much smaller bodies and not observable at such distances. Since the time of its discovery, the Voyager and Pioneer 10 spacecraft have also been more distant; the Voyager probes are observable via their artificial radio transmissions.

Observed Solar System objects that periodically become more distant than 103 AU from the Sun include Sedna (which is similar or modestly larger in size), 2000 CR105, 2012 DR30, 2013 BL76, and 2005 VX3. There are 595 known objects that have aphelia more than 103 AU from the Sun. This distance is about double the outer limit of the torus-shaped Kuiper belt that lies outside Neptune's orbit. Far beyond this region is the vast spherical Oort cloud enshrouding the Solar System, whose presence was deduced from the orbits of long-period comets.

Study of the population of Solar System objects that are significantly more distant than V774104 will likely require new instruments. The proposed Whipple spacecraft mission is designed to determine the outer limit of the Kuiper belt and directly detect Oort cloud objects out to 10,000 AU. Such objects are too small to detect with current telescopes except during stellar occultations. The proposal involves use of a wide field of view and rapid recording cadence to allow detection of many such events.

References

V774104 Wikipedia