130 Elektra

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. The light curve of (130) Elektra forms a double sinusoid while the shape model is elongated and the derived rotation axis is perpendicular to the plane of the ecliptic.[2][3] Optical observations have found two satellites of this asteroid. Once the orbits are known, Elektra's mass can be reliably found. The value of 6.6×10^18 kg indicates a density of 1.3 ± 0.3 g/cm^3. 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] Satellites S/2003 (130) 1 and S/2014 (130) 1 In 2003, a small moon of (130) 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] In December 2014 a slightly smaller moon, orbiting Elektra about three times closer than S/2003 (130) 1, was discovered using the SPHERE instrument on the VLT's Melipal (UT3) telescope. This second satellite has been provisionally named S/2014 (130) 1. S/2003 (130) 1 Discovery[6] 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[7] Semi-major axis 1318 ± 25 km Eccentricity 0.13 ± 0.03 Orbital period 5.258 ± 0.0053 d Average orbital speed 23 m/s Inclination 3 Satellite of 130 Elektra Physical characteristics Dimensions 7 ± 3 km [4] Mass ~4×10^14 kg [8] Equatorial escape velocity ~ 4 m/s Absolute magnitude (H) 14.5[4] S/2014 (130) 1 Discovery Discovered by B. Yang, Z. Wahhaj, M. Marsset, J. Milli, C. Dumas, and F. Marchis Discovery date December 6, 2014 Designations Minor planet category Main belt Orbital characteristics Semi-major axis 460 Eccentricity ? Orbital period 1.1 d Inclination ? Satellite of 130 Elektra Physical characteristics Dimensions 5.2 ± 1.2 km

130 Elektra A three-dimensional model of 130 Elektra based on its light curve. Discovery[9] Discovered by Christian Heinrich Friedrich Peters Discovery date February 17, 1873 Designations Named after Electra 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° Known satellites S/2003 (130) 1 S/2014 (130) 1 Physical characteristics Dimensions 215×155 ± 12 km[11][12][13][14] Mass 6.6±0.4×10^18 kg[7] 1.28±0.10×10^19 kg[5][15] Mean density 1.3 ± 0.3 g/cm^3[7] 3.8 ± 0.3 g/cm^3[5] Equatorial surface gravity 0.07 m/s^2[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. min mean max Kelvin ~157 251 Celsius -23° Spectral type G [17] Absolute magnitude (H) 7.12 [12]

References

1. D.P. Cruikshank & R.H. Brown (1987). "Organic Matter on Asteroid 130 Elektra". Science 238 (4824): 183–4. Bibcode:1987Sci...238..183C. doi:10.1126/science.238.4824.183. PMID 17800458.
2. Durech, J.; et al. (April 2007), "Physical models of ten asteroids from an observers' collaboration network", Astronomy and Astrophysics 465 (1): 331–337, Bibcode:2007A&A...465..331D, doi:10.1051/0004-6361:20066347.
3. Durech, J.; Kaasalainen, M.; Marciniak, A.; Allen, W. H. (2007). "Asteroid brightness and geometry". Astronomy and Astrophysics 465 (1): 331–337. Bibcode:2007A&A...465..331D. doi:10.1051/0004-6361:20066347.
4. F. Marchis; et al. (2006). "Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey". Icarus 185 (1): 39–63. Bibcode:2006Icar..185...39M. doi:10.1016/j.icarus.2006.06.001. PMC 2600456. PMID 19081813.
5. 130 Elektra and S/2003 (130) 1, orbit data website maintained by F. Marchis.
6. IAUC 8183
7. Marchis, Franck; P. Descamps; J. Berthier; D. hestroffer; F. vachier; M. Baek; et al. (2008). "Main Belt Binary Asteroidal Systems With Eccentric Mutual Orbits". Icarus 195 (1): 295–316. arXiv:0804.1385. Bibcode:2008Icar..195..295M. doi:10.1016/j.icarus.2007.12.010.
8. Assuming a similar density to the primary.
9. Discovery Circumstances: Numbered Minor Planets, Minor Planet Centre
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. 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 $M \propto a^3/P^2$ and given errors in a and P. See propagation of uncertainty.
16. On the extremities of the long axis.
17. PDS node taxonomy database

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)
• 130 Elektra at the JPL Small-Body Database

• Discovery · Orbit diagram · Orbital elements · Physical parameters