54509 YORP
 Radar image and 3D model of YORP | |
| Discovery[1] | |
|---|---|
| Discovered by | LINEAR |
| Discovery site | Lincoln Lab's ETS |
| Discovery date | 3 August 2000 |
| Designations | |
| (54509) YORP | |
Named after | YORP effect |
| 2000 PH5 | |
Apollo  NEO | |
| Orbital characteristics[2][3] | |
| Epoch 21 November 2025 (JD 2461000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 1826 days (5.00 yr) |
| Aphelion | 1.23717 AU (185.078 Gm) |
| Perihelion | 0.77455 AU (115.871 Gm) |
| 1.00586 AU (150.475 Gm) | |
| Eccentricity | 0.22996 |
| 1.01 yr (368.47 d) | |
Average orbital speed | 29.31 km/s |
| 130.15693° | |
| 0° 58m 37.245s / day | |
| Inclination | 1.59946° |
| 278.18528° | |
| 278.99884° | |
| Earth MOID | 0.000495246 AU (74,087.7 km) |
| Jupiter MOID | 3.72092 AU (556.642 Gm) |
| TJupiter | 6.029 |
| Physical characteristics | |
| Dimensions | 150×128×93 m[4] |
| 0.2029 h 12.174 min[3] | |
| 173°[4] | |
Pole ecliptic longitude | 180°[4] |
Pole ecliptic latitude | −85°[4] |
| 22.7 (JPL)[3] | |
54509 YORP (provisional designation 2000 PH5) is an Earth co-orbital asteroid[5] discovered on 3 August 2000 by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) Team at Lincoln Laboratory Experimental Test Site in Socorro, New Mexico. Measurements of the rotation rate of this object provided the first observational evidence of the YORP effect, hence the name of the asteroid. The asteroid's rate of rotation is increasing at the rate of (2.0 ± 0.2) × 10−4 deg/day2 which between 2001 and 2005 caused the asteroid to rotate about 250° further than its spin rate in 2001 would have predicted.[4] Simulations of the asteroid suggest that it may reach a rotation period of ~20 seconds near the end of its expected lifetime, which has a 75% probability of happening within the next 35 million years.[6] The simulations also ruled out the possibility that close encounters with the Earth have been the cause of the increased spin rate.[6]
Discovery and naming
[edit]YORP was discovered on 3 August 2000 by the Lincoln Near-Earth Asteroid Research (LINEAR) program at the Lincoln Laboratory's Experimental Test Site in Socorro, New Mexico. It was given the provisional designation 2000 PH5,[1] and its discovery was announced in a Minor Planets Electronic Circular on 7 August.[7] At the time of discovery, YORP was located 0.04 astronomical units (AU) away from Earth.[4]: 275 Once its orbit was sufficiently determined, it was numbered 54509 by the Minor Planet Center on 16 February 2003.[8]: 905 It is named after researchers Ivan Yarkovsky, John O'Keefe, Vladimir Radzievskij, and Stephen Paddock, contributors to the understanding of the mechanisms behind the YORP effect and after whom the effect is named. The naming was chosen as the asteroid provided the first direct observational evidence for the effect; the name announced in Minor Planets Circular 59387 on 2 April 2007.[9]
Orbit
[edit]YORP orbits the Sun with an average distance, or semi-major axis, of 1.006 AU, completing one orbit in 368.5 days. Due to its orbital eccentricity of 0.23, its distance from the Sun varies from 0.775 AU at perihelion to 1.237 AU at aphelion, crossing Earth's orbit. YORP's orbit is inclined by 1.6° with respect to the ecliptic plane.[3]
YORP is classified as an Apollo asteroid,[3] a subgroup of Earth-crossing near-Earth asteroids (NEAs) with semi-major axes greater than 1 AU.[10] YORP is also classified as an Earth co-orbital; it is in a near-1:1 mean-motion resonance with Earth in a horseshoe configuration.[6]: 273 In a horseshoe configuration, the asteroid's orbit librates between the L4 and L5 Lagrange points, traversing the L3 point.[11]: 1 Over a cycle lasting about 100 years, YORP librates until it experiences a close encounter with Earth, after which its libration reverses direction until it encounters Earth again. Because of its eccentricity, its encounters with Earth are close, coming within a few lunar distances. For the past cycle, YORP trailed Earth, approaching it at a rate of roughly 3° per year. It encountered Earth in July 2003, where its semi-major axis was raised from 0.994 AU to 1.006 AU. It is currently lagging behind by 3° per year; it will reach the other end of its horseshoe path about 100 years from now.[12]
Possible asteroid group
[edit]YORP is the largest member of a candidate asteroid group. More than a dozen NEAs have similar orbital properties to YORP, including 2017 DR109, which also follows a horseshoe trajectory.[13]: 3451 A 2018 study by Carlos and Raul de la Fuente Marcos concluded that the asteroids are likely dynamically if not genetically related,[13]: 3445 but the scarcity of spectroscopic data and the poorly determined orbits of several candidate members prevented a definitive confirmation. Several of these asteroids may originate from YORP effect-driven mass shedding of 54509 YORP, tidal disruption events from close Earth and Venus encounters, and collisional disruption.[13]: 3450–3451
| Asteroid | a (AU) | e | i (°) | Earth MOID (AU) | H (mag) |
|---|---|---|---|---|---|
| 54509 YORP | 1.0062 | 0.2302 | 1.5993 | 0.0028 | 22.7 |
| 2009 HE60 | 0.9958 | 0.2649 | 1.5848 | 0.0154 | 25.6 |
| 2012 VZ19 | 0.9825 | 0.2541 | 1.2474 | 0.0111 | 25.6 |
| (488490) 2000 AF20 | 1.0341 | 0.2768 | 2.4084 | 0.0182 | 21.7 |
| 2017 BU | 1.0196 | 0.2512 | 1.5052 | 0.0229 | 25.1 |
| 2015 YA | 0.9962 | 0.2794 | 1.6192 | 0.0035 | 27.4 |
| 2008 UB95 | 0.9897 | 0.2686 | 3.2372 | 0.0003 | 24.7 |
| 2016 JA | 0.0132 | 0.2685 | 0.0579 | 0.0002 | 27.6 |
| 2017 DR109 | 1.0006 | 0.2414 | 3.0600 | 0.0062 | 27.6 |
| 2012 BD14 | 1.0176 | 0.2405 | 1.5356 | 0.0080 | 26.5 |
| 2000 QX69 | 1.0101 | 0.2715 | 4.5740 | 0.0002 | 24.2 |
| 2014 NZ64 | 1.0368 | 0.2734 | 4.4945 | 0.0092 | 22.8 |
| 2010 FN | 0.9896 | 0.2110 | 0.1237 | 0.0008 | 26.6 |
| 2002 VX91 | 0.9840 | 0.2013 | 2.3417 | 0.0018 | 24.3 |
| (471984) 2013 UE3 | 1.0262 | 0.2257 | 3.3574 | 0.0235 | 22.7 |
| 2007 WU3 | 1.0113 | 0.2040 | 2.3933 | 0.0402 | 23.8 |
| 2009 BK2 | 1.0125 | 0.2126 | 3.5534 | 0.0260 | 25.3 |
| 2011 OJ45 | 1.0169 | 0.2037 | 0.7492 | 0.0076 | 26.0 |
| 2017 FZ2 | 1.0071 | 0.2641 | 1.8117 | 0.0014 | 26.7 |
Physical characteristics
[edit]YORP's size and shape has been directly measured through radar observations conducted by the Goldstone observatory on 27–28 July 2001 and the Arecibo Telescope on 27–28 July 2004 and 24–26 July 2005.[4]: 275 Various shape models were compared against Doppler images of YORP, with the best-fit model having a diameter of 112.8 metres (370 ft) and dimensions of 149 by 134 by 96 metres (489 ft × 440 ft × 315 ft).[4]: 276 YORP has a very irregular shape, with Doppler imagery revealing convex, linear, and concave topography features. Its northern hemisphere is flattened, though it has a prominent concavity.[4]: 275–276
Rotation
[edit]YORP has a retrograde spin, with an axial tilt of 173° relative to its orbit normal. Its spin axis points towards the ecliptic south, lying within 10° of the J2000 ecliptic coordinates (180°, –85°). Observations of YORP's lightcurve, or fluctuations in brightness as it rotates, suggests a sidereal rotation period of 12.17 minutes, which has been corroborated by radar observations.[4]: 275–276 YORP's fast rotation and small size classifies it as a monolithic fast rotator.[6]: 273
In 2007, two studies—one led by Stephen C. Lowry and the other led by Patrick A. Taylor—investigated changes in YORP's rotation period over time, reporting the direct detection of the YORP effect.[6]: 272 [4]: 274 This was the first direct observational evidence of the YORP effect;[9] previously, evidence of the effect was indirect, manifesting in the anomalous distributions of some asteroids' rotation periods and axial tilts.[6]: 272 YORP's lightcurve data from 2001 to 2005 suggests its rotation period is fractionally decreasing by 1.7×10−6 per year.[6]: 274 Taylor and collaborators used YORP's shape model to theoretically derive the expected change in its rotation period under the YORP effect. Despite incomplete shape and thermal data, theoretical predictions agreed within an order of magnitude with the observed change in period. Tidal torques from repeated close encounters with Earth were ruled out as an explanation, leaving the YORP effect as the most likely explanation for the change in the asteroid's spin.[4]: 276
Gallery
[edit]
See also
[edit]Notes
[edit]References
[edit]- ^ a b "(54509) YORP = 2000 PH5". Minor Planet Center. Archived from the original on 19 February 2025. Retrieved 17 October 2025. (2393 obs)
- ^ "The Asteroid Orbital Elements Database". astorb. Lowell Observatory. Archived from the original on 14 August 2001. Retrieved 19 October 2025.
- ^ a b c d e "54509 YORP". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 54509. Retrieved 12 April 2016.
- ^ a b c d e f g h i j k l Taylor, Patrick A.; et al. (13 April 2007). "Spin Rate of Asteroid (54509) 2000 PH5 Increasing Due to the YORP Effect" (PDF). Science. 316 (5822): 274–277. Bibcode:2007Sci...316..274T. doi:10.1126/science.1139038. PMID 17347415. S2CID 29191700. Archived (PDF) from the original on 23 September 2015. Retrieved 19 October 2025.
- ^ Brasser, R; Innanen, K. A; Connors, M; Veillet, C; Wiegert, P; Mikkola, Seppo; Chodas, P. W (1 September 2004). "Transient co-orbital asteroids". Icarus. 171 (1): 102–109. Bibcode:2004Icar..171..102B. doi:10.1016/j.icarus.2004.04.019. ISSN 0019-1035. Archived from the original on 30 July 2025. Retrieved 19 October 2025.
- ^ a b c d e f g Lowry, Stephen C.; et al. (13 April 2007). "Direct Detection of the Asteroidal YORP Effect" (PDF). Science. 316 (5822): 272–274. Bibcode:2007Sci...316..272L. doi:10.1126/science.1139040. PMID 17347414. S2CID 26687221. Archived from the original (PDF) on 24 July 2011.
- ^ Minor Planet Center Staff (7 August 2000). "MPEC 2000-P32 : 2000 PH5". Minor Planet Electronic Circular. 2000-P32. Minor Planet Center. Bibcode:2000MPEC....P...32G. Archived from the original on 12 August 2024. Retrieved 17 October 2025.
- ^ "M. P. O. 38539" (PDF). Minor Planets and Comets Orbit Supplement. Minor Planets Center. 16 February 2003. Archived (PDF) from the original on 19 July 2025. Retrieved 18 October 2025.
- ^ a b "M. P. C. 59387" (PDF). Minor Planet Circulars. Minor Planet Center. 2 April 2007. p. 11. Archived (PDF) from the original on 19 January 2025. Retrieved 18 October 2025.
- ^ "Near-Earth Object Groups". JPL – NASA. Archived from the original on 2 February 2002. Retrieved 11 November 2016.
- ^ Dermott, S. F.; Murray, C. D. (October 1981). "The Dynamics of Tadpole and Horseshoe Orbits I. Theory". Icarus. 48 (1): 1–11. Bibcode:1981Icar...48....1D. doi:10.1016/0019-1035(81)90147-0.
- ^ Margot, Jean-Luc. "2000 PH5". Archived from the original on 6 June 2016. Retrieved 18 October 2025.
- ^ a b c d de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (21 January 2018). "Asteroid 2017 FZ2 et al.: signs of recent mass-shedding from YORP?". Monthly Notices of the Royal Astronomical Society. 473 (3): 3434–3453. arXiv:1709.09379. Bibcode:2018MNRAS.473.3434D. doi:10.1093/mnras/stx2540.
Further reading
[edit]- Mueller, Michael (2007). "Surface Properties of Asteroids from Mid-Infrared Observations and Thermophysical Modeling". Doctoral Dissertation.
External links
[edit]- 54509 YORP at NeoDyS-2, Near Earth Objects—Dynamic Site
- 54509 YORP at ESA–space situational awareness
- 54509 YORP at the JPL Small-Body Database
