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.

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.

Optical observations have found two satellites of this asteroid. Once the orbits are known, Elektra's mass can be reliably found. The value of 6.6×10¹⁸ kg indicates a density of 1.3 ± 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.

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. 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
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
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
Mass	~4×1014 kg
Equatorial escape velocity	~ 4 m/s
Absolute magnitude (H)	14.5

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
Discovered by	Christian Heinrich Friedrich Peters
Discovery date	February 17, 1873
Designations
Named after	Electra
Minor planet category	Main belt
Orbital characteristics
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
Mass	6.6±0.4×1018 kg 1.28±0.10×1019 kg
Mean density	1.3 ± 0.3 g/cm3 3.8 ± 0.3 g/cm3
Equatorial surface gravity	0.07 m/s2
Equatorial escape velocity	0.13 km/s
Sidereal rotation period	0.230103 d (5.52247 h)
Axial tilt	157°
Pole ecliptic latitude	-88°
Pole ecliptic longitude	68°
Geometric albedo	0.076 ± 0.011
Surface temp. min mean max Kelvin ~157 251 Celsius -23°
Spectral type	G
Absolute magnitude (H)	7.12

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)