130 Elektra

From Wikipedia, the free encyclopedia

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, a revenger 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].

Recent optical observations have found a satellite (see below). 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^[2]. 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 from 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 ^[3].

**S/2003 (130) 1**
Discovery^[4] 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
Minor planet category:	Main belt
Orbital characteristics^[3]
Semi-major axis:	1252 ± 30 km
Eccentricity:	unknown, likely small
Orbital period:	3.92 ± 0.03 d
Avg. orbital speed:	23 m/s
Inclination:	uncertain
Satellite of:	130 Elektra
Physical characteristics
Dimensions:	6 ± 2 km ^[2]
Mass:	~4×10¹⁴ kg ^[5]
Equatorial Escape velocity:	~ 4 m/s
Absolute magnitude:	14.5^[2]

130 Elektra

Discovery^[6] and Designation

Discovered by:

Christian Heinrich Friedrich Peters

Discovery date:

February 17, 1873

Alternative names: [1]

Minor planet category:

Main belt

Orbital characteristics^[7]

Epoch December 31, 2006 (JD 2454100.5)

Aphelion distance:

565.778 Gm (3.782 AU)

Perihelion distance:

369.263 Gm (2.468 AU)

Semi-major axis:

467.521 G m (3.125 AU)

Eccentricity:

0.210

Orbital period:

2017.954 d (5.52 a)

Avg. 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^[8]^[9]^[10]^[11]

Mass:

1.28±0.10×10¹⁹ kg ^[3]^[12]

Mean density:

3.8 ± 0.3 g/cm³ ^[3]

Equatorial surface gravity:

0.07 m/s²^[13]

Equatorial Escape velocity:

0.13 km/s^[13]

Sidereal rotation period:

0.230103 d (5.52247 h)^[2]

Axial tilt:

157°

Pole ecliptic latitude:

-88°^[2]

Pole ecliptic longitude:

68°

Geometric albedo:

0.076 ± 0.011 ^[9]

Surface temp.:
Kelvin
Celsius

min	mean	max
	~157	251
		-23°

Spectral type:

G ^[14]

Absolute magnitude:

7.12 ^[9]

[edit] References

^ (1987) "Organic Matter on Asteroid 130 Elektra". Science 238: 183.
^ ^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.
^ ^a ^b ^c ^d 130 Elektra and S/2003 (130) 1, orbit data website maintained by F. Marchis.
^ IAUC 8183
^ Assuming a similar density to the primary.
^ Discovery Circumstances: Numbered Minor Planets, Minor Planet Centre
^ ASTORB orbital elements database, Lowell Observatory
^ Based in IRAS mean diameter of 182±12 km, a/b ratio of 1.4 as per the following references
^ ^a ^b ^c Supplemental IRAS Minor Planet Survey
^ PDS node spin vector database (in particular, the synthetic compiled value of a/b=1.4).
^ (130) Elektra and S/2003 (130) 1, at Johnston's archive (maintained by W. R. Johnston).
^ Error estimate derived from consideration of $M \propto a^3/P^2$ and given errors in a and P. See propagation of uncertainty.
^ ^a ^b On the extremities of the long axis.
^ 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)