(225088) Gong gong

Asteroid (225088) Gong gong
(225088) Gonggong and his moon Xiangliu (red circle) through the Hubble Space Telescope (2010)
Properties of the orbit ( animation ) Epoch:  April 27, 2019 ( JD 2,458,600.5)
Orbit type	RKBO 3:10 or SDO , "Distant Object"
Major semi-axis	67.376  AU
eccentricity	0.503
Perihelion - aphelion	33.494 AU - 101.258 AU
Inclination of the orbit plane	30.7 °
Length of the ascending node	336.8 °
Argument of the periapsis	207.5 °
Time of passage of the perihelion	August 7, 1857
Sidereal period	553 a 0.6 M
Mean orbital velocity	3.599 km / s
Physical Properties
Medium diameter	${\displaystyle 1230_{-50}^{+50}\mathrm {km} }$
Dimensions	1.75  x  10 21 kg
Albedo	${\displaystyle 0{,}089_{-0,009}^{+0,031}\mathrm {} }$
Medium density	1.75 ± 0.07 g / cm³
Rotation period	44.81 h 49 min or 22 h 24 min
Absolute brightness	1.80 - 2.34 mag
Spectral class	C B-V = 1.380 ± 0.030 VR = 0.860 ± 0.020 VI = 1.650 ± 0.028
history
Explorer	Megan E. Schwamb Michael E. Brown David L. Rabinowitz
Date of discovery	July 17, 2007
Another name	(225088) 2007 OR 10
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

(225088) Gonggong , provisional designation (225088) 2007 OR ₁₀ , is one of the largest known Trans-Neptunian objects (TNO). In terms of path dynamics, it is classified as a resonant Kuiper belt object (RKBO) or as a scattered disk object (SDO). The asteroid Gonggong is a dwarf planet candidate and features a moon named Xiangliu .

Discovery and naming

Gong Gong on July 17, 2007 by a team of astronomers consisting of Meg Schwamb, Mike Brown and Dave Rabinowitz of the California Institute of Technology (CalTech), the 1.2-m Oschin Schmidt telescope of the Palomar Observatory ( California discovered) . The discovery came as part of a search for new properties in the Sedna area as part of the PhD thesis of Megan E. Schwamb, who was an academy student with Mike Brown at the time. Brown gave the asteroid nicknamed "Snow White" ( Snow White ) due to its bright appearance after not materialize get his former opinion because of its size but because of its white color. Later it turned out that it has a strong reddish color, so that the name turned out to be inappropriate. 2007 OR ₁₀ was the ninth discovery of a large TNO and likely dwarf planet by Mike Brown's team of astronomers. Brown's team successively discovered Quaoar and 2002 MS4 (2002), Sedna (2003), Haumea (2003, controversial), Orcus and Salacia (2004), and the dwarf planets Makemake and Eris (2005).

The discovery was formally announced on January 7, 2009. In August 2011, Brown posted on the Internet that he had enough information about the asteroid to warrant a name, since the discovery of water ice and the possibility of methane made the object “sufficiently remarkable” for further studies. In April 2017, Brown - who had not yet submitted a name proposal - posted that name suggestions would be open to everyone from November 2019. On February 5, 2020, the asteroid was named (225088) Gonggong after the demon Gonggong from Chinese mythology.

After his discovery, (225088) Gonggong could be identified in photos taken as part of the Digitized Sky Survey (DSS) at the European Southern Observatory's La Silla Observatory up to August 19, 1985, and thus extended his observation sheet by 22 years ; this allowed its orbit to be calculated more precisely. Since then, the asteroid has been observed through various telescopes such as the Hubble , Herschel, and Kepler Space Telescopes, and earth-based telescopes such as the Keck and Palomar observatories . In April 2017, there were 230 observations over a period of 31 years from 13 oppositions. The last observation so far was made in September 2015 at the Calar Alto Observatory . (As of March 4, 2019)

Track properties

The orbit of (225088) Gonggong (yellow) compared to Eris (green), Pluto (purple) and other distant planetoids (white) as well as the giant planets.

Orbit

(225088) Gonggong orbits the sun in a highly elliptical orbit between 33.49  AU and 101.27 AU from its center. The orbital eccentricity is 0.503, the web is 30.739 ° relative to the ecliptic inclined . The orbital period is 553.05 years. This is comparable to the orbital period of the dwarf planet Eris (557.55 years).

Gonggong last reached perihelion in 1857 and is currently moving away from the sun; In 2013 it surpassed Sedna in distance. The planetoid is currently 88.20 AU from the Sun; seen from earth, it is roughly in the direction of the galactic center . This makes it after 2018 VG ₁₈ (124.8 AU) and Eris (96.4 AU) - and before 2012 VP ₁₁₃ (83.6 AU) - the currently third most distant known large object in the solar system. In 2045 he will overtake Eris. His aphelion will reach OR ₁₀ in 2007 in 2132; the next perihelion will occur in 2410.

classification

The Deep Ecliptic Survey classifies the orbit in a 3:10 resonance with Neptune , but this has not yet been independently confirmed and secured; it could just be a near-resonance. In the first case (225088) Gonggong would be a resonant KBO (RKBO). The Minor Planet Center classifies the object as SDO / Centaur and also as a "Distant Object", which is why it has not yet been clearly classified.

Physical Properties

size

By combining Kepler and Herschel, the first calculations could be improved. Kepler made it possible to determine which fraction of the sunlight is reflected and to determine the period of rotation. Herschel was able to measure which part of the light is absorbed and emitted again as thermal radiation. These data together allowed a more precise determination of the size and the reflectance. A group of Hungarian astronomers also examined (225088) gong gong as part of the Kepler K2 program and determined a rotation period of 44.81 hours. They determined the albedo to be 0.089  ^+0.031_−0.009, resulting in a diameter of 1535  ⁺⁷⁵₋₂₂₅ km can be derived. This would make the Gonggong much darker and larger than originally assumed. The planetoid would be bigger than Makemake and maybe Haumea and definitely a dwarf planet. In 2019, a smaller diameter of 1230 ± 50 km was determined again. The discovery of the moon does not seem to have any significant influence on the determination of the size of the mother planetoid. The apparent brightness of the gong gong is 21.46  ^m .

The mass of (225088) Gonggong is estimated to be about 1.75  ·  10 ²¹  kg and it can be assumed that, based on the available data, it fulfills the criteria and should be classified as a dwarf planet. According to Mike Brown it must almost certainly be a dwarf planet, according to Scott Sheppard it is only likely one. Gonzalo Tancredi did not make a recommendation in 2010, despite a comparatively high diameter of 1752 km that he calculated.

Determination of the diameter for 2007 OR ₁₀

year	Dimensions km	source
2010	1752.0	Tancredi
2011	1200.0   +300.0−200.0	Brown et al. a.
2012	1280.0 ± 210.0	Santos-Sanz et al. a.
2013	1142.0   +647.0−467.0	Lellouch u. a.
2015	1535.0   +75.0−225.0	Szabó u. a.
2016	1834.53	LightCurve DataBase
2017	1520.0	Kiss u. a.
2018	1290.0	Brown
2019	1230.0 ± 50	Kiss u. a.
The most precise determination is marked in bold .

rotation

Based on a rotation period of 44.81 hours rsp. 1.867 days it results that the planetoid performs 108,191.6 self- rotations ("days") in a gong gong year . According to an earlier study from 2009, he would only need about half as long with 22.40 hours, which would practically double the number of gong gong days in his year with 216,431.5 revolutions. The latter variant, however, is considered to be rather unlikely, especially since the error rate is around 30% and the observation time at that time was insufficient.

internal structure

According to Mike Brown's team of explorers, the structure of Gonggong probably consists of a rock core with a thick coat of water ice , the calculation of which is based on the observation data and an assumed density of 2.0 g / cm³.

Fantasy representation of a possible view of the surface.

surface

Spectral examinations showed high amounts of water ice on at least half of the surface. There are also spectral traces of methane , which is in the form of a thin layer of frozen methane with a strong reddish color over the ice cover. According to Mike Brown, the planetoid has one of the reddest surfaces in the solar system, which is a stark contrast to the abundant water ice. In this composition (225088) Gonggong is similar to that of Quaoar. The red color could be explained by the reaction of the thin methane ice layer to the bombardment by particles of the solar wind and cosmic rays.

Assuming a diameter of 1535 km, the total area is about 7,360,000 km² and thus roughly corresponds to the area of Australia including New Zealand . (225088) The gong gong is the sixth brightest known trans-Neptunian object. At 1.8 ^{m it is a} little darker than Sedna (1.5 ^m ) and a little lighter than Orcus (2.2 ^m ).

Mike Brown's team of explorers assumes that the surface underwent a brief period of transformations through cryovolcanic processes after the formation phase around 4 billion years ago .

Possible atmosphere

The presence of a layer of red methane frost - presumably remnants of a former atmosphere - on the surface of (225088) Gonggong indicates the existence of a weak methane atmosphere that is slowly evaporating into the surrounding space. Although Gonggong comes closer to the sun than Quaoar and therefore becomes warm enough for a methane layer to sublime , its larger mass can more easily hold a weak atmosphere.

moon

(225088) Gonggong and Xiangliu

→ Main article : Xiangliu (moon)

On October 17, 2016, the discovery of a moon at (225088) Gonggong was announced. The discovery is based on images from the Hubble Space Telescope, which were taken in September 2010. The moon known as Xiangliu has a diameter of roughly 300 kilometers. Its distance from the main body is given as at least 15,000 kilometers. Further observations are necessary to determine more precise orbit data (orbital time and actual orbit radius); the mass of the system could be determined more precisely from such data.

The (225088) Gong gong system at a glance:

Components	Physical parameters			Path parameters				discovery
Surname	Throughput diameter (km)	Relative size %	Mass (kg)	Major semi-axis (km)	Orbital time (d)	eccentricity	Inclination to 2007 OR 10 equator	Date of discovery Date of publication
(225088) Gong gong	1230	100.0	1.75  ·  10 21	-	-	-	-	July 17, 2007 January 7, 2009 0
Xiangliu (225088 Gonggong I)	<100.0	8th	?	15000	6.0	?	?	September 18, 2010 October 17, 2016

See also

• List of trans-Neptunian objects
• List of dwarf planets of the solar system
• List of asteroids
• List of moons from asteroids

Web links

Commons : (225088) Gonggong  - collection of pictures, videos and audio files

• Precovery photos of (225088) Gonggong
• 2007 OR10 significantly larger than expected? - Article on Astronews.com (May 12, 2016)
• How many dwarf planets are there in the outer solar system? Current list of the largest TNOs from Mike Brown
• Free the dwarf planets! Mike Brown's column on the IAU and the dwarf planets regarding their classifications (23 August 2011)

Individual evidence

1. ↑ ^{a b} M. Buie : Orbit Fit and Astrometric record for 225088. SwRI (Space Science Department), accessed on March 4, 2019 .  
2. ↑ ^{a b} MPC : List Of Centaurs and Scattered-Disk Objects . IAU . Retrieved March 4, 2019.
3. ↑ ^{a b c} (225088) Gonggong at the IAU Minor Planet Center (English) Retrieved on March 4, 2019.
4. ↑ v ≈ π * a / period (1 + sqrt (1-e²))
5. ↑ ^{a b c d e f g} C. Kiss, G. Marton, AH Parker, W. Grundy, A. Farkas-Takacs, J. Stansberry, A. Pal, T. Muller, KS Noll, ME Schwamb, AC Barr, LA Young, J. Vinko: The mass and density of the dwarf planet (225088) 2007 OR ₁₀ . In: Icarus . 334, 2019, pp. 3–10. arxiv : 1903.05439 . 311.02. 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
6. ↑ ^{a b c d} R. Szabó u. a: Pushing the Limits of K2: Observing Trans-Neptunian Objects. S3K2: Solar System Studies with K2 (PDF). Retrieved February 9, 2019 .  
7. ↑ ^{a b c d} A. Pál u. a .: Large size and slow rotation of the trans-Neptunian object (225088) 2007 OR10 discovered from Herschel and K2 observations (PDF) . In: The Astronomical Journal . 151, No. 5, April 19, 2016, p. 117. arxiv : 1202.1481 . bibcode : 2012A & A ... 541A..92S . doi : 10.1051 / 0004-6361 / 201118541 .
8. ↑ ^{a b} LCDB Data for 2007 OR10 . MinorPlanetInfo. October 2016. Retrieved March 4, 2019.
9. ↑ ^{a b c} H. Boehnhardt u. a .: Photometry of Transneptunian Objects for the Herschel Key Program “TNOs are Cool” . In: Earth, Moon, and Planets . 114, No. 1-2, November 2014, pp. 35-57. bibcode : 2014EM & P..114 ... 35B . doi : 10.1007 / s11038-014-9450-x .
10. ^ ^{A b} M. Brown : The redemption of Snow White (Part 1). In: mikebrownsplanets.com. August 9, 2011, accessed March 4, 2019 .  
11. ↑ MPC : MPEC 2009-A42: 2007 OR10 . IAU . January 7, 2009. Retrieved March 4, 2019.
12. ^ M. Brown : Twitter. April 10, 2017, accessed March 4, 2019 . 
13. ↑ (225088) Gong gong = 2007 OR10 . Minor Planet Center . February 5, 2020, accessed on February 22, 2020.
14. ↑ ^{a b} Michele Johnson: 2007 OR10: Largest Unnamed World in the Solar System. In: NASA. May 11, 2016, accessed March 4, 2019 . 
15. ↑ ^{a b} (225088) Gonggong in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved March 4, 2019.
16. ↑ Philip Sedgwick: Dwarf Planet 2007 OR ₁₀ is now Minor Planet 225088. November 4, 2009, accessed March 4, 2019 .  
17. ↑ (225088) Gong gong in the database of the "Asteroids - Dynamic Site" (AstDyS-2, English).
18. ^ ^{A b} G. Tancredi: Physical and dynamical characteristics of icy “dwarf planets” (plutoids) . IAU. April 1, 2010. Retrieved March 4, 2019.
19. ↑ ^{a b c} M. Brown et al. a .: The Surface Composition of Large Kuiper Belt Object 2007 OR10 (PDF) . In: The Astrophysical Journal Letters . 738, No. 2, August 5, 2011, p. L26. arxiv : 1108.1418 . bibcode : 2011ApJ ... 738L..26B . doi : 10.1088 / 2041-8205 / 738/2 / L26 .
20. ↑ P. Santos-Sanz et al. a .: “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 (PDF) . In: Astronomy and Astrophysics . 541, No. A92, May 4, 2012, p. 18. arxiv : 1202.1481 . bibcode : 2012A & A ... 541A..92S . doi : 10.1051 / 0004-6361 / 201118541 .
21. ↑ E. Lellouch et al. a .: “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) . In: Astronomy and Astrophysics . 557, No. A60, June 10, 2013, p. 19. bibcode : 2013A & A ... 557A..60L . doi : 10.1051 / 0004-6361 / 201322047 .
22. ^ C. Kiss, J. Stansberry: Moon Around the Dwarf Planet 2007 OR10 (May 2017). Retrieved February 9, 2019 . 
23. ↑ M. Brown : How many dwarf planets are there in the outer solar system? . CalTech . November 12, 2018. Retrieved March 4, 2019.
24. ^ M. Brown : The redemption of Snow White (Part 3). In: mikebrownsplanets.com. August 9, 2011, accessed March 4, 2019 .  
25. ↑ Emily Lakdawalla: DPS / EPSC update: 2007 OR10 has a moon! The Planetary Society , October 19, 2016, accessed March 4, 2019 . 
26. ↑ Asteroids with Satellites - (225088) 2007 OR10. In: Asteroids with Satellites Database - Johnston's Archive. October 22, 2016, accessed March 4, 2019 . 
27. ↑ W. Grundy: 225088 (2007 OR10) . Lowell Observatory . January 21, 2019. Retrieved March 4, 2019.
28. ↑ ^{a b} Kelly Beatty: Big Kuiper Object 2007 OR ₁₀ Has a Moon. Sky & Telescope , October 21, 2016, accessed March 4, 2019 . 
29. ↑ C. Kiss et al. a: Discovery of a satellite of the large trans-neptunian object (225088) 2007 OR ₁₀ . In: Astrophysical Journal Letters . 838, No. 1, March 16, 2017, p. L1, 5. arxiv : 1703.01407 . doi : 10.3847 / 2041-8213 / aa6484 .