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Artist's impression of (225088) 2007 OR10
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Discovery[1]
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| Discovered by | M. E. Schwamb M. E. Brown D. L. Rabinowitz Palomar Observatory (675) |
| Discovery date | 2007-07-17 announced: 2009-01-07 |
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Designations
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| MPC designation | (225088) 2007 OR10 |
| Minor planet category |
SDO[2] 10:3 resonance (DES)[3] |
| Epoch February 8, 2011 | |
| Aphelion | 100.79 AU (Q) 15.1 Tm |
| Perihelion | 33.62 AU (q) 5.03 Tm |
| Semi-major axis | 67.21 AU (a) 10.054 Tm |
| Eccentricity | 0.500 |
| Orbital period | 550.98 yr |
| Mean anomaly | 101.0° (M) |
| Inclination | 30.70° |
| Longitude of ascending node | 336.86° |
| Argument of perihelion | 207.18° |
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Physical characteristics
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| Dimensions | 1200+300 −200 km[5] (fit to volatile-retention model) 875[6]–1400[7] km[4][8] |
| Albedo | ≈ that of Quaoar, 0.18 (assumed from spectrum)[5] |
| Spectral type | red[5] |
| Apparent magnitude | 21.3[9] |
| Absolute magnitude (H) | 2.0[4] |
(225088) 2007 OR10 is a trans-Neptunian object with an absolute magnitude of 2.0.[4] It has been estimated to be between Sedna and Quaoar in size, and is the largest body in the Solar System without a name.[10] Michael Brown thinks it must be a dwarf planet,[11] although the IAU has not yet formally designated it as such, and the mass of the object is unknown.
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2007 OR10 was discovered by California Institute of Technology astronomers as part of the PhD thesis of Meg Schwamb, who was at the time a graduate student of Michael E. Brown.[12] Brown nicknamed the object "Snow White" for its presumed white color,[12] as it would have to be very large or very bright to be detected by their survey.[10] However, it turned out to be one of the reddest objects in the Kuiper belt, comparable only to Quaoar, so the nickname turned out to not be very appropriate. It was however also the "seventh dwarf" discovered by Brown's team, after Quaoar in 2002, Sedna in 2003, Haumea and Orcus in 2004, and Makemake and Eris in 2005.
2007 OR10 is currently the largest known object in the Solar System without an official name. In 2011 Brown decided he finally had enough information to justify giving it one,[5] since the discovery of water ice and the possibility of methane makes it noteworthy enough to warrant study.[12]
2007 OR10 came to perihelion around 1856.[4] It is currently 86 AU from the Sun.[9][13] This makes it the 3rd farthest known large body in the Solar System, after Eris (97 AU) and Sedna (88 AU).[10] It will be further from the Sun than Sedna in 2013.[13] 2007 OR10 will be further than both Sedna and Eris by 2045,[14] and it will come to aphelion (furthest distance from the Sun) in 2130.[13]
The size of an object depends on its absolute magnitude (H) and the albedo (the amount of light it reflects). 2007 OR10 has an absolute magnitude (H) of 2.0 [4] This makes it the fifth brightest TNO known, a little less bright than Sedna (H=1.6; <1600 km)[15] and brighter than Orcus (H=2.3; ~950 km).[16] It is likely that 2007 OR10 has a size somewhere between Sedna and Quaoar (H=2.6).[10]
2007 OR10 is among one of the reddest objects known.[5] This is probably in part due to methane frosts, which turn red when bombarded by sunlight and cosmic rays.[5]
2007 OR10's spectrum shows signatures for both water ice and methane, which makes it similar in composition to Quaoar. The presence of red methane frost on the surfaces of both 2007 OR10 and Quaoar implies the existence of a tenuous methane atmosphere on both objects, slowly evaporating into space. Although 2007 OR10 comes closer to the Sun than Quaoar, and is thus warm enough that a methane atmosphere should evaporate, its larger mass makes retention of an atmosphere just possible.[5] The presence of water ice on the surface of 2007 OR10 implies a brief period of cryovolcanism in its distant past.[17]
2007 OR10 is on an orbit similar to that of the dwarf planet Eris,[18] making it a scattered disc object.[2] 2007 OR10 was discovered when searching for objects in the region of Sedna.[19]
2007 OR10 has been observed 46 times over seven oppositions with precovery images back to 1985.[4]
It was formally announced on January 7, 2009.[1]
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The orbit of 2007 OR10 compared to the orbit of Eris and Pluto. |
The preliminary motion of OR10 librating in a 10:3 resonance with Neptune. This resonance is not confirmed and may be merely a near resonance.[3] |
The Deep Ecliptic Survey (DES) shows the nominal orbit as in a 10:3 resonance with Neptune.[3]
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