2204 Lyyli
Dark asteroid
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2204 Lyyli (prov. designation: 1943 EQ) is a dark asteroid and very eccentric Mars-crosser from the middle region of the asteroid belt, approximately 25 kilometers (16 miles) in diameter. It was discovered on 3 March 1943 by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Finland.[3]
_Lyyli.png)
Shape model of Lyyli from its lightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | Y. Väisälä |
| Discovery site | Turku Obs. |
| Discovery date | 3 March 1943 |
| Designations | |
| (2204) Lyyli | |
Named after | Lyyli Heinänen (Esperantist)[2] |
| 1943 EQ · 1968 DN | |
| Mars-crosser[1][3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 73.75 yr (26,937 days) |
| Aphelion | 3.6435 AU |
| Perihelion | 1.5354 AU |
| 2.5894 AU | |
| Eccentricity | 0.4071 |
| 4.17 yr (1,522 days) | |
| 350.25° | |
| Inclination | 20.561° |
| 160.45° | |
| 283.25° | |
| Earth MOID | 0.6872 AU |
| Mars MOID | 0.2547 AU |
| Physical characteristics | |
| 25.16±2.4 km (IRAS:11)[4] 25.27 km (derived)[5] 27.12±1.31 km[6] | |
| 9.51±0.01 h[7] 10 h[8] 11.063±0.001 h[9] 11.09±0.01 h[10] | |
| 0.020±0.002[6] 0.0232±0.005 (IRAS:11)[4] 0.050±0.006[11] 0.0537 (derived)[5] | |
| SMASS = X[1] · P[11] · X[5] | |
| 11.61±0.44[12] · 11.78[5] · 12.1[1] · 12.70[4][6] | |
Orbit and classification
Lyyli orbits the Sun in the central main-belt at a distance of 1.5–3.6 AU once every 4 years and 2 months (1,522 days). Its orbit has an eccentricity of 0.41 and an inclination of 21° with respect to the ecliptic.[1]
Naming
This minor planet was named in honour of Lyyli Heinänen (1903–1988), née Hartonen, a Finnish female Esperantist, professor of mathematics, amateur astronomer and former assistant of the discoverer.[2] The official naming citation was published by the Minor Planet Center on 26 May 1983 (M.P.C. 7944).[13]
Physical characteristics
Lyyli is an X-type asteroid in the SMASS classification.[1] It has also been characterized as a P-type asteroid by NASA's NEOWISE mission.[11]
It has a rotation period of 11 hours[9] and a very low albedo between 0.02 and 0.05, according to the surveys carried out by IRAS, Akari, and WISE/NEOWISE.[4][6][11] Other large Mars crossing minor planets include 132 Aethra and 323 Brucia, with diameters of 43 and 36 kilometers, respectively.
