2012 VP113
2012 VP113 is a Sedna-like trans-Neptunian object (TNO) and potential dwarf planet candidate in the outer Solar System, distinguished by its extreme orbital isolation and distance from the Sun.[1] Discovered on November 5, 2012, by astronomers Chadwick A. Trujillo and Scott S. Sheppard using the Dark Energy Camera on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile, it was confirmed through follow-up observations at the Magellan and Canada-France-Hawaii telescopes.[1] With an estimated diameter of approximately 450 kilometers—assuming a typical albedo of 15% for such objects—2012 VP113 (provisionally nicknamed "Biden" due to its designation) exhibits a moderately red optical color, characterized by a spectral slope of 13 ± 2% per 100 nanometers, indicative of irradiation-processed ices rich in complex organics.[1] Its surface properties suggest formation in the giant planet region followed by scattering to its current distant orbit.[1] The object's orbit is highly eccentric and detached from planetary influences, never approaching closer than its perihelion distance of 80 astronomical units (AU) from the Sun—far beyond Neptune's orbit at 30 AU—while reaching an aphelion of about 466 AU.[1] As of the most recent ephemeris (epoch October 17, 2024), its semi-major axis measures 273.1 AU, eccentricity 0.705, and inclination 24.0° relative to the ecliptic, yielding an orbital period of approximately 4,514 years.[2] Its absolute magnitude of H = 4.05 places it among the brighter TNOs, though its great distance (as of November 2025, around 84 AU) renders it faint, with an apparent visual magnitude of about 23.4.[2] Unlike scattered-disk objects perturbed by Neptune, 2012 VP113's trajectory lies entirely beyond 45 AU, classifying it as a sednoid and highlighting its dynamical stability in the inner Oort cloud region.[1] The discovery of 2012 VP113 alongside Sedna (perihelion 76 AU) implies a substantial population of inner Oort cloud objects, potentially outnumbering all other known Solar System small-body populations combined, extending from roughly 2,000 to 10,000 AU.[1] This supports the existence of an unseen massive perturber—possibly a super-Earth-mass planet at hundreds of AU—to explain the clustered orbits of such extreme TNOs, a hypothesis further explored in subsequent surveys by the discovery team, including the 2025 discovery of the sednoid 2023 KQ14 ("Ammonite").[1][3] Observations continue to refine its path and search for similar bodies, underscoring 2012 VP113's role in probing the Solar System's formative history and undiscovered architecture.[4]Discovery and Naming
Discovery Circumstances
2012 VP113 was discovered on November 5, 2012, by astronomers Scott S. Sheppard of the Carnegie Institution for Science and Chad A. Trujillo of the Gemini Observatory, during observations at the Cerro Tololo Inter-American Observatory in Chile.[1][5] The detection utilized the Dark Energy Camera (DECam) mounted on the Victor M. Blanco 4 m Telescope, which provided the wide-field imaging capability necessary for spotting faint, slow-moving objects in the distant outer Solar System.[1][6] This discovery formed part of a dedicated survey for trans-Neptunian objects with perihelia exceeding 30 AU, particularly targeting regions beyond 50 AU where such bodies are expected to exhibit minimal motion between exposures.[1] The strategy involved systematic imaging of large sky areas to identify candidates with unusual orbital characteristics, building on prior searches that had revealed Sedna in 2003.[1][7] Precovery identifications extended the known observational history of 2012 VP113, with the object recognized in archival images from as early as September 19, 2007, thereby lengthening the observation arc to over 16 years and refining initial orbital estimates.[8] The object's existence was formally announced on March 26, 2014, through a publication in Nature by Trujillo and Sheppard, which emphasized its highly eccentric orbit with a perihelion of approximately 80 AU.[1]Informal Nickname
The informal nickname "Biden" for 2012 VP113 was coined by its discoverers, astronomers Scott Sheppard and Chad Trujillo, in reference to the "VP" in the object's provisional designation, which evokes "Vice President" and alludes to Joe Biden, who was the U.S. Vice President at the time of the discovery in 2012.[9][10] Since its announcement in 2014, the nickname "Biden" has been used informally in scientific literature, media reports, and popular discussions to refer to the object, providing a memorable shorthand for this distant trans-Neptunian body.[11][12] However, it has not been officially adopted by the International Astronomical Union (IAU), and the object retains its provisional designation of 2012 VP113 without a permanent number or name.[13] This playful naming aligns with a tradition in astronomy of assigning informal monikers to remote Solar System objects, such as the earlier "Sedna" for another distant body that later received official naming, though 2012 VP113's extreme distance and faintness have delayed any formal naming process under IAU guidelines.[9][11]Physical Characteristics
Size and Albedo
The diameter of 2012 VP113 has not been directly measured but is estimated from its absolute magnitude and assumed geometric albedo using the standard relation for trans-Neptunian objects:D = \frac{1329}{\sqrt{p}} \times 10^{-0.2 H}
km, where D is the diameter, p is the geometric albedo, and H is the absolute magnitude in the V-band (assumed equivalent for R-band photometry here).[14] With H \approx 4.1 and a moderate albedo of p = 0.15 typical for trans-Neptunian objects, the estimated diameter is approximately 450 km.[1] This assumption derives from the object's observed reduced magnitude of 3.8 ± 0.04 in the R-band at a heliocentric distance of 83 AU, converted via standard photometric relations.[1] Varying the albedo over a plausible range for such objects (0.04 to 0.4) yields a diameter range of 300–1,000 km, reflecting uncertainties in surface reflectivity.[1] For comparison, this makes 2012 VP113 roughly half the size of Sedna, which has an estimated diameter of 1,000 km under similar albedo assumptions.[1] At the upper end of the size range, 2012 VP113 could approach dwarf planet candidacy, though its current estimate places it below the typical ~600 km threshold for hydrostatic equilibrium in icy bodies.[1] No direct mass measurement exists for 2012 VP113, but assuming a spherical shape and low density similar to other trans-Neptunian objects (~1–2 g/cm³, consistent with icy compositions and measured densities of comparably sized bodies like those in the 300–600 km range), the implied mass would be on the order of $10^{20} kg.[15] To refine the size estimate and potentially resolve its shape or detect moons, imaging with the Hubble Space Telescope has been scheduled under proposal 18010 in Cycle 33 (2026), targeting mid-sized trans-Neptunian objects for high-resolution observations.[16]
Surface Properties
2012 VP113 displays a moderately red coloration in the visible spectrum, characteristic of many trans-Neptunian objects, with measured color indices of B-V = 0.88 ± 0.08 and V-R = 0.55 ± 0.07 based on broadband photometry from multiple epochs.[17] This reddish hue arises from the processing of surface materials by solar and cosmic radiation over billions of years.[1] The object's reflectivity spectrum is featureless across the 0.4–0.9 μm range, exhibiting a linear red spectral slope of 13 ± 2% per 100 nm, which aligns with observations of other detached disk objects.[1] Such a slope indicates an organic-rich surface dominated by irradiated hydrocarbons, likely in the form of tholins—complex, reddish polymers produced from the irradiation of simple ices.[1] Water ice is also inferred as a primary component, contributing to the overall albedo and spectral neutrality in certain bands, while more volatile species like methane are absent, consistent with the object's extreme heliocentric distance preventing their retention.[1] No moons or companions have been detected for 2012 VP113 despite targeted searches in the original discovery images from the Dark Energy Camera and follow-up observations with the Magellan and Subaru telescopes, which would have revealed any significant perturbers within the surveyed fields.[1] The lack of observed orbital perturbations further constrains potential companions to masses below those capable of inducing measurable effects over the observation baseline.[1] Photometric monitoring reveals minimal brightness variations, with a lightcurve amplitude upper limit of less than 0.15 magnitudes derived from multi-night observations, implying a nearly spherical shape with no prominent surface features or elongations.[1] This homogeneity supports the interpretation of a geologically inactive surface shaped primarily by primordial accretion and long-term irradiation.[1]Orbital Parameters
Key Elements
2012 VP113 orbits the Sun on a highly elongated path characterized by a semi-major axis of 273.1 AU (epoch 2024-Oct-17), which represents the average distance from the Sun over the course of its orbit.[18][2] This places the object far beyond the Kuiper Belt, in the inner Oort Cloud region. The semi-major axis is a fundamental parameter derived from observations and used to compute other orbital elements via Keplerian mechanics. The object's perihelion distance, the closest approach to the Sun, is 80.60 AU, marking the farthest known perihelion for any minor planet as of 2025.[18][2] Its aphelion, the farthest point from the Sun, reaches 466 AU. These extreme distances highlight the orbit's vast scale, with 2012 VP113 spending most of its time near aphelion in the distant outer solar system. The eccentricity of 0.705 quantifies this elongation, indicating a highly elliptical trajectory where the object swings dramatically between perihelion and aphelion.[18][2] The orbital period of 2012 VP113 is 4,514 Earth years, determined using Kepler's third law, which states that the square of the orbital period P (in years) is proportional to the cube of the semi-major axis a (in AU): P^2 \propto a^3. For objects orbiting the Sun, the constant of proportionality is 1, so P = \sqrt{a^3}. Substituting a = 273.1 AU yields a^3 \approx 2.037 \times 10^7, and \sqrt{a^3} \approx 4514 years, confirming the lengthy duration of one complete orbit.[18][2] Additional angular elements define the orbit's orientation relative to the ecliptic plane: an inclination of 24.0°, an argument of perihelion of 294.2°, and a longitude of the ascending node of 90.9°.[18][2] The last perihelion passage occurred on October 25, 1979, with the next expected around 6493 AD. The observation arc spans from 2007 to the present, enabling precise ephemerides through the JPL Small-Body Database.[18] This Sedna-like perihelion underscores its extreme detached orbit.Dynamical Evolution
The orbit of 2012 VP113 is dynamically stable against perturbations from Neptune, as its perihelion distance of approximately 80 AU places it well beyond Neptune's orbital radius of 30 AU, preventing close encounters with a minimum separation exceeding 50 AU in the current epoch. This detachment results in minimal mean-motion resonances with Neptune, limiting short-term gravitational influences from the giant planets. Over gigayear timescales, however, the orbit undergoes chaotic evolution driven by overlapping resonances and distant perturbations, though it occupies a narrow stable region in orbital parameter space where eccentricity and inclination remain nearly constant for at least 4.5 Gyr.[19] Evolutionary models propose that 2012 VP113 originated from scattering in the Neptune region during the giant planets' migration, which occurred roughly 4 Gyr ago as part of early Solar System instability scenarios like the Nice model. Alternatively, it may represent a captured interstellar object perturbed into its current orbit by passing stars in the Sun's birth cluster. N-body simulations support these origins, indicating that such objects detached from direct giant planet influence around 4 Gyr ago, with the population of inner Oort cloud bodies like 2012 VP113 forming through these mechanisms rather than ongoing scattering.[20] In the future, 2012 VP113's trajectory within the inner Oort cloud will experience gradual perihelion evolution primarily from galactic tides and occasional stellar perturbations, though its relatively low semi-major axis of approximately 273 AU results in minimal variation compared to more distant objects.[21] N-body integrations using tools like the Mercury integrator demonstrate high long-term survival, with over 98% of orbital clones remaining bound after 1 Gyr and stability extending beyond 5 Gyr for the nominal orbit, implying a survival probability exceeding 90% over the Solar System's remaining lifetime.[3]Classification and Significance
Sednoid Status
Sednoids are a class of trans-Neptunian objects characterized by detached orbits with semi-major axes greater than 150 AU and perihelia greater than 50 AU, ensuring they experience negligible gravitational influence from Neptune.[1] These objects represent the innermost portion of the Oort cloud, distinct from more inner populations like the Kuiper belt or scattered disc. 2012 VP113 qualifies as a sednoid with a perihelion of approximately 81 AU and semi-major axis of 273 AU (as of epoch October 2024), making it the second such object discovered after Sedna in 2003.[2] As of November 2025, only four sednoids are known, highlighting the rarity of this population.[3] The known sednoids share highly eccentric orbits but vary in their exact parameters, as summarized below (current osculating elements, rounded):| Object | Perihelion (AU) | Semi-major axis (AU) |
|---|---|---|
| Sedna (2003 VB12) | 76 | 507 |
| 2012 VP113 | 81 | 273 |
| Leleākūhonua (2015 TG387) | 65 | 1080 |
| 2023 KQ14 | 66 | 252 |