Summary
(52768) 1998 OR2 (provisional designation 1998 OR2) is an asteroid on an eccentric orbit, classified as a near-Earth object and potentially hazardous asteroid of the Amor group, with a diameter of 2 kilometers (1.2 mi). It was discovered on 24 July 1998, by astronomers of the Near-Earth Asteroid Tracking (NEAT) program at the Haleakala Observatory, Hawaii.[3] It is one of the brightest and therefore largest potentially hazardous asteroids known to exist.[7] With an observation arc of 35 years, the asteroid has a well-determined orbit, and its trajectory is well known through the year 2197.[2] The asteroid's orbit is only potentially hazardous on a time scale of thousands of years.[8]
 Arecibo Observatory radar image of 1998 OR2 with a crater on 18 April 2020 | |
| Discovery[2][3] | |
|---|---|
| Discovered by | NEAT |
| Discovery site | Haleakala Obs. |
| Discovery date | 24 July 1998 |
| Designations | |
| (52768) 1998 OR2 | |
| 1998 OR2 | |
| Amor · NEO · PHA[2][3] | |
| Orbital characteristics[2] | |
| Epoch 25 February 2023 (JD 2460000.5 ) | |
| Uncertainty parameter 0 | |
| Observation arc | 35.49 yr (12,963 days) |
| Earliest precovery date | 30 June 1987 (Siding Spring Obs.) |
| Aphelion | 3.750 AU |
| Perihelion | 1.011 AU |
| 2.380 AU | |
| Eccentricity | 0.5754 |
| 3.67 yr (1,342 days) | |
| 280.159° | |
| 0° 16m 6.082s / day | |
| Inclination | 5.878° |
| 26.942° | |
| 174.580° | |
| Earth MOID | 0.00866 AU (3.37 LD) |
| Physical characteristics[1]: 6 | |
| Dimensions | 2.08 × 1.93 × 1.60 km (± 0.10 × 0.10 × 0.03 km) |
Mean diameter | 1.78±0.10 km |
| 10.67 km2 | |
| Volume | 3.0±0.5 km3 |
Mean density | 3.2±0.2 g/cm3 |
| 4.10872±0.00001 h | |
| 69.3°±5° (wrt ecliptic)[a] | |
Pole ecliptic latitude | 20.7°±5° |
Pole ecliptic longitude | 332.3°±5° |
| 0.15[5] | |
| Xn or S[5] | |
| 15.72±0.02[6] 16.04[2][3] | |
Orbit and classification edit
1998 OR2 is a member of the dynamical Amor group of near-Earth asteroids,[2][3] and therefore does not currently cross Earth's orbit. The asteroid's closest approach to the Sun is just outside Earth's farthest distance from the Sun. When the asteroid has a perihelion point less than 1.017 AU (Earth's aphelion), it is classified an Apollo asteroid. This asteroid's category flips back and forth as time passes, due to minor perturbations of its orbit.
It orbits the Sun at a distance of 1.0–3.7 AU once every 3 years and 8 months (1,344 days; semi-major axis of 2.38 AU). Its orbit has a high eccentricity of 0.57 and an inclination of 6° with respect to the ecliptic. With its sufficiently large aphelion, this asteroid is also classified as a Mars-crosser, crossing the orbit of Mars at 1.66 AU.[2]
The body's observation arc begins with a precovery published by the Digitized Sky Survey taken at the Siding Spring Observatory in June 1986, more than 12 years prior to its official discovery observation at Haleakala Observatory, Hawaii.[3]
Close approaches edit
With an absolute magnitude of approximately 15.8,[3] 1998 OR2 is one of the brightest and presumably largest-known potentially hazardous asteroids (see PHA-list).[7] It currently has an Earth minimum orbital intersection distance of 0.0087 AU (1,300,000 km), which translates into 3.4 lunar distances (LD).[2] On 16 April 2079, this asteroid will make a near-Earth encounter at a safe distance of 0.0118 AU (4.59 LD), and pass the Moon at 0.0092 AU (3.6 LD).[2] The asteroid's orbit is only potentially hazardous on a time scale of hundreds, if not thousands, of years.
On 29 April 2020 at 09:56 UTC, the asteroid passed at a distance of 0.042 AU (6.3 million km; 16 LD) from Earth.[2] With observations as recent as April 2020 and a 32-year observation arc, the 2020 close approach distance was known with an accuracy of roughly ±6 km.[9] (For comparison, Venus will be 0.29 AU or 43 million km or 110 LD from Earth on 3 June 2020.)
| PHA | Date | Approach distance (lunar dist.) | Abs. mag (H) |
Diameter (C) (m) |
Ref (D) | ||
|---|---|---|---|---|---|---|---|
| Nomi- nal(B) |
Mini- mum |
Maxi- mum | |||||
| (33342) 1998 WT24 | 1908-12-16 | 3.542 | 3.537 | 3.547 | 17.9 | 556–1795 | data |
| (458732) 2011 MD5 | 1918-09-17 | 0.911 | 0.909 | 0.913 | 17.9 | 556–1795 | data |
| (7482) 1994 PC1 | 1933-01-17 | 2.927 | 2.927 | 2.928 | 16.8 | 749–1357 | data |
| 69230 Hermes | 1937-10-30 | 1.926 | 1.926 | 1.927 | 17.5 | 668–2158 | data |
| 69230 Hermes | 1942-04-26 | 1.651 | 1.651 | 1.651 | 17.5 | 668–2158 | data |
| (137108) 1999 AN10 | 1946-08-07 | 2.432 | 2.429 | 2.435 | 17.9 | 556–1795 | data |
| (33342) 1998 WT24 | 1956-12-16 | 3.523 | 3.523 | 3.523 | 17.9 | 556–1795 | data |
| (163243) 2002 FB3 | 1961-04-12 | 4.903 | 4.900 | 4.906 | 16.4 | 1669–1695 | data |
| (192642) 1999 RD32 | 1969-08-27 | 3.627 | 3.625 | 3.630 | 16.3 | 1161–3750 | data |
| (143651) 2003 QO104 | 1981-05-18 | 2.761 | 2.760 | 2.761 | 16.0 | 1333–4306 | data |
| 2017 CH1 | 1992-06-05 | 4.691 | 3.391 | 6.037 | 17.9 | 556–1795 | data |
| (170086) 2002 XR14 | 1995-06-24 | 4.259 | 4.259 | 4.260 | 18.0 | 531–1714 | data |
| (33342) 1998 WT24 | 2001-12-16 | 4.859 | 4.859 | 4.859 | 17.9 | 556–1795 | data |
| 4179 Toutatis | 2004-09-29 | 4.031 | 4.031 | 4.031 | 15.3 | 2440–2450 | data |
| 2014 JO25 | 2017-04-19 | 4.573 | 4.573 | 4.573 | 17.8 | 582–1879 | data |
| (137108) 1999 AN10 | 2027-08-07 | 1.014 | 1.010 | 1.019 | 17.9 | 556–1795 | data |
| (35396) 1997 XF11 | 2028-10-26 | 2.417 | 2.417 | 2.418 | 16.9 | 881–2845 | data |
| (154276) 2002 SY50 | 2071-10-30 | 3.415 | 3.412 | 3.418 | 17.6 | 714–1406 | data |
| (164121) 2003 YT1 | 2073-04-29 | 4.409 | 4.409 | 4.409 | 16.2 | 1167–2267 | data |
| (385343) 2002 LV | 2076-08-04 | 4.184 | 4.183 | 4.185 | 16.6 | 1011–3266 | data |
| (52768) 1998 OR2 2079-04-16 4.611 4.611 4.612 15.8 1462–4721 data | |||||||
| (33342) 1998 WT24 | 2099-12-18 | 4.919 | 4.919 | 4.919 | 17.9 | 556–1795 | data |
| (85182) 1991 AQ | 2130-01-27 | 4.140 | 4.139 | 4.141 | 17.1 | 1100 | data |
| 314082 Dryope | 2186-07-16 | 3.709 | 2.996 | 4.786 | 17.5 | 668–2158 | data |
| (137126) 1999 CF9 | 2192-08-21 | 4.970 | 4.967 | 4.973 | 18.0 | 531–1714 | data |
| (290772) 2005 VC | 2198-05-05 | 1.951 | 1.791 | 2.134 | 17.6 | 638–2061 | data |
| (A) List includes near-Earth approaches of less than 5 lunar distances (LD) of objects with H brighter than 18. (B) Nominal geocentric distance from the Earth's center to the object's center (Earth radius≈0.017 LD). (C) Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y. (D) Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD) (E) Color codes: unobserved at close approach observed during close approach upcoming approaches | |||||||
Physical characteristics edit
According to observations by the NASA IRTF telescope during the ExploreNEOs Warm Spitzer program, 1998 OR2 is a rather rare L-type asteroid.[10] Delay-Doppler radar observations by the Arecibo Observatory in April 2020 have shown that 1998 OR2 bears a large, crater-like concavity in its shape.[11] These radar observations have also resolved several other topographic features on the asteroid's surface, such as hills and ridges.[12]
Rotation period edit
In 2009, rotational lightcurves of 1998 OR2 were obtained from photometric observations by astronomers in Salvador, Brazil, and during the Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS). Lightcurve analysis gave a rotation period of 3.198 and 4.112 hours with a brightness amplitude of 0.29 and 0.16 magnitude, respectively (U=2/2+).[13][14] The latter rotation period of 4.1 hours was later confirmed by radar observations of the asteroid in 2020.[12][11]
Diameter and albedo edit
The Collaborative Asteroid Lightcurve Link (CALL) assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 2.15 km (1.34 mi) based on an absolute magnitude of 15.7.[15] It is the first near-earth asteroid to show evidence of shock darkening: the slow darkening of the surface over time, from micrometeorites and solar wind.[5]
Naming edit
As of 2023, this minor planet has not been named.[3]
Notes edit
- ^ 1998 OR2's rotational north pole direction is given in terms of ecliptic coordinates, where λ is ecliptic longitude and β is ecliptic latitude.[1]: 6 β is the angular offset from the ecliptic plane, whereas inclination i with respect to the ecliptic is the angular offset of the asteroid's rotational north pole from the ecliptic north pole at β = +90° ; i with respect to the ecliptic would be the complement of β.[4] Therefore, given β = +20.7° , i = 90° – (+20.7°) = 69.3° from the ecliptic.
References edit
- ^ a b c Devogèle, Maxime; et al. (5 April 2023). (52768) 1998 OR2, an analog to (16) Psyche in the near-Earth space?. 8th IAA Planetary Defense Conference. Vienna, Austria. p. 9. Archived from the original on 5 April 2023.
- ^ a b c d e f g h i j "Small-Body Database Lookup: 52768 (1998 OR2)" (2022-12-26 last obs.). Jet Propulsion Laboratory. Retrieved 5 April 2023.
- ^ a b c d e f g h "52768 (1998 OR2)". Minor Planet Center. Retrieved 7 March 2020.
- ^ "Coordinate transformations". Astronomy and Astrophysics. European Southern Observatory. January 1998. Archived from the original on 17 June 2021. Retrieved 5 April 2023.
- ^ a b c Battle, Adam; Reddy, Vishnu; Sanchez, Juan A.; Sharkey, Benjamin; Pearson, Neil; Bowen, Bryn (September 2022). "Physical Characterization of Near-Earth Asteroid (52768) 1998 OR2: Evidence of Shock Darkening/Impact Melt". The Planetary Science Journal. 3 (9): 13. arXiv:2210.03049. Bibcode:2022PSJ.....3..226B. doi:10.3847/PSJ/ac7223. 226.
- ^ Husárik, Marek; Ivanova, Oleksandra (September 2021). Photometric results of two PHAs: (52768) 1998 OR2 and (99942) Apophis. 16th Europlanet Science Congress 2022. Vol. 16. Granada, Spain: Europlanet Society. Bibcode:2022EPSC...16..671H. doi:10.5194/epsc2022-671. EPSC2022-671.
- ^ a b "List of the Potentially Hazardous Asteroids (PHAs)". Minor Planet Center. Retrieved 24 January 2018.
- ^ 1998OR2 MOID over the next 2700 years – Peter Thomas
- ^ JPL #277 (solution date: 2020-Apr-29) (MaxDist of 0.0420485754979265) – (MinDist of 0.0420484977243086) * 149597870.7 = 12 km
- ^ Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. arXiv:1310.2000. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004. S2CID 119278697.
- ^ a b Virkki, A. K. (23 April 2020). "Arecibo Continues Operations through Pandemic to Observe Potentially Hazardous Asteroid 1998 OR2". Planetary Radar Science Group. NAIC-Arecibo Observatory. Retrieved 23 April 2020.
- ^ a b Kotala, Zenaida Gonzalez (23 April 2020). "Asteroid Visiting Earth's Neighborhood Brings its Own Face Mask". UCF Today. University of Central Florida. Retrieved 23 April 2020.
- ^ Betzler, Alberto Silva; Novaes, Alberto Brum (October 2009). "Photometric Observations of 1998 OR2, 1999 AQ10, and 2008 TC3". The Minor Planet Bulletin. 36 (4): 145–147. Bibcode:2009MPBu...36..145B. ISSN 1052-8091.
- ^ Koehn, Bruce W.; Bowell, Edward G.; Skiff, Brian A.; Sanborn, Jason J.; McLelland, Kyle P.; Pravec, Petr; et al. (October 2014). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2009 January through 2009 June". The Minor Planet Bulletin. 41 (4): 286–300. Bibcode:2014MPBu...41..286K. ISSN 1052-8091.
- ^ "LCDB Data for (52768)". Asteroid Lightcurve Database (LCDB). Retrieved 7 March 2020.
External links edit
- Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
- Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
- (52768) 1998 OR2 at NeoDyS-2, Near Earth Objects—Dynamic Site
- Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
- (52768) 1998 OR2 at ESA–space situational awareness
- Ephemerides · Observations · Orbit · Physical properties · Summary
- (52768) 1998 OR2 at the JPL Small-Body Database