130 Elektra

S/2014 (130) 1
Physical characteristics
Dimensions	2 km

S/2003 (130) 1
Discovery
Discovered by	, ,; , ,; , and
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

130 Elektra
	VLT image of Elektra (filtered, center) and its moons (left)
Discovery
Discovered by	C. H. F. Peters
Discovery site	Litchfield Obs.
Discovery date	17 February 1873
Designations
MPC designation	(130) Elektra
Pronunciation	/ɪˈlɛktrə/
Named after	Electra
Minor planet category	Main belt
Adjectives	Elektrian /ɪˈlɛktriən/
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	122.35 yr (44690 d)
Aphelion	3.77969 AU (565.434 Gm)
Perihelion	2.47815 AU (370.726 Gm)
Semi-major axis	3.12892 AU (468.080 Gm)
Eccentricity	0.20799
Orbital period	5.53 yr (2021.6 d)
Mean anomaly	128.885°
Mean motion	0° 10m 41.084s / day
Inclination	22.8461°
Longitude of ascending node	145.401°
Argument of perihelion	236.231°
Known satellites	S/2003 (130) 1; S/2014 (130) 1
Physical characteristics
Dimensions	182.25±11.8 km; 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
Rotation period	5.225 h (0.2177 d)
Sidereal rotation period	0.230103 d (5.52247 h)
Axial tilt	157°
Pole ecliptic latitude	-88°
Pole ecliptic longitude	68°
Geometric albedo	0.0755±0.011; 0.076 ± 0.011
Spectral type	G
Absolute magnitude (H)	7.12

Elektra (minor planet designation: 130 Elektra) is a large outer main-belt asteroid. It was discovered on 17 February 1873, by astronomer Christian Peters at Litchfield Observatory, New York, and named after Electra, an avenger in Greek mythology.

Description[]

Lightcurve-based 3D-model of 130 Elektra

The spectrum of 130 Elektra 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^[16] and it displays evidence of aqueous alteration.^[17]

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.^[18]^[19]

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.^[14]

Occultations[]

Elektra has been observed to pass in front of a dozen stars since 2007, most notably on April 21, 2018 when over 30 mostly citizen astronomers spread across five European countries recorded the sudden drop in light of an 11th magnitude star. The sky-plane plot of the chords reveals a peanut-shaped body, possibly the result of a two-body merger early in the history of the Solar System.

Shape of Elektra as observed from Europe on April 21, 2018.

Satellites[]

Elektra (brightness muted) and its two moons

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. It was given the provisional designation S/2003 (130) 1. Due to only a few observations to date, its orbit is still relatively loosely constrained.^[11] In December 2014 a smaller inner moon, about 2 km across and orbiting Elektra about three times closer than S/2003 (130) 1, was discovered using the SPHERE instrument on the VLT's Melipal (UT3) telescope. It was provisionally named S/2014 (130) 1.^[20]

References[]

^ Discovery Circumstances: Numbered Minor Planets, Minor Planet Centre
^ "Electra". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
^ George William Cox (1878) History of Greece
^ "The Asteroid Orbital Elements Database". astorb. Lowell Observatory.^{[permanent dead link]}
^ Jump up to: ^a ^b ^c ^d "130 Elektra". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 12 May 2016.
^ Based in IRAS mean diameter of 182±12 km, a/b ratio of 1.4 as per the following references
^ Jump up to: ^a ^b ^c Supplemental IRAS Minor Planet Survey Archived 2009-08-17 at the Wayback Machine
^ 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).
^ Jump up to: ^a ^b ^c 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.
^ Jump up to: ^a ^b ^c 130 Elektra and S/2003 (130) 1 Archived 2007-07-24 at the Wayback Machine, orbit data website maintained by F. Marchis.
^ Error estimate derived from consideration of $M\propto a^{3}/P^{2}$ and given errors in a and P. See propagation of uncertainty.
^ Jump up to: ^a ^b On the extremities of the long axis.
^ Jump up to: ^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 (1): 39–63. Bibcode:2006Icar..185...39M. doi:10.1016/j.icarus.2006.06.001. PMC 2600456. PMID 19081813.
^ PDS node taxonomy database Archived 2009-08-05 at the Wayback Machine
^ Cruikshank, D. P. & Brown, R. H. (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.
^ Fornasier, S.; et al. (February 1999), "Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites", Astronomy and Astrophysics Supplement, 135: 65–73, Bibcode:1999A&AS..135...65F, doi:10.1051/aas:1999161.
^ 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
^ 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.
^ "Elektra: A New Triple Asteroid". www.eso.org. European Southern Observatory. Retrieved 9 May 2016.
^ IAUC 8183 Archived 2006-05-01 at the Wayback Machine
^ Assuming a similar density to the primary.

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)
Occultation Prediction Software (David Herald)
130 Elektra at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
130 Elektra at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

[1] Discovery Circumstances: Numbered Minor Planets, Minor Planet Centre

[2] "Electra". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)

[3] George William Cox (1878) History of Greece

[lowell-4] "The Asteroid Orbital Elements Database". astorb. Lowell Observatory.^{[permanent dead link]}

[jpldata-5] Jump up to: ^a ^b ^c ^d "130 Elektra". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 12 May 2016.

[about-6] Based in IRAS mean diameter of 182±12 km, a/b ratio of 1.4 as per the following references

[IRAS-7] Jump up to: ^a ^b ^c Supplemental IRAS Minor Planet Survey Archived 2009-08-17 at the Wayback Machine

[pds_spin-8] PDS node spin vector database (in particular, the synthetic compiled value of a/b=1.4).

[johnston-9] (130) Elektra and S/2003 (130) 1, at Johnston's archive (maintained by W. R. Johnston).

[Marchis2008-10] Jump up to: ^a ^b ^c 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.

[marchis-11] Jump up to: ^a ^b ^c 130 Elektra and S/2003 (130) 1 Archived 2007-07-24 at the Wayback Machine, orbit data website maintained by F. Marchis.

[error-12] Error estimate derived from consideration of $M\propto a^{3}/P^{2}$ and given errors in a and P. See propagation of uncertainty.

[pointyend-13] Jump up to: ^a ^b On the extremities of the long axis.

[MarKaaHom06-14] Jump up to: ^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 (1): 39–63. Bibcode:2006Icar..185...39M. doi:10.1016/j.icarus.2006.06.001. PMC 2600456. PMID 19081813.

[PDStax-15] PDS node taxonomy database Archived 2009-08-05 at the Wayback Machine

[CruBro87-16] Cruikshank, D. P. & Brown, R. H. (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.

[Fornasier1999-17] Fornasier, S.; et al. (February 1999), "Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites", Astronomy and Astrophysics Supplement, 135: 65–73, Bibcode:1999A&AS..135...65F, doi:10.1051/aas:1999161.

[Durech2007-18] 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

[19] 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.

[20] "Elektra: A New Triple Asteroid". www.eso.org. European Southern Observatory. Retrieved 9 May 2016.

[iauc8183-21] IAUC 8183 Archived 2006-05-01 at the Wayback Machine

[mass-22] Assuming a similar density to the primary.

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Discovery^[21]
Discovered by	, , , , , and
Discovery date	15 August 2003
Designations
Minor planet category	Main belt
Orbital characteristics^[10]
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 ^[14]
Mass	~4×10¹⁴ kg ^[22]
Equatorial escape velocity	~ 4 m/s
Absolute magnitude (H)	14.5^[14]