5261 Eureka

5261 Eureka is the first Mars trojan discovered.<ref name=mtrojans>Template:Cite web</ref> It was discovered by David H. Levy and Henry Holt at Palomar Observatory on 20 June 1990.<ref name="schmadel2003"/> It trails Mars (at the Template:L5) at a distance varying by only 0.3 AU during each revolution (with a secular trend superimposed, changing the distance from 1.5–1.8 AU around 1850 to 1.3–1.6 AU around 2400). Minimum distances from Earth, Venus, and Jupiter, are 0.5, 0.8, and 3.5 AU, respectively.

Long-term numerical integration shows that the orbit is stable. Kimmo A. Innanen and Seppo Mikkola note that "contrary to intuition, there is clear empirical evidence for the stability of motion around the Template:L4 and Template:L5 points of all the terrestrial planets over a timeframe of several million years".

Since the discovery of 5261 Eureka, the Minor Planet Center has recognized three other asteroids as Martian trojans: Template:Mpl at the Template:L4 point, Template:Mpl at the Template:L5 point,<ref name=mtrojans/> and Template:Mpl, also at the Template:L5 point.<ref>MPEC 2007-O09 : 2007 NS2</ref> At least five other asteroids in near-1:1 resonances with Mars have been discovered, but they do not exhibit trojan behavior. They are Template:Mpl, Template:Mpl, (36017) 1999 ND₄₃, Template:Mpl and (152704) 1998 SD₄. Due to close orbital similarities, most of the other, smaller, members of the L₅ group are hypothesized to be fragments of 5261 Eureka that were detached after it was spun up by the YORP effect (consistent with its rotational period of 2.69 h).<ref name="Lovett2017">Template:Cite journal</ref>

The infrared spectrum for 5261 Eureka is typical for an A-type asteroid, but the visual spectrum is consistent with an evolved form of achondrite called an angrite. A-class asteroids are tinted red in hue, with a moderate albedo. The asteroid is located deep within a stable Lagrangian zone of Mars, which is considered indicative of a primordial origin—meaning the asteroid has most likely been in this orbit for much of the history of the Solar System.Template:Citation needed

Satellite

On 28 November 2011, a natural satellite of 5261 Eureka was found. This unnamed moon is about 0.46 km in diameter and orbits 2.1 km from Eureka. The satellite's existence was announced in September 2014.<ref>Template:Cite web</ref>

See also

• Template:Mpl
• Template:Mpl
• Template:Mpl
• Template:Mpl
• Template:Mpl
• Template:Mpl
• Template:Mpl
• Template:Mpl
• Template:Mpl
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References

Further reading

• IAUC 5045
• IAUC 5047
• IAUC 5067
• IAUC 5075
• A. S. Rivkin, R. P. Binzel, S. J. Bus, and J. A. Grier, "Spectroscopy and Classification of Mars Trojan Asteroids", Bulletin of the American Astronomical Society 34, 2002, p. 840.
• S. Tabachnik and N. W. Evans, "Cartography for Martian Trojans", The Astrophysical Journal 517, 1999, pp. L63–L66.

External links

• The co-orbital asteroids of Mars A simulation and animation showing Mars's co-orbital and near co-orbital asteroids
• Asteroids with Satellites, Robert Johnston, johnstonsarchive.net
• Template:AstDys
• Template:JPL small body