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164 Eva
	3D convex shape model of 164 Eva
Discovery
Discovered by	P. P. Henry
Discovery site	Paris
Discovery date	12 July 1876
Designations
MPC designation	(164) Eva
Pronunciation	/ˈiːvə/
Named after	Unknown
Alternative designations	A876 NA
Minor planet category	Main belt
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	118.93 yr (43438 d)
Aphelion	3.5444 AU (530.23 Gm)
Perihelion	1.7188 AU (257.13 Gm)
Semi-major axis	2.6338 AU (394.01 Gm)
Eccentricity	0.34577
Orbital period (sidereal)	4.27 yr (1561.2 d)
Mean anomaly	219.5472°
Mean motion	0° 13m 50.128s / day
Inclination	24.4564°
Longitude of ascending node	76.8519°
Argument of perihelion	283.9561°
Earth MOID	0.882286 AU (131.9881 Gm)
Jupiter MOID	2.44116 AU (365.192 Gm)
TJupiter	3.191
Physical characteristics
Dimensions	104.87±1.9 km; 101.77 ± 3.61 km
Mass	(9.29 ± 7.76) × 1017 kg
Mean density	1.68 ± 1.41 g/cm3
Equatorial surface gravity	2.249 cm/s (mean)
Equatorial escape velocity	4.857 cm/s (mean)
Synodic rotation period	13.66 h (0.569 d); 13.672 h
Geometric albedo	0.0447±0.002
Temperature	170 K (mean)
Spectral type	C
Absolute magnitude (H)	8.89, 8.84

164 Eva is a main-belt asteroid that was discovered by the French brothers Paul Henry and Prosper Henry on July 12, 1876, in Paris. The reason the name Eva was chosen remains unknown, though Karl Ludwig Littrow suspected a "worldly origin" ("Mit dem Namen könnten wir wie bei Miriam wieder den biblischen Boden zu betreten glauben, wenn wir bei diesem Entdecker nicht an Taufen weltlichen Ursprungs gewöhnt wären").^[6] The orbital elements for 164 Eva were published in 1877 by American astronomer Winslow Upton.^[7] It is categorized as a C-type asteroid and is probably composed of primitive carbonaceous chondritic materials.

Photometric observations of this asteroid at the Palmer Divide Observatory in Colorado Springs, Colorado, during 2008 gave a light curve with a period of 13.672 ± 0.003 hours and a small brightness variation of 0.04 ± 0.01 in magnitude. This is consistent with a previous study reported in 1982 that listed a period estimate of 13.66 hours.^[4]

Between 2000 and 2021, 164 Eva has been observed to occult fourteen stars.

With a perihelion of 1.718 AU 164 Eva is the closest asteroid over 100 kilometers to approach the orbit of Mars. Its closest approach is about 0.05 AU or about 19.5 lunar distances.^[8]

References

^ "Eva". Dictionary.com Unabridged (Online). n.d.
^ ^a ^b ^c ^d Yeomans, Donald K., "164 Eva", JPL Small-Body Database, archived from the original on 4 March 2019, retrieved 12 May 2016.
^ ^a ^b ^c Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73 (1): 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
^ ^a ^b Warner, Brian D. (January 2009), "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2008 May - September", The Minor Planet Bulletin, 36 (1): 7–13, Bibcode:2009MPBu...36....7W.
^ Warner, Brian D. (December 2007), "Initial Results of a Dedicated H-G Project", The Minor Planet Bulletin, 34 (4): 113–119, Bibcode:2007MPBu...34..113W.
^ Schmadel, Lutz D. (2012), Dictionary of Minor Planet Names, Springer, pp. 28, 1341, ISBN 978-3642297182.
^ Upton, Winslow (July 1877), "Elements of (164) Eva", Astronomische Nachrichten, 90 (6): 85–86, Bibcode:1877AN.....90...85U, doi:10.1002/asna.18770900605.
^ NASA.gov