# (225088) 2007 OR10

(Redirected from S/2010 (225088) 1)
Discovery [1][2] 2007 OR10 and its moon seen by the Hubble Space Telescope in 2010 M. E. SchwambM. E. BrownD. L. Rabinowitz Palomar Obs. 17 July 2007 [a] (225088) 2007 OR10 2007 OR10 · p-DP [7] Epoch 27 April 2019 (JD 2458600.5) Uncertainty parameter 4 30.09 yr (10,989 days) 19 August 1985 101.259 AU 33.494 AU 67.376 AU 0.503 553.05 yr (202,003 days) 105.265° 0° 0m 6.415s / day 30.739° 336.844° 207.546° 1[8] 1230±50 km[9] 0.03 (for a rotation period of 22.4 h)[9]0.007 (for a rotation period of 44.81 h)[9] (1.75±0.07)×1021 kg[9] 1.74±0.16 g/cm3[9] ≈ 0.3 ≈ 0.61 22.40±0.18 h or 44.81±0.37 h(ambiguous,[10][11] but 22.4 h more likely[9]) 0.14±0.01[9] B−V=1.38[12]V−R=0.86[13]V−I=1.65±0.03[9] 21.52[14] 2.34[10] · 1.8[1][3] · 2.0[7]

(225088) 2007 OR10, unofficially known as Gonggong, is a possible dwarf planet[15] orbiting the Sun beyond Neptune. It is a member of the scattered disc, a high-eccentricity population of trans-Neptunian objects (TNOs). It was discovered in July 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory. The discovery was announced in January 2009.

At 1,230 km (760 mi) in diameter, (225088) 2007 OR10 is the fifth-largest known body in the Solar System beyond the orbit of Neptune and is expected to have a gravitationally rounded shape, thereby qualifying for dwarf planet status.[7]

It is currently the largest known body in the Solar System without an official name. In 2019, the discoverers hosted an online poll for the general public to choose among three suggested names. Gonggong was announced as the winner. The discovery team plans to submit the name to the International Astronomical Union.

2007 OR10 is red in color, due to the presence of organic compounds called tholins on its surface. It may support a tenuous methane atmosphere that is slowly escaping into space.[16] Water ice is also present on its surface, which hints at a brief period of cryovolcanic activity in the distant past.[17] 2007 OR10 has one known natural satellite, S/2010 (225088) 1.

## History

### Discovery

(225088) 2007 OR10 was discovered by American astronomers Megan Schwamb, Michael Brown and David Rabinowitz on 17 July 2007.[1] The discovery was part of the Palomar Distant Solar System Survey, a survey conducted to find distant objects in the region of Sedna, beyond 50 astronomical units (AU) from the Sun, using the Samuel Oschin telescope at Palomar Observatory near San Diego, California.[18][19][20] The survey was designed to detect the movements of objects out to at least 1,000 astronomical units from the Sun.[20] Schwamb identified 2007 OR10 by comparing multiple images using the blinking technique.[19] In the discovery images, 2007 OR10 appeared to move slowly, suggesting that it is a distant object.[19][21] The discovery was part of Schwamb's doctoral thesis. At that time, Schwamb was a graduate student of Michael Brown at Caltech.[22][19]

2007 OR10 was formally announced in a Minor Planet Electronic Circular on 7 January 2009.[2] Upon its announcement, the object was given the provisional designation 2007 OR10, which indicates its year of discovery, with the letters further specifying that the discovery took place in the second half of July.[2][23] It has been observed 230 times over 13 oppositions and has been identified in two precovery images, with the earliest image taken by the European Southern Observatory on 19 August 1985.[3][24]

### Naming

2007 OR10 is currently the largest known object in the Solar System without an official name.[25] Initially after the discovery of 2007 OR10, Brown nicknamed the object "Snow White" for its presumed white color, because it would have to be very large or very bright to be detected by their survey.[26][17] By that time, Brown's team had already discovered seven large trans-Neptunian objects which were collectively referred to as the "seven dwarfs":[26][17] Quaoar in 2002, Sedna in 2003, Haumea, Salacia and Orcus in 2004, and Makemake and Eris in 2005. However, 2007 OR10 turned out to be very red in color, comparable to Quaoar, so the nickname was dropped.[26][21] On 2 November 2009, two years after its discovery, the Minor Planet Center assigned the minor planet number 225088 to 2007 OR10.[24]

The discoverers were given a 10-year period for naming proposals following the numbering of the object.[27][28] 2007 OR10 was assigned its minor planet number in November 2009, hence the discoverers were given the privilege to propose a name until November 2019.[27][28] Upon the discovery and announcement of 2007 OR10, Brown did not consider naming it as he regarded it to be an unremarkable object despite its large size.[17][29] In 2011, Brown declared that he now had enough information to justify giving it a name, in consideration of the discovery of water ice and the possibility of methane on its surface, which made it noteworthy enough to warrant further study.[22] In 2016, in response to the larger size revisions of 2007 OR10 made in that same year, Schwamb remarked:

In 2019, the discoverers of 2007 OR10 hosted an online poll for the general public to choose between three possible names they thought appropriate: Gonggong (Chinese), Holle (German), and Vili (Norse). These names were selected by the discoverers in accordance to the International Astronomical Union's (IAU's) minor planet naming criteria, which state that objects with orbits like that of 2007 OR10 must be given names related to mythological figures that are associated with creation.[27][28] The three options were also picked because they are associated with water, ice, snow, and the color red, which are all characteristics of 2007 OR10.[30] The voting session ended on 10 May 2019, with Gonggong being the most voted name.[27][19] The satellite of 2007 OR10 will not be named by the hosts of the naming poll as the naming privilege for the satellite of 2007 OR10 is reserved to the discoverers of the satellite.[27][31]

On 29 May 2019, the discovery team announced Gonggong as the winning name, with a plurality of 46 percent of the 280,000 votes casted during the voting session.[31] The discovery team will propose the winning name to the IAU's Committee of Small Body Nomenclature, the institution that is responsible for naming minor planets.[31] The name is derived from Gonggong, a Chinese water god depicted as having a red-haired human head and the body of a serpent. In Chinese mythology, Gonggong was responsible for creating chaos, causing flooding, and tilting the Earth, and was sent into exile.[27][31]

## Physical characteristics

### Surface and spectra

Artist's impression of 2007 OR10 depicting its red surface color.
Colors of trans-Neptunian objects. 2007 OR10's color (not shown) is similar to that of Quaoar.

The surface of 2007 OR10 is red in color. It has an albedo (reflectivity) of 0.14±0.01.[9] The surface composition and spectrum of 2007 OR10 is expected to be similar to that of Quaoar, as both objects are red and display signs of water ice and possibly methane in their spectra.[32][33] The spectrum of 2007 OR10 was first measured in 2011, at near-infrared wavelengths using the Folded port InfraRed Echellette (FIRE) spectrograph on the Magellan Baade Telescope at the Las Campanas Observatory in Chile.[16] The observed spectrum of 2007 OR10 exhibits a strong red spectral slope along with broad absorption bands at wavelengths of 1.5 μm and 2 μm. Additional photometric measurements from the Hubble Space Telescope's Wide Field Camera 3 instrument display similar water ice absorption bands at 1.5 μm.[16] These absorption bands are characteristic features of water ice, which is often found on large Kuiper belt objects.[34] The presence of water ice on the surface of 2007 OR10 implies a brief period of cryovolcanism in the distant past when water erupted from its interior, deposited onto its surface, and subsequently froze.[35]

The red color of 2007 OR10 is unexpected for an object with a substantial amount of water ice on its surface.[35][22] Objects with surfaces rich in water ice are typically neutral in color, hence 2007 OR10 was initially nicknamed "Snow White" for its presumed bright and reflective surface.[26][17] 2007 OR10 is among the reddest objects known.[16] Its red color implies that methane is present on its surface, although it was not directly detected in the spectrum of 2007 OR10 due to the low signal-to-noise ratio of the data.[16] The red color results from methane frost that are irradiated by sunlight and cosmic rays.[16] The photolysis of methane on its surface produces reddish organic compounds known as tholins.[16][10]

2007 OR10 is large enough to be able to retain trace amounts of volatile methane on its surface, even when at its closest distance to the Sun (33.5 AU)[3] where temperatures are higher than that of Quaoar.[16] In particular, the large size of 2007 OR10 means that it is likely to retain other volatiles including ammonia, carbon monoxide, and possibly nitrogen, which almost all trans-Neptunian objects lose over the course of their existence.[32][10][25] Like Quaoar, 2007 OR10 is expected to be near the mass limit at which it is able to retain those volatile materials on its surface.[32][22]

#### Brightness

The size of an object can be calculated from its absolute magnitude (brightness) and albedo.[36] 2007 OR10 has an absolute magnitude (H) of 2.34,[12][10] which makes it the seventh-brightest trans-Neptunian object known. Other sources give an absolute magnitude of 1.8,[3] which would make it the fifth brightest trans-Neptunian object,[37] brighter than Sedna (H=1.83; D=995 km)[38] and Orcus (H=2.31; D=917 km).[39]

Due to its large distance of 88 astronomical units from the Sun, the apparent magnitude of 2007 OR10 is only 21.5, too dim to be seen from Earth with the naked eye.[27][b] It is dimmer than Sedna, which has an apparent magnitude of 20.9.[41]

### Atmosphere

The presence of tholins on the surface of 2007 OR10 implies the existence of a tenuous methane atmosphere slowly escaping into space, analogous to Quaoar.[35][22] Although 2007 OR10 occasionally 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.[16][42] Its low surface albedo may contribute to the loss of volatiles such as nitrogen, since a lower albedo corresponds to more light being absorbed by the surface rather than being reflected, thus resulting in greater surface heating.[42] 2007 OR10 is thought to have had cryovolcanic activity along with a more substantial atmosphere shortly after its formation.[35][22] Such cryovolcanic activity is expected to have been brief, and the resulting atmosphere gradually escaped over time.[35][22] Volatile gases, such as nitrogen and carbon monoxide, were lost, while less volatile gases such as methane are likely to remain in its present tenuous atmosphere.[35][42]

### Size

Size estimates
Year Diameter Method Refs
2010 1,752 km thermal [43]
2011 1,200+300
−200
km
best fit albedo [16]
2012 1,280±210 km thermal [33]
2013 1,142+647
−467
km
thermal [44]
2016 1,834.53 km light curve [13]
2016 1,535+75
−225
km
thermal [10]
Artistic comparison of Pluto, Eris, Haumea, Makemake, 2007 OR10, Quaoar, Sedna, 2002 MS4, Orcus, Salacia, and Earth along with the Moon.
2007 OR10 compared to the Earth and the Moon.

As of 2019, 2007 OR10 is estimated to have a diameter of 1,230 km (760 mi), derived from radiometric measurements, its calculated mass, and assuming a density similar to other similar bodies.[9] This would make 2007 OR10 the fifth-largest trans-Neptunian object, after Pluto, Eris, Haumea, and Makemake.[9] 2007 OR10 is probably larger than both Pluto's moon Charon and the large Kuiper belt object Quaoar, which have diameters of 1,212 km (753 mi) and 1,110 km (690 mi), respectively.[45][46]

Due to its large size, it is very likely a dwarf planet.[7] The International Astronomical Union has not addressed the possibility of accepting additional dwarf planets since before the announcement of the discovery of 2007 OR10. Brown states that 2007 OR10 "must be a dwarf planet even if predominantly rocky", as his 2013 radiometric measurement of 1,290 km (800 mi) is large enough to certainly qualify as a dwarf planet.[7] Scott Sheppard and his colleagues think that it is "likely" to be a dwarf planet,[47] based on its minimum possible diameter (580 km under the assumption of an albedo of 1)[c] and the expected lower size limit of around 200 km (120 mi) for hydrostatic equilibrium in cold icy-rocky bodies.[47]

In 2010, Tancredi initially estimated 2007 OR10 to have a very large diameter of 1,752 km (1,089 mi), though its dwarf planet status was unclear as there was no lightcurve data and other information to ascertain its size.[43] 2007 OR10 is too distant to be resolved directly; Brown placed a rough estimate of its diameter ranging from 1,000 km (620 mi) to 1,500 km (930 mi), based on an albedo of 0.18 that is the best fit in his model.[16] A survey led by a team of astronomers using the European Space Agency's Herschel Space Observatory in 2012 determined its diameter to be 1,280 km (800 mi) with an uncertainty of 210 km (130 mi), based on the thermal properties of 2007 OR10 observed in the far infrared range.[33] This measurement is consistent with Brown's estimate of 1,000–1,500 km (620–930 mi). Later observations in 2013 using combined thermal emission data from Herschel and the Spitzer Space Telescope provided a smaller size estimate of 1,142 km (710 mi), though this estimate had a larger range of uncertainty.[44]

In 2016, combined observations from the Kepler spacecraft and archival thermal emission data from Herschel suggested that 2007 OR10 was much larger than previously thought, giving a size estimate of 1535+75
−225
km
based on an assumed equator-on view and a lower estimated albedo of 0.089.[10][11] This would have made 2007 OR10 the third-largest trans-Neptunian object after Eris and Pluto, larger than Makemake (1430 km).[11][25][48] These observations of 2007 OR10 were part of the Kepler spacecraft's K2 mission which includes studying small Solar System bodies.[25] Subsequent measurements in 2018 revised the size of 2007 OR10 to 1,230 km (760 mi), based on the mass and density of 2007 OR10 derived from the orbit of its satellite and the discovery that the viewing direction was almost pole-on.[9] With this more recent size estimate, 2007 OR10 is again thought to be the fifth-largest trans-Neptunian object.[9]

### Mass, density and rotation

2007 OR10 moving among background stars during a 19-day observation period by the Kepler spacecraft.[25]

Based on the orbit of its satellite, the mass of 2007 OR10 has been calculated to be 1.75×1021 kg, with a density of 1.72±0.16 g/cm3.[9] From these mass and density estimates, the size of 2007 OR10 was calculated to be about 1,230 km (760 mi), smaller than the previous 2016 size estimate of 1,535 km (954 mi).[9] Given the mass of 1.75×1021 kg, the 2016 size estimate of 1,535 km (954 mi) would have implied an unexpectedly low (and likely erroneous) density of 0.92+0.46
−0.12
g/cm3
.[9]

2007 OR10 is the fifth most massive trans-Neptunian object, after Eris, Pluto, Haumea, and Makemake.[9] It is slightly more massive and denser than Charon, which has a mass of 1.586×1021 kg and a density of 1.702 g/cm3.[9][45] Due to its large size, mass, and density, 2007 OR10 is expected to be in hydrostatic equilibrium.[9][10] Its shape is described as a MacLaurin spheroid, being slightly flattened due to its rotation.[9][10]

The rotation period of 2007 OR10 was first measured in March 2016, by observing variations in its brightness using the Kepler space telescope.[10][27] The Kepler observations provided two possible values of 44.81±0.37 and 22.4±0.18 hours for the rotation period.[10] The value of 22.4±0.18 hours is thought to be the more plausible one.[9] 2007 OR10 rotates slowly compared to other trans-Neptunian objects, which usually have rotation periods between 6 and 12 hours.[9] Due to its slow rotation, it is expected to have a low oblateness of 0.03 or 0.007, for rotation periods of 22.4 or 44.81 hours, respectively.[9] The slow rotation period led astronomers to speculate that the rotation of 2007 OR10 was slowed down by tidal forces exerted by an orbiting satellite, which was confirmed later that same year.[49][8][50]

## Orbit

Polar view of the orbits of 2007 OR10, Eris, and Pluto.
Ecliptic view of the highly inclined orbits of 2007 OR10 and Eris.
A preliminary motion analysis of 2007 OR10 librating in a 3:10 resonance with Neptune. This animation consists of 16 frames covering 26,000 years.[5] Neptune (white dot) is held stationary.
Apparent motion of 2007 OR10 through the constellation Aquarius (years 2000 to 2050).

2007 OR10 orbits the Sun at an average distance of 67.4 AU and completes a full orbit in 553 years.[3] The orbit of 2007 OR10 is highly inclined to the ecliptic, with an orbital inclination 30.7 degrees.[3] Its orbit is also highly eccentric, with a measured orbital eccentricity of 0.503.[3] Due to its highly eccentric orbit, the distance of 2007 OR10 from the Sun varies greatly over the course of its orbit, from 101.3 AU at aphelion, its furthest point from the Sun, to around 33.5 AU at perihelion, its closest point to the Sun.[3][27] 2007 OR10 had approached its perihelion in 1857 and is currently moving farther from the Sun, toward its aphelion.[51]

The Minor Planet Center lists it as a scattered disc object for its eccentric and distant orbit.[4] The Deep Ecliptic Survey shows the orbit of 2007 OR10 to be in a 3:10 resonance with Neptune; 2007 OR10 completes three orbits around the Sun for every ten orbits completed by Neptune.[5]

As of July 2019, 2007 OR10 is located 88.2 AU (1.319×1010 km) from the Sun[52] and is moving away at a speed of 1.1 kilometers per second (2,500 miles per hour).[53] It is currently the sixth-farthest known Solar System object from the Sun, preceding 2015 TH367 (89.5 AU), 2014 UZ224 (90.4 AU), Eris (96.1 AU), 2018 VG18 (~ 120 AU),[54] and "FarFarOut" (~ 140 AU).[52][55][d] 2007 OR10 is currently more distant than Sedna, which is located 84.8 AU from the Sun as of July 2019.[52] It has been farther from the Sun than Sedna since 2013.[53] 2007 OR10 will be farther than both Sedna and Eris by 2045,[57] and will approach its aphelion in 2130.[53]

## Exploration

It was calculated that a flyby mission to 2007 OR10 could take just under 25 years using a Jupiter gravity assist, based on a launch date of 2030 or 2031. 2007 OR10 would be approximately 95 AU from the Sun when the spacecraft arrives.[58]

## Satellite

Discovery Hubble images of 2007 OR10 and its moon, taken in 2009 and 2010 with the Wide Field Camera 3.[59] Gábor MartonCsaba KissThomas Müller[e] 18 September 2010(announced 17 October 2016)[e] Epoch 8 December 2014 (JD 2457000.0) 24021±202 km (prograde), 24274±193 km (retrograde) 0.2908±0.007 (prograde), 0.2828±0.0063 (retrograde) 25.22073±0.000357 d (prograde), 25.22385±0.000362 d (retrograde) 83.08°±0.86° (prograde), 119.14°±0.89° (retrograde) 31.99°±1.07° (prograde), 104.09°±0.82° (retrograde) (225088) 2007 OR10 < 100 km[f]~237 km (assuming an albedo of 0.089)[49] > 0.2 V–I=1.22±0.17[9] 6.93±0.15[9]

2007 OR10 has a single known moon, S/2010 (225088) 1. It was first identified in 2016 by a team of astronomers led by Csaba Kiss, in archival images taken on 18 September 2010 with the Hubble Space Telescope. The discovery was announced on 17 October 2016.[27][60] S/2010 (225088) 1 is estimated to be less than 100 km (62 mi) in diameter, implying an albedo above 0.2.[9]

The absolute magnitude of the moon is estimated to be 6.93±0.15, at least 4.59 magnitudes dimmer than 2007 OR10 (given an absolute magnitude of 2.34 for the primary).[9]

It is not yet possible to determine whether the orbit of the satellite is prograde or retrograde.[9] Based on a prograde orbit model, the satellite orbits the primary at a distance of around 24,021 km (14,926 mi) and completes one orbit in 25.22 days.[g] The satellite is believed to be tidally locked to the primary.[9] Using the same prograde orbit model, the discovery team estimates that its orbit is inclined to the ecliptic by about 83 degrees. Assuming that the orbit has a low inclination to the primary's equator, this implies that 2007 OR10 is being viewed at a nearly pole-on configuration.[9] The moon's orbit has an eccentricity of 0.29.

### Observations

Hubble image sequence of 2007 OR10 and its satellite.

Following the March 2016 discovery that 2007 OR10 was an unusually slow rotator, the possibility was raised that a satellite may have slowed it down via tidal forces.[8] The indications of a possible satellite orbiting 2007 OR10 led Csaba Kiss and his team to analyze archival Hubble observations of 2007 OR10.[49] Their analysis of Hubble images taken on 18 September 2010 revealed a faint satellite orbiting 2007 OR10 at a distance of at least 15,000 km (9,300 mi).[48] Upon further analysis of archival images, the discovery team later also identified the satellite in Hubble images taken on 9 November 2009.[49] From these images taken in 2009 and 2010, the mean brightness difference between the satellite and the primary was calculated to be 4.34±0.26 magnitudes.[49] The discovery team was unable to determine the satellite's exact orbit from these two images.[50]

Further observations in 2017 with the Hubble Space Telescope's Wide Field Camera 3 were carried out to determine the orbit of the moon as well as the mass and density of 2007 OR10.[61][9] From these observations, the absolute magnitude of the moon was estimated at 6.93±0.15, at least 4.59 magnitudes dimmer than 2007 OR10 (given an absolute magnitude of 2.34 for the primary).[9]

### Orbit

Based on Hubble images of 2007 OR10 and its satellite taken in 2009 and 2010, the discovery team constrained the satellite's orbital period to between 20 and 100 days.[49] To further determine the orbit, they used Hubble in 2017 to observe the satellite's motion around 2007 OR10.

Because the observations of the satellite only span a small fraction of 2007 OR10's orbit around the Sun,[h] it is not yet possible to determine whether the orbit of the satellite is prograde or retrograde.[9] Based on a prograde orbit model, the satellite orbits the primary at a distance of around 24,021 km (14,926 mi) and completes one orbit in 25.22 days.[i] The satellite is believed to be tidally locked to the primary.[9] Using the same prograde orbit model, the discovery team estimates that its orbit is inclined to the ecliptic by about 83 degrees. Assuming that the orbit has a low inclination to the primary's equator, this implies that 2007 OR10 is being viewed at a pole-on configuration.[9]

The orbit of the moon is highly eccentric, with an eccentricity of 0.29. This high eccentricity is thought to be caused either by an intrinsically eccentric orbit and slow tidal evolution, or by the Kozai mechanism. The Kozai mechanism can be driven by perturbations either from the Sun's tidal forces, or from higher order terms in the gravitational potential of 2007 OR10 due to its oblate shape.[9] The dynamics of the moon's orbit are similar to that of Quaoar's satellite Weywot, which has a moderate eccentricity of about 0.14.[9]

### Physical characteristics

Based on dynamical models of the moon's orbit, it is estimated to be less than 100 km (62 mi) in diameter, implying an albedo above 0.2.[9] Upon its discovery, the satellite's diameter was initially estimated at 237 km (147 mi), under the assumption that the albedos of the satellite and the primary were equal.[49] Photometric measurements in 2017 show that the satellite is far less red than the primary.[9] The color difference of ΔV–I=0.43±0.17 between the primary (V–I=1.65±0.03) and satellite (V–I=1.22±0.17) is the largest among all known binary trans-Neptunian objects.[9] This large color difference is atypical for trans-Neptunian binary systems; the components of most trans-Neptunian binaries display little color variation, unlike the 2007 OR10 system.[9]

## Notes

1. ^ Discovery was announced two years later on 7 January 2009.
2. ^ The unaided human eye can detect objects with a visual magnitude of around +8 or lower.[40]
3. ^ The resulting minimum diameter of 580 km is derived from the equation ${\displaystyle E={\frac {1329}{\sqrt {p}}}10^{-0.2H}}$, where ${\displaystyle H}$ is the absolute magnitude of 2007 OR10, and ${\displaystyle p}$ is the albedo of 2007 OR10, which in this case is assumed to be 1.[36]
4. ^ A distant trans-Neptunian object, designated V774104, has been suspected in 2015 to be about 103 AU from the Sun. Due to its short observation arc, its orbit and distance have not been precisely measured.[56]
5. ^ a b The discoverers of S/2010 (225088) 1 began their analysis of archival Hubble images in 2016. The satellite was first identified in Hubble images taken on 18 September 2010, and was later reported and announced by Gábor Marton, Csaba Kiss, and Thomas Müller in the 48th Meeting of the Division for Planetary Sciences on 17 October 2016.[48][50][8]
6. ^ The minimum diameter is 36 km (radius 18 km), corresponding to an albedo of 1.[36] The 100 km corresponds to an albedo of 0.2.[9]
7. ^ The values in the retrograde model are similar.
8. ^ Less than 10 years, compared to 2007 OR10's orbital period of 553 years.
9. ^ The values in the retrograde model are similar, compare info box.

## References

1. ^ a b c "225088 (2007 OR10)". Minor Planet Center. Retrieved 5 March 2018.
2. ^ a b c "MPEC 2009-A42 : 2007 OR10". Minor Planet Center. 7 January 2009. Retrieved 23 May 2019.
3. "JPL Small-Body Database Browser: 225088 (2007 OR10)" (2015-09-20 last obs.). Jet Propulsion Laboratory. Retrieved 23 May 2019.
4. ^ a b "List Of Centaurs and Scattered-Disk Objects". Minor Planet Center. Retrieved 9 February 2018.
5. ^ a b c Buie, M. (24 May 2019). "Orbit Fit and Astrometric record for 225088". SwRI (Space Science Department). Archived from the original on 24 May 2019. Retrieved 24 May 2019.
6. ^ Johnston, Wm. Robert (7 October 2018). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 23 May 2019.
7. Brown, Michael E. (20 May 2019). "How many dwarf planets are there in the outer solar system?". California Institute of Technology. Retrieved 23 May 2019.
8. ^ a b c d Lakdawalla, E. (19 October 2016). "DPS/EPSC update: 2007 OR10 has a moon!". The Planetary Society. Retrieved 19 October 2016.
9. Kiss, Csaba; Marton, Gabor; Parker, Alex H.; Grundy, Will; Farkas-Takacs, Aniko; Stansberry, John; Pal, Andras; Muller, Thomas; Noll, Keith S.; Schwamb, Megan E.; Barr, Amy C.; Young, Leslie A.; Vinko, Jozsef (October 2018). "The mass and density of the dwarf planet (225088) 2007 OR10". Icarus: 311.02. arXiv:1903.05439. Bibcode:2018DPS....5031102K. doi:10.1016/j.icarus.2019.03.013.
Initial publication at the American Astronomical Society DPS meeting #50, with the publication ID 311.02
10. Pál, András; Kiss, Csaba; Müller, Thomas G.; Molnár, László; Szabó, Róbert; Szabó, Gyula M.; et al. (May 2016). "Large Size and Slow Rotation of the Trans-Neptunian Object (225088) 2007 OR10 Discovered from Herschel and K2 Observations". The Astronomical Journal. 151 (5): 8. arXiv:1603.03090. Bibcode:2016AJ....151..117P. doi:10.3847/0004-6256/151/5/117.
11. ^ a b c Szabó, Róbert (4 November 2015). "Pushing the Limits of K2:Observing Trans-Neptunian Objects S3K2: Solar System Studies with K2" (PDF). Retrieved 19 January 2018.
12. ^ a b Boehnhardt, H.; Schulz, D.; Protopapa, S.; Götz, C. (November 2014). "Photometry of Transneptunian Objects for the Herschel Key Program 'TNOs are Cool'". Earth, Moon, and Planets. 114 (1–2): 35–57. Bibcode:2014EM&P..114...35B. doi:10.1007/s11038-014-9450-x.
13. ^ a b "LCDB Data for (225088)". Asteroid Lightcurve Database (LCDB). Retrieved 14 May 2019.
14. ^ "AstDys 2007OR10 Observation prediction". Department of Mathematics, University of Pisa, Italy. Archived from the original on 24 May 2019. Retrieved 24 May 2019.
15. ^ "RESOLUTION B5 - Definition of a Planet in the Solar System" (PDF). International Astronomical Union. 2006. Retrieved 26 May 2019.
16. Brown, M. E.; Burgasser, A. J.; Fraser, W. C. (September 2011). "The Surface Composition of Large Kuiper Belt Object 2007 OR10" (PDF). The Astrophysical Journal Letters. 738 (2): 4. arXiv:1108.1418. Bibcode:2011ApJ...738L..26B. doi:10.1088/2041-8205/738/2/L26. Retrieved 5 March 2018.
17. Brown, Michael E. (10 March 2009). "Snow White needs a bailout". Archived from the original on 17 May 2009. Retrieved 17 February 2010.
18. ^ Schwamb, Megan E.; Brown, Michael E.; Rabinowitz, David L. (2009). "A Search for Distant Solar System Bodies in the Region of Sedna". Astrophysical Journal Letters. 694 (1): L45–L48. arXiv:0901.4173. Bibcode:2009ApJ...694L..45S. doi:10.1088/0004-637X/694/1/L45.
19. Schwamb, Megan (9 April 2019). "2007 OR10 Needs a Name!". The Planetary Society. Archived from the original on 24 May 2019. Retrieved 24 May 2019.
20. ^ a b Schwamb, Megan E.; Brown, Michael E.; Rabinowitz, David L.; Ragozzine, Darin (25 August 2010). "Properties of the Distant Kuiper Belt: Results from the Palomar Distant Solar System Survey". The Astrophysical Journal Letters. 720 (2): 1691–1707. arXiv:1007.2954. Bibcode:2010ApJ...720.1691S. doi:10.1088/0004-637X/720/2/1691.
21. ^ a b Brown, Michael E. (29 November 2010). "There's something out there -- part 3". Retrieved 10 May 2019.
22. "Astronomers Find Ice and Possibly Methane On Snow White, a Distant Dwarf Planet". Science Daily. 22 August 2011. Retrieved 5 March 2018.
23. ^ "New- And Old-Style Minor Planet Designations". Minor Planet Center. Retrieved 10 May 2019.
24. ^ a b Lowe, Andrew. "(225088) 2007 OR10 Precovery Images". Retrieved 6 May 2019.
25. Dyches, P. (11 May 2016). "2007 OR10: Largest Unnamed World in the Solar System". Jet Propulsion Laboratory. Retrieved 12 May 2016.
26. ^ a b c d Brown, Michael E. (9 August 2011). "The Redemption of Snow White (Part 1)". Mike Brown's Planets.
27. "Help Name 2007 OR10". Archived from the original on 25 May 2019. Retrieved 9 April 2019.
28. ^ a b c "How Are Minor Planets Named?". Minor Planet Center. Retrieved 8 May 2019.
29. ^ Plotner, Tammy (3 August 2011). ""Snow White" or "Rose Red" (2007 OR10)". Universe Today. Retrieved 8 May 2019.
30. ^ "Astronomers Invite the Public to Help Name Kuiper Belt Object". IAU. 10 April 2019. Retrieved 12 May 2019.
31. ^ a b c d Schwamb, Megan (29 May 2019). "The People Have Voted on 2007 OR10's Future Name!". The Planetary Society. Retrieved 29 May 2019.
32. ^ a b c Brown, Michael E. (May 2012). "The compositions of Kuiper belt objects" (PDF). Annual Reviews. 40 (1): 467–494. arXiv:1112.2764. Bibcode:2012AREPS..40..467B. doi:10.1146/annurev-earth-042711-105352. Retrieved 19 May 2019.
33. ^ a b c Santos-Sanz, P.; et al. (2012). ""TNOs are Cool": A survey of the trans-Neptunian region. IV. Size/albedo characterization of 15 scattered disk and detached objects observed with Herschel-PACS". Astronomy & Astrophysics. 541: A92. arXiv:1202.1481. Bibcode:2012A&A...541A..92S. doi:10.1051/0004-6361/201118541.
34. ^ Brown, M. E.; Schaller, E. L.; Fraser, W. C. (14 May 2012). "The compositions of Kuiper belt objects" (PDF). The Astrophysical Journal. 143 (6). arXiv:1204.3638. doi:10.1088/0004-6256/143/6/146. Retrieved 19 May 2019.
35. Brown, Michael E. (20 August 2011). "The Redemption of Snow White (Part 3 of 3)". Mike Brown's Planets. Archived from the original on 25 July 2014.
36. ^ a b c "Conversion of Absolute Magnitude to Diameter for Minor Planets". physics.sfasu.edu. Retrieved 14 May 2019.
37. ^ Brown, Michael E. (11 August 2011). "The Redemption of Snow White (Part 2 of 3)". Mike Brown's Planets. Archived from the original on 25 July 2014.
38. ^ Pál, A.; Kiss, C.; Müller, T. G.; Santos-Sanz, P.; Vilenius, E.; Szalai, N.; Mommert, M.; Lellouch, E.; Rengel, M.; Hartogh, P.; Protopapa, S.; Stansberry, J.; Ortiz, J. -L.; Duffard, R.; Thirouin, A.; Henry, F.; Delsanti, A. (2012). ""TNOs are Cool": A survey of the trans-Neptunian region. VII. Size and surface characteristics of (90377) Sedna and 2010 EK139". Astronomy & Astrophysics. 541: L6. arXiv:1204.0899. Bibcode:2012A&A...541L...6P. doi:10.1051/0004-6361/201218874.
39. ^ Fornasier, S.; Lellouch, E.; Müller, T.; Santos-Sanz, P.; Panuzzo, P.; Kiss, C.; et al. (July 2013). "TNOs are Cool: A survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of 9 bright targets at 70–500 µm". Astronomy & Astrophysics. 555 (A15): 22. arXiv:1305.0449v2. Bibcode:2013A&A...555A..15F. doi:10.1051/0004-6361/201321329.
40. ^ Sinnott, Roger W. (19 July 2006). "What's my naked-eye magnitude limit?". Sky and Telescope. Retrieved 17 April 2019.
41. ^ "AstDys Sedna Observation prediction". Department of Mathematics, University of Pisa, Italy. Archived from the original on 24 May 2019. Retrieved 24 May 2019.
42. ^ a b c Johnson, R. E.; Oza, A.; Young, L. A.; Volkov, A. N.; Schmidt, C. (7 August 2015). "Volatile Loss and Classification of Kuiper Belt Objects". The Astrophysical Journal. 809 (1): 43. arXiv:1503.05315. Bibcode:2015ApJ...809...43J. doi:10.1088/0004-637X/809/1/43.
43. ^ a b Tancredi, Gonzalo (6 April 2010). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Proceedings of the International Astronomical Union. 5 (S263): 173–185. Bibcode:2010IAUS..263..173T. doi:10.1017/S1743921310001717. Retrieved 14 May 2019.
44. ^ a b Lellouch, E.; Santos-Sanz, P.; Lacerda, P.; Mommert, M.; Duffard, R.; Ortiz, J. L.; et al. (September 2013). ""TNOs are Cool": A survey of the trans-Neptunian region. IX. Thermal properties of Kuiper belt objects and Centaurs from combined Herschel and Spitzer observations" (PDF). Astronomy and Astrophysics. 557: 19. arXiv:1202.3657. Bibcode:2013A&A...557A..60L. doi:10.1051/0004-6361/201322047. Retrieved 27 April 2019.
45. ^ a b Stern, S. A.; Grundy, W.; McKinnon, W. B.; Weaver, H. A.; Young, L. A. (15 December 2017). "The Pluto System After New Horizons". Annual Review of Astronomy and Astrophysics. 56: 357–392. arXiv:1712.05669. doi:10.1146/annurev-astro-081817-051935.
46. ^ Braga-Ribas, F.; Sicardy, B.; Ortiz, J. L.; Lellouch, E.; Tancredi, G.; Lecacheux, J.; et al. (August 2013). "The Size, Shape, Albedo, Density, and Atmospheric Limit of Transneptunian Object (50000) Quaoar from Multi-chord Stellar Occultations". The Astrophysical Journal. 773 (1): 13. Bibcode:2013ApJ...773...26B. doi:10.1088/0004-637X/773/1/26.
47. ^ a b Sheppard, Scott S.; Udalski, Andrzej; Trujillo, Chadwick; Kubiak, Marcin; Pietrzynski, Grzegorz; Poleski, Radoslaw; et al. (October 2011). "A Southern Sky and Galactic Plane Survey for Bright Kuiper Belt Objects". The Astronomical Journal. 142 (4): 10. arXiv:1107.5309. Bibcode:2011AJ....142...98S. doi:10.1088/0004-6256/142/4/98.
48. ^ a b c "The moon of the large Kuiper-belt object 2007 OR10" (PDF). DPS48 120.22. 2016. Retrieved 24 May 2019.
49. Kiss, Csaba; Marton, Gábor; Farkas-Takács, Anikó; Stansberry, John; Müller, Thomas; Vinkó, József; Balog, Zoltán; Ortiz, Jose-Luis; Pál, András (16 March 2017). "Discovery of a Satellite of the Large Trans-Neptunian Object (225088) 2007 OR10". The Astrophysical Journal Letters. 838 (1): L1. arXiv:1703.01407. Bibcode:2017ApJ...838L...1K. doi:10.3847/2041-8213/aa6484.
50. ^ a b c "Moon orbits third largest dwarf planet in our solar system". Science Daily. 18 May 2017. Retrieved 19 May 2017.
51. ^ "Asteroid 2007 OR10". The Sky Live. Retrieved 7 May 2019.
52. ^ a b c "AstDyS-2, Asteroids - Dynamic Site". Retrieved 3 July 2019. Objects with distance from Sun over 84.2 AU
53. ^ a b c "Horizon Online Ephemeris System". Jet Propulsion Laboratory. Retrieved 31 January 2012.
54. ^ "Discovered: The Most-Distant Solar System Object Ever Observed". Carnegie Science. 17 December 2018. Retrieved 7 May 2019.
55. ^ Voosen, Paul (21 February 2019). "Astronomers Discover Solar System's Most Distant Object, Nicknamed 'FarFarOut'". Science. doi:10.1126/science.aax1154.
56. ^ Cofield, Calla (12 November 2015). "New Dwarf Planet In Our Solar System May Be The Farthest One Yet". Space.com. Retrieved 7 May 2019.
57. ^ "Horizons Output for Sedna 2076/2114". JPL Horizons On-Line Ephemeris System. 17 February 2011. Archived from the original on 25 February 2012. Retrieved 17 February 2011.
58. ^ Zangari, Amanda M.; Finley, Tiffany J.; Stern, S. Alan; Tapley, Mark B. (2018). "Return to the Kuiper Belt: Launch Opportunities from 2025 to 2040". Journal of Spacecraft and Rockets. 56 (3): 919–930. arXiv:1810.07811. doi:10.2514/1.A34329.
59. ^ "Moon Around the Dwarf Planet 2007 OR10". www.spacetelescope.org. Retrieved 22 May 2017.
60. ^ Johnston, Wm. Robert (22 October 2016), (225088) 2007 OR10, retrieved 11 June 2019
61. ^ Parker, Alex (7 April 2017). "The Moons of Kuiper Belt Dwarf Planets Makemake and 2007 OR10 HST Proposal 15207". Mikulski Archive for Space Telescope. Space Telescope Science Institute. Retrieved 21 September 2018.