 | |
| Discovery[1][2] | |
|---|---|
| Discovered by | OAM |
| Discovery site | La Sagra Obs. |
| Discovery date | 23 February 2012 |
| Designations | |
| (367943) Duende | |
Named after | Duende (Iberian/Filipino mythology)[1] |
| 2012 DA14 | |
| Orbital characteristics[3] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 364 days |
| Aphelion | 0.9916 AU |
| Perihelion | 0.8289 AU |
| 0.9103 AU | |
| Eccentricity | 0.0894 |
| 0.87 yr (317 days) | |
| 113.74° | |
| 1° 8m 5.64s / day | |
| Inclination | 11.609° |
| 146.96° | |
| 195.60° | |
| Earth MOID | 9.52648×10−5 AU (0.037 LD) |
| Physical characteristics | |
| Dimensions | 20 m × 40 m(elongated)[5][6] |
| 7.2(2013 peak)[14] | |
367943 Duende (provisional designation2012 DA14) is a micro-asteroid and anear-Earth object of theAten andAtira group, approximately 30 meters (98 ft) in diameter. It was discovered by astronomers of theAstronomical Observatory of Mallorca at its roboticLa Sagra Observatory in 2012, and named for theduende, a goblin-like creature from Iberian mythology and folklore.[1]Duende is likely an uncommonL-type asteroid and significantly elongated. For an asteroid of its size, it has a relatively longrotation period of 9.485 hours.[9]
On 15 February 2013, Duende passed at arecord distance of 27,700 km (17,200 mi) or 4.3Earth radii from Earth's surface.[4] Due to its close passage, its orbit wasperturbed significantly enough that it changed from anApollo asteroid to anAten asteroid. Duende's passage alsocoincided with the completely unrelatedChelyabinsk meteor, which entered Earth's atmosphere above Russia just 16 hours earlier.[15][16][17]
Duende was discovered on 23 February 2012, seven days after passing 0.0174 AU (2,600,000 km; 1,620,000 mi) from Earth,[18] by theLa Sagra Observatory inGranada Province,Spain,[2] using a 0.45-mreflector which was remotely operated byamateur astronomers at theAstronomical Observatory of Mallorca.[19]
The still relatively imprecise orbit deduced from the short arc of the 2012 observations already made clear that Duende would pass no closer to Earth's surface than 3.2Earth radii during its 2013 passage.[20] There was at the time, however, a cumulative risk of 0.033% (1 in 3,030) that Duende would impact Earth during one of its 2026 to 2069 approaches.[8]
On 9 January 2013, Duende was observed again byLas Campanas Observatory and the observation arc immediately increased from 79 days to 321 days.[1] On 15 February 2013 at 19:25UT, Duende passed 0.0002276 AU (34,050 km; 21,160 mi) from the center of Earth, with an uncertainty region of about 0.0000001 AU (15 km; 9.3 mi).[18]
It passed 27,743 kilometers (17,239 mi) above Earth's surface, closer than satellites ingeosynchronous orbit. It briefly peaked at anapparent magnitude of roughly 7.2, a factor of a few fainter than would have been visible to thenaked eye. The best observation location for the closest approach was Indonesia. Eastern Europe, Asia, and Australia also were well situated to observe Duende during its closest approach.[4]
Duende was not expected to pass any closer than 1950 km to any satellites.[21]Goldstone Observatory observed Duende withradar from February 16 to February 20.[5][22] Radar observations showed that it is an elongated asteroid with dimensions of 20 by 40 meters (66 by 131 feet).[23] This gives Duende ageometric mean (spherical) diameter equivalent to 28 meters (92 ft).
During the close approach, an observational campaign involving 5 different telescopes in 4 different observatories was carried on in order to get information on the physical properties of this NEO.[7]
Visible and near-Infrared photometry and visible spectroscopy were obtained atGran Telescopio Canarias,Telescopio Nazionale Galileo andCalar Alto Observatory and put together. The classification using the M4AST online tool says this is an L-type asteroid. Those peculiar asteroids are characterized by a strongly reddish spectrum shortward of 0.8 μm, and a featureless flat spectrum longward of this, with little or no concave-up curvature related to a 1 μm silicon absorption band.Time-series photometry was also obtained in the Observatorio de La Hita (I95)[2] andObservatorio de Sierra Nevada[citation needed] during two consecutive nights (15–16 February 2013). All of this data were co-phased to build alightcurve of the object. This lightcurve is double-peak and presents large variations in magnitude, implying a very elongated object, which is compatible with radar observations.[5] The amplitude of the lightcurve yields an axial ratio that, together with the long axis of 40 m inferred from the radar images byGoldstone, results in an equivalent diameter of 18 m, much smaller than the estimations before the close-approach.
Therotational period was precisely determined from the lightcurve obtaining a value of8.95±0.08 h.[7] This value is confirmed with an analysis of all the photometry of this objects reported to theMinor Planet Center. Using data pre and post close approach the authors find that the object suffered a spin-up during the event that decreased the rotational period from9.8±0.1 down to8.8±0.1 hours, which is compatible with the more accurate value estimated from the light-curve.[9]
The close approach to Earth reduced the orbital period of Duende from 368 days to 317 days, Its aphelion was reduced from 1.110 to 0.9917 AU, leaving it almost entirely inside Earth's orbit andperturbing it from theApollo class to theAten class of near-Earth asteroids.[4][24]
Its next close approach to Earth will be on 15 February 2046, when it will pass about 0.0148 AU (2,210,000 km; 1,380,000 mi) from Earth. Based on 7 radar observations, the next close approach to Earth similar to the 2013 passage will be on 16 February 2123, when Duende will pass no closer than 0.0002 AU (30,000 km; 19,000 mi) from the center of Earth. For the 2123 passage, thenominal pass will be 0.003 AU (450,000 km; 280,000 mi) from the center of the Moon and then 0.005 AU (750,000 km; 460,000 mi) from the center of Earth.[18]
| Parameter | Epoch | Aphelion (Q) | Perihelion (q) | Semi-major axis (a) | Eccentricity (e) | Period (p) | Inclination (i) | Longitude ascending node (Ω) | Mean anomaly (M) | Argument of perihelion (ω) |
|---|---|---|---|---|---|---|---|---|---|---|
| Units | AU | (days) | (°) | |||||||
| Pre-flyby | 30 Sep 2012 | 1.110 | 0.8935 | 1.001 | 0.1081 | 366.2 | 10.33° | 147.2° | 299.9° | 271.0° |
| Post-flyby | 18 Apr 2013 | 0.9917 | 0.8289 | 0.9103 | 0.0894 | 317.2 | 11.60° | 146.9° | 231.0° | 195.5° |
Risk assessments calculated before the 2013 passage were based on a diameter of 45 meters and a mass of 130,000tonnes.[8] It was estimated that, if it were ever to impact Earth, it would enter the atmosphere at a speed of 12.7 km/s, would have akinetic energy equivalent to 2.4megatons of TNT,[8] and would produce anair burst with the equivalent of 2.1 megatons of TNT[25] at an altitude of roughly 10.1 kilometers (33,000 ft).[25] TheTunguska event has been estimated at 3–20 megatons.[26] Asteroids of approximately 50 meters in diameter are expected to impact Earth once every 1,200 years or so.[27] Asteroids larger than 35 meters across can pose a threat to a town or city,[28] and theChelyabinsk meteor which serendipitously occurred on the day of the 2013 passage was due to a 17-meter asteroid. As a result of radar observations, it is now known that Duende is only about 30 meters in diameter.[5]
| Diameter | Kinetic energy at atmospheric entry | Airburst energy | Airburst altitude | Average frequency |
|---|---|---|---|---|
| 30 m (98 ft) | 708kt | 530 kt | 16.1 km (53,000 ft) | 185 years |
| 50 m (160 ft) | 3.3Mt | 2.9 Mt | 8.5 km (28,000 ft) | 764 years |
| 70 m (230 ft) | 9 Mt | 8.5 Mt | 3.4 km (11,000 ft) | 1900 years |
| 85 m (279 ft) | 16.1 Mt | 15.6 Mt | 0.435 km (1,430 ft) | 3300 years |
The table above usesSentry's stony asteroid density of 2600 kg/m3, Sentry's atmospheric entry velocity (Vimpact) of 12.7 km/s,[8] and an angle of 45 degrees.
For kinetic energy at atmospheric entry, 3.3 Mt is equivalent toDF-4, 9 Mt is equivalent toIvy Mike and 15.6 Mt is equivalent toCastle Bravo. Forair burst energy, 530 kt is equivalent toW88 and 2.9 Mt is equivalent toR-12 Dvina.[citation needed]
Thisminor planet was named after theduende,fairy- orgoblin-like mythological creatures fromIberian, Latin American andFilipino folklore.[1] The approved naming citation was published by theMinor Planet Center on 17 November 2013(M.P.C. 85916).[31]
| Preceded by | LargeNEO Earth close approach (inside the orbit of the Moon) 15 February 2013 | Succeeded by |
2013 in space | ||||||
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Space probe launches |
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| SelectedNEOs | ||||||
| Exoplanets | ||||||
| Discoveries | ||||||
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| Space exploration |
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