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=== Rotation, light curve, and shape ===
=== Rotation, light curve, and shape ===
Dinkinesh rotates slowly with a [[Rotation period (astronomy)|period]] of {{val|52.67|0.04|u=h}}. As Dinkinesh rotates, its brightness from Earth fluctuates due to its non-spherical shape, which can be inferred from the [[amplitude]] of the asteroid's rotational [[light curve]].<ref name="Mottola2023-06"/><ref name="Mottola2023-09"/> The first [[Photometry (astronomy)|photometric]] observations of Dinkinesh's rotational light curve were attempted with the [[Teide Observatory]]'s 0.8-m IAC-80 telescope at [[Tenerife]], Spain in November 2022, but it did not observe Dinkinesh long enough to make conclusive findings.<ref name="deLeon2023"/>{{rp|page=4}} Longer photometric observations of Dinkinesh were made with the [[Calar Alto Observatory]]'s 1.23-m telescope at [[Almería (province)|Almería]], Spain from November 2022–February 2023, which discovered that Dinkinesh rotates slowly and had a light curve amplitude of {{val|0.39|0.02}} [[magnitude (astronomy)|magnitudes]].<ref name="Mottola2023-06"/><ref name="Mottola2023-09"/>{{rp|page=1}} The observed light curve amplitude of Dinkinesh indicates it has an elongated shape with an [[axial ratio]] of at least 1.43—meaning Dinkinesh's longest equatorial axis is at least 1.43 times longer than its shortest equatorial axis.<ref name="Mottola2023-09"/>{{rp|page=3}} This is in contrast to the similarly-sized asteroids [[101955 Bennu]] and [[162173 Ryugu]], whose shapes are not elongated and resemble [[spinning top]]s due to reshaping by their rapid rotation.<ref name="Mottola2023-09"/>{{rp|page=3}} The origin of Dinkinesh's slow rotation is unknown, but additional clues may be revealed after ''Lucy''{{'}}s flyby of the asteroid.<ref name="Mottola2023-09"/>{{rp|page=4}}
Dinkinesh rotates slowly with a [[Rotation period (astronomy)|period]] of {{val|52.67|0.04|u=h}}. As Dinkinesh rotates, its brightness from Earth fluctuates due to its non-spherical shape, which can be inferred from the [[amplitude]] of the asteroid's rotational [[light curve]].<ref name="Mottola2023-06"/><ref name="Mottola2023-09"/> The first [[Photometry (astronomy)|photometric]] observations of Dinkinesh's rotational light curve were attempted with the [[Teide Observatory]]'s 0.8-m IAC-80 telescope at [[Tenerife]], Spain in November 2022, but it did not observe Dinkinesh long enough to make conclusive findings.<ref name="deLeon2023"/>{{rp|page=4}} Longer photometric observations of Dinkinesh were made with the [[Calar Alto Observatory]]'s 1.23-m telescope at [[Almería (province)|Almería]], Spain from November 2022–February 2023, which discovered that Dinkinesh rotates slowly and had a light curve amplitude of {{val|0.39|0.02}} [[magnitude (astronomy)|magnitudes]].<ref name="Mottola2023-06"/><ref name="Mottola2023-09"/>{{rp|page=1}} The observed light curve amplitude of Dinkinesh indicates it has an elongated shape with an [[axial ratio]] of at least 1.43—meaning Dinkinesh's longest equatorial axis is at least 1.43 times longer than its shortest equatorial axis.<ref name="Mottola2023-09"/>{{rp|page=3}} This is in contrast to the similarly-sized asteroids [[101955 Bennu]] and [[162173 Ryugu]], whose shapes are not elongated and resemble [[spinning top]]s due to reshaping by their rapid rotation.<ref name="Mottola2023-09"/>{{rp|page=3}} The reason for Dinkinesh's slow rotation is unknown.<ref name="Mottola2023-09"/>{{rp|page=4}}


=== Diameter and albedo ===
=== Diameter and albedo ===

Revision as of 03:07, 2 November 2023

152830 Dinkinesh
First images of Dinkinesh (circled) by the Lucy spacecraft in September 2023
Discovery[1]
Discovered byLINEAR
Discovery siteLincoln Lab ETS
Discovery date4 November 1999
Designations
(152830) Dinkinesh
1999 VD57 · 2004 HJ78 · 2007 CB63[2]
main-belt[1] · (inner)
Orbital characteristics[1]
Epoch 25 February 2023 (JD 2460000.5)
Uncertainty parameter 0
Observation arc23.06 yr (8,422 days)
Earliest precovery date15 October 1999
Aphelion2.437 AU
Perihelion1.946 AU
2.191 AU
Eccentricity0.1120
3.24 yr (1,185 d)
25.239°
0° 18m 13.874s / day
Inclination2.094°
21.380°
66.711°
Physical characteristics
Dimensions960 × 670 m[3]: 6 
760+110
−210
 m
[3]
52.67±0.04 h[4][5]
0.27+0.25
−0.06
[3]
Sq[6][7]
V–R = 0.455±0.025[5]
17.62±0.04 (V-band)[6][5]: L3 

152830 Dinkinesh (provisional designation 1999 VD57) is a small, stony main-belt asteroid about 760 meters (2,500 feet) in diameter. It was discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) survey at Socorro, New Mexico on 4 November 1999. This asteroid is the first flyby target of NASA's Lucy mission, which approached 425 km (264 mi) from the asteroid on 1 November 2023.[8] Dinkinesh is the smallest main-belt asteroid explored by spacecraft yet.[9] The asteroid has an elongated shape and rotates slowly with a period of 52.67 hours.[4][5]

Discovery and observational history

Dinkinesh was discovered on 4 November 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey at Socorro, New Mexico.[2] The discovery observations were published by the Minor Planet Center (MPC) on 23 November 1999 and the asteroid was given the minor planet provisional designation 1999 VD57, which describes its discovery year, month, and order.[10] The LINEAR and Spacewatch (Kitt Peak, Arizona) surveys continued observing Dinkinesh until 15 November 1999, after which the asteroid became lost and went unrecognized for years.[2]

On 19 April 2004, Spacewatch reobserved Dinkinesh as a seemingly new asteroid, but misattributed these observations to those of another unrelated asteroid, 2004 GZ43, which was discovered by the same survey on 12 April 2004.[2][11] Dinkinesh was again reobserved as a seemingly new asteroid on 15 and 17 February 2007 by Palomar Observatory's Near-Earth Asteroid Tracking (NEAT) survey at San Diego County, California, which led the MPC to give Dinkinesh the provisional designation 2007 CB63 on 25 February 2007.[2][12] Gareth V. Williams, the associate director of the MPC at time, recognized that 1999 VD57 and 2007 CB63 were the same asteroid and published the linkage on 2 March 2007.[13][14] The linkage between Dinkinesh's 1999 and 2007 observations enabled the MPC to find additional observations from 2001–2007, where the asteroid was previously detected unknowingly.[15][16] The linkage and additional observations extended Dinkinesh's observation arc to over 7 years and greatly reduced uncertainties in its orbit, which permitted the MPC to give Dinkinesh its permanent minor planet catalog number 152830 on 2 April 2007.[17][14] Pre-discovery LINEAR observations of Dinkinesh from 15 October 1999 were later identified and published on 19 August 2007.[18]

On 3 March 2007, the MPC established that Spacewatch's 2004 observations of Dinkinesh were not of 2004 GZ43, and thus redesignated these observations as 2004 HJ78.[19] However, the MPC did not recognize that 2004 HJ78 was Dinkinesh until Gareth Williams made the linkage and published it on 9 February 2009.[20]

Name

Dinkinesh is the Ethiopian name for the Lucy fossil, after which NASA's Lucy mission is named.[21] The name means "you are wonderful" in the Amharic language (ድንቅነሽ).[22][23] "Din(i)k'i" means "wonderful"[24] and "nesh" means "you are" in feminine form of this pronoun and verb.[25] The asteroid was unnamed when it was selected for exploration by the Lucy spacecraft, so the Lucy mission team proposed the name Dinkinesh to the International Astronomical Union's Working Group for Small Bodies Nomenclature, which approved and announced the name on 6 February 2023.[21][22]

Orbit

Dinkinesh orbits the Sun in the inner main asteroid belt on an elliptical orbit with an average distance of 2.19 astronomical units (328 million km, 204 million mi) and an orbital period of 3.24 years.[1] With an orbital eccentricity of 0.112, Dinkinesh comes as close as 1.95 AU (292 million km; 181 million mi) from the Sun at perihelion to as far as 2.44 AU (365 million km; 227 million mi) at aphelion.[1] The asteroid's orbit is inclined 2.1° with respect to the plane of the Solar System.[1] Dinkinesh is possibly a member of the Flora family, a group of asteroids that share similar orbital characteristics as the family's parent asteroid 8 Flora.[3]: 5 

Exploration

Orbit diagram of Lucy's flyby of Dinkinesh (1999 VD57) on 1 November 2023

The Lucy spacecraft made a flyby of Dinkinesh from a distance of 425 km (264 mi) on 1 November 2023 16:54 UTC.[8][26] Lucy's flyby of Dinkinesh was announced by NASA and the Lucy science team on 25 January 2023, more than one year after Lucy had launched in October 2021.[9] The asteroid was initially overlooked as a potential flyby target because it was too small.[9] It was identified in August 2022 by Raphael Marschall, mission collaborator of the Nice Observatory, after he investigated 500,000 asteroids for potential close approaches with the spacecraft.[9][27] The original trajectory of Lucy took it within 64,000 km (40,000 mi) of Dinkinesh, but a series of planned trajectory correction maneuvers from May to September 2023 allowed Lucy to approach much closer.[9][28][29]

Dinkinesh was Lucy's first and smallest asteroid flyby during its mission, and is the smallest main-belt asteroid explored by spacecraft yet.[9] The Dinkinesh flyby served to test Lucy's autonomous tracking capabilities before it will apply them to its main science targets, the Jupiter trojans.[9][30] Lucy took its first images of Dinkinesh on 3–5 September 2023, when the asteroid was 23 million km (14 million mi) away from the spacecraft.[8] The spacecraft continued imaging Dinkinesh from afar to aid its optical navigation over the coming days before the flyby.[8] Because Dinkinesh is very small, Lucy did not resolve surface detail on Dinkinesh until the day of the flyby.[8] At closest approach, Lucy was moving 4.5 km/s (2.8 mi/s) relative to Dinkinesh and it is expected to take 2 meters/pixel resolution images of the asteroid with the panchromatic L'LORRI imager, 15 m/pixel color images with the L'Ralph imager, and 24 m/pixel near-infrared spectra and thermal measurements with the L'TES spectrometer.[8][30]

Physical characteristics

Surface and spectrum

Visible light spectrum of Dinkinesh (gray) compared to the spectra of S-, Sq-, and Sv-type asteroids (red, orange, and yellow, respectively)

Visible light spectroscopy of Dinkinesh by two independent teams of researchers in November–December 2022 showed that it is an S-type asteroid, meaning it is mainly composed of rocky silicates and small amounts of metal.[7]: 1 [6] Spectral data obtained from the 10-meter Keck I telescope at Mauna Kea, Hawaii indicates that Dinkinesh belongs to the Sq subclass of S-type asteroids because it exhibits the 1 μm olivine and pyroxene spectral absorption band that is characteristically seen in Q-type asteroids.[6][31]: 4, 6  On the other hand, spectral data from the 8.1-meter Gemini South telescope at Cerro Pachón, Chile showed that Dinkinesh's spectrum more closely resembles a standard S-type asteroid with a shallower 1 μm band.[6] This difference between the two measured spectra of Dinkinesh may be caused by either observational artifacts or compositional variations across Dinkinesh's surface as it rotates.[6] If the latter possibility is true, then Dinkinesh's varying 1 μm band would indicate that there is space-weathered material that is unevenly distributed across its surface, likely due to impacts and surface topography.[6]

Rotation, light curve, and shape

Dinkinesh rotates slowly with a period of 52.67±0.04 h. As Dinkinesh rotates, its brightness from Earth fluctuates due to its non-spherical shape, which can be inferred from the amplitude of the asteroid's rotational light curve.[4][5] The first photometric observations of Dinkinesh's rotational light curve were attempted with the Teide Observatory's 0.8-m IAC-80 telescope at Tenerife, Spain in November 2022, but it did not observe Dinkinesh long enough to make conclusive findings.[7]: 4  Longer photometric observations of Dinkinesh were made with the Calar Alto Observatory's 1.23-m telescope at Almería, Spain from November 2022–February 2023, which discovered that Dinkinesh rotates slowly and had a light curve amplitude of 0.39±0.02 magnitudes.[4][5]: 1  The observed light curve amplitude of Dinkinesh indicates it has an elongated shape with an axial ratio of at least 1.43—meaning Dinkinesh's longest equatorial axis is at least 1.43 times longer than its shortest equatorial axis.[5]: 3  This is in contrast to the similarly-sized asteroids 101955 Bennu and 162173 Ryugu, whose shapes are not elongated and resemble spinning tops due to reshaping by their rapid rotation.[5]: 3  The reason for Dinkinesh's slow rotation is unknown.[5]: 4 

Diameter and albedo

Dinkinesh has an average diameter of 760 m (2,490 ft) according to infrared thermal emission measurements made by the Wide-field Infrared Survey Explorer (WISE) in March 2010.[3]: 5  Since Dinkinesh is elongated according to light curve measurements, the dimensions of Dinkinesh are 960 m × 670 m (3,150 ft × 2,200 ft) for its longest and shortest axes, respectively.[3]: 6  Given Dinkinesh's diameter and absolute magnitude, the geometric albedo of its surface is 0.27, which is consistent with those of S-type asteroids.[3]

See also

References

  1. ^ a b c d e f "JPL Small-Body Database Browser: 152830 (1999 VD57)" (2022-11-05 last obs.). Jet Propulsion Laboratory. Retrieved 25 January 2023.
  2. ^ a b c d e "(152830) = 2004 HJ78 = 1999 VD57 = 2007 CB63". Minor Planet Center. Retrieved 25 January 2023.
  3. ^ a b c d e f g McFadden, Kiana D.; Mainzer, Amy K.; Masiero, Joseph R.; Bauer, James M.; Cutri, Roc M.; Dahlen, Dar; et al. (November 2023). "Size and Albedo Constraints for (152830) Dinkinesh Using WISE Data". Astrophysical Journal Letters. 957 (1): 6. arXiv:2309.13158. Bibcode:2023ApJ...957L...2M. doi:10.3847/2041-8213/acff61. L2.
  4. ^ a b c d Mottola, S.; Denk, T.; Marchi, S.; Binzel, R. P.; Noll, K. S.; Spencer, J. R.; Levison, H. F. (June 2023). Pre-Encounter Characterization of the Lucy Target (152830) Dinkinesh (PDF). Asteroids, Comets, Meteors Conference 2023. Lunar and Planetary Institute. 2486.
  5. ^ a b c d e f g h i Mottola, Stephano; Denk, Tilmann; Marchi, Simone; Binzel, Richard P.; Noll, Keith S.; Spencer, John R.; Levison, Harold F. (September 2023). "Characterizing asteroid (152830) Dinkinesh in preparation for the encounter with the NASA Lucy mission: a photometric study". Monthly Notices of the Royal Astronomical Society: Letters. 524 (1): L1–L4. Bibcode:2023MNRAS.524L...1M. doi:10.1093/mnrasl/slad066.
  6. ^ a b c d e f g Bolin, B. T.; Noll, K. S.; Caiazzo, I.; Fremling, C.; Binzel, R. P. (August 2023). "Keck and Gemini spectral characterization of Lucy mission fly-by target (152830) Dinkinesh". Icarus. 400. arXiv:2303.08130. Bibcode:2023Icar..40015562B. doi:10.1016/j.icarus.2023.115562. S2CID 257505087. 115562.
  7. ^ a b c de León, J.; Licandro, J.; Pinilla-Alonso, N.; Moskovitz, N.; Kareta, T.; Popescu, M.; et al. (April 2023). "Characterisation of the new target of the NASA Lucy mission: asteroid 152830 Dinkinesh (1999 VD57)". Astronomy & Astrophysics. 672: 4. arXiv:2303.05918. Bibcode:2023A&A...672A.174D. doi:10.1051/0004-6361/202346278. A174.
  8. ^ a b c d e f Kretke, Katherine (11 September 2023). "NASA's Lucy Spacecraft Captures its 1st Images of Asteroid Dinkinesh". NASA. Retrieved 12 September 2023.
  9. ^ a b c d e f g Evans, Jessica (25 January 2023). "NASA's Lucy Team Announces New Asteroid Target". NASA. Retrieved 25 January 2023.
  10. ^ "M. P. S. 7496" (PDF). Minor Planet Circulars Supplement. Minor Planet Center. 23 November 1999. p. 284. Archived (PDF) from the original on 13 September 2023. Retrieved 13 September 2023.
  11. ^ "M. P. S. 105236" (PDF). Minor Planet Circulars Supplement. Minor Planet Center. 25 April 2004. p. 414. Archived (PDF) from the original on 28 August 2017. Retrieved 13 September 2023.
  12. ^ "M. P. S. 200485" (PDF). Minor Planet Circulars Supplement. Minor Planet Center. 25 February 2007. p. 253. Archived (PDF) from the original on 4 October 2017. Retrieved 13 September 2023.
  13. ^ "MPEC 2007-E01 : DAILY ORBIT UPDATE (2007 MAR. 2 UT)". Minor Planet Electronic Circulars. Minor Planet Center. 2 March 2007. Retrieved 13 September 2023.
  14. ^ a b "M. P. O. 116514" (PDF). Minor Planet Circulars Orbit Supplement. Minor Planet Center. 2 April 2007. p. 96. Archived (PDF) from the original on 14 September 2016. Retrieved 13 September 2023.
  15. ^ "M. P. S. 201406" (PDF). Minor Planet Circulars Supplement. Minor Planet Center. 3 March 2007. p. 10. Archived (PDF) from the original on 4 October 2017. Retrieved 13 September 2023.
  16. ^ "M. P. O. 115681" (PDF). Minor Planet Circulars Orbit Supplement. Minor Planet Center. 3 March 2007. p. 839. Archived (PDF) from the original on 14 September 2016. Retrieved 13 September 2023.
  17. ^ "M. P. C. 59323" (PDF). Minor Planet Circulars. Minor Planet Center. 2 April 2007. p. 47. Archived (PDF) from the original on 14 August 2016. Retrieved 13 September 2023.
  18. ^ "M. P. O. 213622" (PDF). Minor Planet Circulars Supplement. Minor Planet Center. 19 August 2007. p. 620. Archived (PDF) from the original on 14 September 2016. Retrieved 13 September 2023.
  19. ^ "M. P. C. 58994" (PDF). Minor Planet Circulars. Minor Planet Center. 3 March 2007. p. 4. Archived (PDF) from the original on 28 August 2017. Retrieved 13 September 2023.
  20. ^ "M. P. C. 64979" (PDF). Minor Planet Circulars. Minor Planet Center. 9 February 2007. p. 9. Archived (PDF) from the original on 28 August 2017. Retrieved 13 September 2023.
  21. ^ a b Foust, Jeff (26 January 2023). "NASA adds asteroid flyby to Lucy mission". SpaceNews. Retrieved 26 January 2023.
  22. ^ a b "WGSBN Bulletin 3, #2" (PDF). WGSBN Bulletin. 3 (2). International Astronomical Union: 22. 6 February 2023. Retrieved 6 February 2023.
  23. ^ Kretke, Katherine (1 March 2023). "Introducing "Dinkinesh" – First Asteroid Target for NASA's Lucy Mission Gets a Name". SciTechDaily. Retrieved 2 March 2023.
  24. ^ How to Say Wonderful in Amharic
  25. ^ Helpful Amharic Words & Phrases
  26. ^ Kretke, Katherine (19 October 2023). "NASA's Lucy Spacecraft Preparing for its First Asteroid Flyby". NASA. Retrieved 21 October 2023.
  27. ^ Spencer, J.; Levison, H.; Marchi, S.; Noll, K.; Salmon, J.; Marschall, R.; et al. (October 2023). The Lucy Encounter with (152830) Dinkinesh. 55th Annual DPS Meeting Joint with EPSC. Vol. 55. San Antonio, Texas. 102.06.
  28. ^ Morton, Erin (18 May 2023). "NASA's Lucy Spacecraft Adjusts Course for Asteroid Flyby in November". NASA Blogs. NASA. Retrieved 21 October 2023.
  29. ^ Kretke, Katherine (13 October 2023). "NASA's Lucy Spacecraft Continues Approach to Asteroid Dinkinesh". NASA. Retrieved 21 October 2023.
  30. ^ a b Spencer, J. R.; Levison, H. A.; Marchi, S.; Salmon, J. J..; Noll, K. S.; Solanki, I.; Olkin, C. A. (June 2023). Planning Close Encounter Science Observations for the Lucy Mission (PDF). Asteroids, Comets, Meteors Conference 2023. Lunar and Planetary Institute. 2456.
  31. ^ Palamakumbure, Lakshika; Mizohata, Kenichiro; Flanderová, Kateřina; Korda, David; Penttilä, Antti; Kouhout, Tomáš (April 2023). "Simulation of Space Weathering on Asteroid Spectra through Hydrogen Ion Irradiation of Meteorites". The Planetary Science Journal. 4 (4): 10. Bibcode:2023PSJ.....4...72P. doi:10.3847/PSJ/acc848. 72.