130 Elektra

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130 Elektra is a very large outer main belt asteroid. It was discovered by C. H. F. Peters on February 17, 1873 and named after Electra, an avenger in Greek mythology. Its spectrum is of the G type, hence it probably has a Ceres-like composition. Spectral signatures of organic compounds have been seen on Elektra's surface [1]. In the late 1990s, a network of astronomers worldwide gathered lightcurve data that was ultimately used to derive the spin states and shape models of 10 new asteroids, including (130) Elektra. [2][3] Optical observations have found a satellite of this asteroid. Using its orbit, Elektra's mass can be reliably found. The value of 1.3×1019 kg indicates an unusually high density (for asteroids) of 3.8 ± 0.3 g/cm³. Optical observations have also determined that Elektra's shape is quite irregular, as well as giving indications of albedo differences of 5-15% on its surface[4]. This is uncommon, and corroborates with Elektra's high density to indicate that it is probably a solid, rather than fractured or rubble pile, body. [edit] Satellite (S/2003 (130) 1) In 2003, a small moon of Elektra was detected using the Keck II telescope. The diameter of the satellite is 4 km and it orbits at a distance of about 1170 km. The satellite has been given the provisional designation S/2003 (130) 1. Due to only a few observations to date, its orbit is still relatively loosely constrained [5]. S/2003 (130) 1 Discovery[6] and designation Discovered by W. J. Merline, P. M. Tamblyn, C. Dumas, L. M. Close, C. R. Chapman, and F. Menard Discovery date 15 August , 2003 Designations Minor planet category Main belt Orbital characteristics[5] Semi-major axis 1252 ± 30 km Eccentricity unknown, likely small Orbital period 3.92 ± 0.03 d Average orbital speed 23 m/s Inclination uncertain Satellite of 130 Elektra Physical characteristics Dimensions 6 ± 2 km [4] Mass ~4×1014 kg [7] Equatorial escape velocity ~ 4 m/s Absolute magnitude 14.5[4]

130 Elektra Discovery[8] and designation Discovered by Christian Heinrich Friedrich Peters Discovery date February 17, 1873 Designations Alternative names[9]   Minor planet category Main belt Orbital characteristics[10] Epoch December 31, 2006 (JD 2454100.5) Aphelion 565.778 Gm (3.782 AU) Perihelion 369.263 Gm (2.468 AU) Semi-major axis 467.521 Gm (3.125 AU) Eccentricity 0.210 Orbital period 2017.954 d (5.52 a) Average orbital speed 16.66 km/s Mean anomaly 225.604° Inclination 22.838° Longitude of ascending node 145.635° Argument of perihelion 234.753° Satellites S/2003 (130) 1 Physical characteristics Dimensions 215×155 ± 12 km[11][12][13][14] Mass 1.28±0.10×1019 kg [5][15] Mean density 3.8 ± 0.3 g/cm³ [5] Equatorial surface gravity 0.07 m/s²[16] Equatorial escape velocity 0.13 km/s[16] Sidereal rotation period 0.230103 d (5.52247 h)[4] Axial tilt 157° Pole ecliptic latitude -88°[4] Pole ecliptic longitude 68° Geometric albedo 0.076 ± 0.011 [12] Surface temp.    Kelvin    Celsius min mean max ~157 251 -23° Spectral type G [17] Absolute magnitude 7.12 [12]

[edit] References

1. ^ "Organic Matter on Asteroid 130 Elektra" (1987). Science 238: 183. 
2. ^ Durech., J.; Kaasalainen, M., Marciniak, A.; et al., “Physical models of ten asteroids from an observers' collaboration network,” Astronomy and Astrophysics , Volume 465, Issue 1, April I 2007, pp. 331-337
3. ^ Durech, J.; Kaasalainen, M.; Marciniak, A.; Allen, W. H. et al. “Asteroid brightness and geometry,” Astronomy and Astrophysics, Volume 465, Issue 1, April I 2007, pp. 331-337.
4. ^ ^{a b c d e} F. Marchis et al (2006). "Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey". Icarus 185: 39. doi:10.1016/j.icarus.2006.06.001. 
5. ^ ^{a b c d} 130 Elektra and S/2003 (130) 1, orbit data website maintained by F. Marchis.
6. ^ IAUC 8183
7. ^ Assuming a similar density to the primary.
8. ^ Discovery Circumstances: Numbered Minor Planets, Minor Planet Centre
9. ^ [1]
10. ^ ASTORB orbital elements database, Lowell Observatory
11. ^ Based in IRAS mean diameter of 182±12 km, a/b ratio of 1.4 as per the following references
12. ^ ^{a b c} Supplemental IRAS Minor Planet Survey
13. ^ PDS node spin vector database (in particular, the synthetic compiled value of a/b=1.4).
14. ^ (130) Elektra and S/2003 (130) 1, at Johnston's archive (maintained by W. R. Johnston).
15. ^ Error estimate derived from consideration of and given errors in a and P. See propagation of uncertainty.
16. ^ ^{a b} On the extremities of the long axis.
17. ^ PDS node taxonomy database

[edit] External links

• 130 Elektra and S/2003 (130) 1, orbit data website maintained by F. Marchis. Includes adaptive optics image of primary, and satellite orbit diagram.
• Data on (130) Elektra from Johnston's archive (maintained by W. R. Johnston)

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