258 Tyche

Tyche (minor planet designation: 258 Tyche) is a relatively large main belt asteroid discovered by Robert Luther at Düsseldorf-Bilk Observatory on 4 May 1886.[1] The stony S-type asteroid measures about 65 kilometers in diameter and has a perihelion of 2.1 AU.[1]

This article is about the asteroid. For the hypothetical planet, see Tyche (hypothetical planet).
258 Tyche
Light curve-based 3D-model of 258 Tyche
Discovery [1]
Discovered byR. Luther
Discovery siteDüsseldorf-Bilk Obs.
Discovery date4 May 1886
Designations
(258) Tyche
Pronunciation/ˈtaɪkiː/[2]
Named after
Tyche [3]
Eunomia · main-belt
Orbital characteristics [1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc129.95 yr (47465 d)
Aphelion3.1512 AU (471.41 Gm)
Perihelion2.0838 AU (311.73 Gm)
2.6175 AU (391.57 Gm)
Eccentricity0.20390
4.23 yr (1546.8 d)
18.42 km/s
157.95°
0° 13m 57.864s / day
Inclination14.305°
207.59°
155.01°
Earth MOID1.09016 AU (163.086 Gm)
Jupiter MOID2.34517 AU (350.832 Gm)
TJupiter3.334
Physical characteristics
Dimensions64.78±1.2 km [1]
65 km [4]
Mass~ 4×1017 (estimate)
Mean density
~ 2.7 g/cm³[5]
10.041 h (0.4184 d) [1][6]
0.1676±0.006 [1]
0.168 [4]
Temperature~ 169 K
max: 268 K
B–V = 0.876
U–B = 0.459
S (Tholen), S (SMASS)
8.50

    Tyche orbits very close to the Eunomia family of asteroids, and could be a member based on composition. However, it is larger than all family members apart from 15 Eunomia while lying at the very edge of the family group. Hence, there is a good chance that it is an unrelated interloper.

    There is some uncertainty regarding Tyche's rotation period. Various authors give values from 9.983 to 10.041 hours.[7]

    It was named after Greek goddess of fortune, Tyche, which is also the name of one of the Oceanids. Tyche's Roman equivalent is Fortuna, after which the asteroid 19 Fortuna is named.[3]

    References
    1. "JPL Small-Body Database Browser: 258 Tyche" (2015-09-21 last obs.). Jet Propulsion Laboratory. Retrieved 11 May 2016.
    2. Noah Webster (1884) A Practical Dictionary of the English Language
    3. Schmadel, Lutz D. (2003). Dictionary of Minor Planet Names – (258) Tyche. Springer Berlin Heidelberg. p. 38. doi:10.1007/978-3-540-29925-7_259. ISBN 978-3-540-29925-7.
    4. Supplemental IRAS Minor Planet Survey Archived June 23, 2006, at Archive.today
    5. G. A. Krasinsky et al. Hidden Mass in the Asteroid Belt, Icarus, Vol. 158, p. 98 (2002).
    6. PDS lightcurve data Archived June 14, 2006, at Archive.today
    7. D. Riccioli, C. Blanco, & M. Cigna Rotational periods of asteroids II, Planetary and Space Science, Vol. 49,, p. 657 (2001).

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