(153591) 2001 SN263
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Template:Mp is a carbonaceous triple[1] asteroid, classified as near-Earth object and former potentially hazardous asteroid of the Amor group, approximately Script error: No such module "convert". in diameter. It was discovered by the Lincoln Near-Earth Asteroid Research project at Lincoln Lab's Experimental Test Site in Socorro, New Mexico, on 20 September 2001.[2] The two synchronous minor-planet moons measure approximately 770 and 430 meters and have an orbital period of 16.46 and 150 hours, respectively.[3][4]
Numbering and naming
This minor planet was numbered by the Minor Planet Center on 2 April 2007.[5] As of 2018, the primary and its moons have not been named.[2] In the scientific literature, the components of the triple system are generically referred to as Alpha, Beta and Gamma, but these labels are not recognized by the IAU.[6][3]
Primary
Template:Mp, the primary object of this triple system, is an unusual carbonaceous near-Earth asteroid of a C- or somewhat brighter B-type.[7]Template:Efn It orbits the Sun at a distance of 1.0–2.9 AU once every 2 years and 10 months (1,023 days). Its orbit has an eccentricity of 0.48 and an inclination of 7° with respect to the ecliptic.[8] A first precovery was taken at Palomar Observatory during the Digitized Sky Survey in 1990, extending the body's observation arc by 11 years prior to its official discovery observation at Socorro.[2]
It has an Earth minimum orbital intersection distance (MOID) of Script error: No such module "convert"., which translates into 20.3 lunar distances.[8] With an Earth MOID above 0.05 AU, Template:Mp is no longer a potentially hazardous asteroid, but it was classified as such by the MPC until early 2017.[2][9]
Radar observations show that it measures 2.5 kilometers in diameter.[3] Its surface has a low albedo of 0.048.[10] Rotational lightcurves obtained from photometric observations gave a rotation period of 3.423 hours (best result) with a brightness variation between 0.13 and 0.27 magnitude (U=2/3/3Script error: No such module "Check for unknown parameters".).[7][11]Template:Efn Radar observations gave a concurring period of 3.4256 hours, and subsequent modeling of both radiometric and photometric observations gave a spin axis of (309.0°, −80.0°) in ecliptic coordinates (λ, β).[3]
Triple system
In 2008, scientists using the planetary radar at Arecibo Observatory discovered that the object is orbited by two satellites, when the triple asteroid made a close approach to Earth of 0.066 AU (nearly 10 million kilometers). The largest body (preliminarily called Alpha) is spheroid in shape, with principal axes of Script error: No such module "val". km, Script error: No such module "val". km, and Script error: No such module "val". km, with an effective diameter of Script error: No such module "val". km and a density of Script error: No such module "val". g/cm3. The satellites, named Beta and Gamma, are several times smaller in size. Beta is Script error: No such module "val". km in diameter and Gamma Script error: No such module "val". km.[3]
The only other unambiguously identified triple asteroids in the near-Earth population are (136617) 1994 CC, which was discovered to be a triple system in 2009, and 3122 Florence, which was found to be a triple system in September 2017.[12]
Orbital characteristics of satellites
The orbital properties of the satellites are listed in this table.[13] The orbital planes of both satellites are inclined relative to each other; the relative inclination is about 14 degrees. Such a large inclination is suggestive of past evolutionary events (e.g. close encounter with a terrestrial planet, mean-motion-resonance crossing) that may have excited their orbits from a coplanar configuration to an inclined state.
| Name | Mass (est.) | Semi-major axis | Orbital period | Eccentricity |
|---|---|---|---|---|
| Gamma (inner) | Script error: No such module "val". | 3.8 km | 0.686 days | 0.016 |
| Beta (outer) | Script error: No such module "val". | 16.6 km | 6.225 days | 0.015 |
Exploration
This triple asteroid system is the target for the planned ASTER mission scheduled for launch in 2025 by the Brazilian Space Agency.[14]
Notes
References
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External links
- CBET No. 1254 – Template:Mp, Central Bureau for Astronomical Telegrams
- Robert Roy Britt, Triple Asteroid Found Near Earth, Space.com, 13 Feb 2008
- Emily Lakdawalla, Triple Near-Earth Asteroid Discovered Template:Webarchive The Planetary Society, 13 Feb 2008
- Images of the asteroid and its moons
- A Lander to Investigate a C-type Triple Near-Earth Asteroid System: 2001 SN263
- Dictionary of Minor Planet Names, Google books
- Template:NeoDys
- Template:ESA-SSA
- Template:PAGENAMEBASE at the JPL Small-Body DatabaseTemplate:EditAtWikidata
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