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132 Aethra

132 Aethra
Discovery
Lightcurve-based 3D-model of Aethra
Discovered by	James C. Watson
Discovery date	13 June 1873
Designations
MPC designation	(132) Aethra
Pronunciation	/ˈiːθrə/^[1]
Named after	Aethra
Alternative designations	A873 LA; 1922 XB; 1949 MD; 1953 LF
Minor planet category	Mars crosser
Orbital characteristics^[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	142.50 yr (52049 d)
Aphelion	3.6250 AU (542.29 Gm)
Perihelion	1.5895 AU (237.79 Gm)
Semi-major axis	2.6073 AU (390.05 Gm)
Eccentricity	0.39036
Orbital period (sidereal)	4.21 yr (1537.7 d)
Average orbital speed	17.72 km/s
Mean anomaly	38.271°
Mean motion	0° 14^m 2.796^s / day
Inclination	24.997°
Longitude of ascending node	258.408°
Argument of perihelion	255.216°
Physical characteristics
Mean diameter	42.87±1.6 km^[2] 44.47±0.74 km^[3]
Mass	(1.59 ± 0.89/0.42)×10¹⁷kg^[3]
Mean density	3.447 ± 1.935/0.923 g/cm³^[3]
Synodic rotation period	5.1684 h (0.21535 d)^[2]
Geometric albedo	0.1990±0.015^[2]
Spectral type	M
Absolute magnitude (H)	8.96^[2]

Aethra (minor planet designation: 132 Aethra) is a metallic asteroid and Mars-crosser on an eccentric orbit from the asteroid belt. It measures approximately 40 kilometers in diameter.

It was discovered by James Craig Watson in 1873 and is the first such Mars-crosser asteroid to be identified. As a Mars-crosser asteroid, Aethra is the lowest numbered asteroid to not have proper orbital elements due to recurring perturbations by Mars. It has a rather eccentric orbit that sometimes brings it closer to the Sun than the planet Mars.

With an original observation arc of only 22 days, 132 Aethra was a lost asteroid between 1873 and 1922.^[4]^[5]

The varying light curve of the asteroid implies an elongated or irregular shape for its body.

It is named after Aethra, the mother of TheseusinGreek mythology.

References

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^ ^a ^b ^c ^d ^e "JPL Small-Body Database Browser: 132 Aethra" (2000-06-10 last obs). Retrieved 12 May 2016.

^ ^a ^b ^c Fienga, A.; Avdellidou, C.; Hanuš, J. (February 2020). "Asteroid masses obtained with INPOP planetary ephemerides". Monthly Notices of the Royal Astronomical Society. 492 (1): 589–602. doi:10.1093/mnras/stz3407.

^ Herget, Paul (1938). "The orbit and perturbations of (132) Aethra". Astronomical Journal. 47 (1081): 17–23. Bibcode:1938AJ.....47...17H. doi:10.1086/105455.

^ Fred William Price (2000). The Planet Observer's Handbook. Cambridge University Press. p. 192. ISBN 978-0-521-78981-3.