1003 Lilofee

Lilofee (minor planet designation: 1003 Lilofee), provisional designation 1923 OK, is a carbonaceous Themistian asteroid from the outer regions of the asteroid belt, approximately 33 kilometers in diameter. It was discovered on 13 September 1923, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany.^[14] The asteroid was named after the Black Forest mermaid "Lilofee" from German folklore.^[2]

1003 Lilofee

Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	13 September 1923
Designations
MPC designation	(1003) Lilofee
Named after	Lilofee[2] (mermaid in German folklore)
Alternative designations	1923 OK · 1937 FB 1940 TA · 1951 QO 1951 RA2 · 1957 WD2 1962 QH · A915 HB
Minor planet category	main-belt · (outer) Themis[3][4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	93.81 yr (34,263 days)
Aphelion	3.6414 AU
Perihelion	2.6373 AU
Semi-major axis	3.1394 AU
Eccentricity	0.1599
Orbital period (sidereal)	5.56 yr (2,032 days)
Mean anomaly	211.31°
Mean motion	0° 10m 37.92s / day
Inclination	1.8402°
Longitude of ascending node	139.45°
Argument of perihelion	317.42°
Physical characteristics
Dimensions	27.29±1.83 km[5] 32.292±0.334 km[6] 33.1±3.3 km[7] 33.678±0.334 km[8] 34.04 km (calculated)[3] 36±4 km[9]
Synodic rotation period	8.230±0.004 h[10] 8.24991±0.00005 h[11] 8.250±0.001 h[12][a] 8.2506±0.0003 h[10] 8.255±0.002 h[10]
Geometric albedo	0.07±0.01[9] 0.08±0.02[3][7] 0.130±0.020[8] 0.1406±0.0213[6] 0.198±0.028[5]
Spectral type	C[3]
Absolute magnitude (H)	10.20[5][6] · 10.50±0.22[13] · 10.70[3][7][9] · 10.8[1]

Orbit and classification

Lilofee is a member of the Themis family (602),^[3][4] a very large family of carbonaceous, low-inclination asteroids, named after 24 Themis.^[15]: 23 It orbits the Sun in the outer main-belt at a distance of 2.6–3.6 AU once every 5 years and 7 months (2,032 days). Its orbit has an eccentricity of 0.16 and an inclination of 2° with respect to the ecliptic.^[1]

The asteroid was first identified as A915 HB at Bergedorf Observatory in April 1915. The body's observation arc begins with its official discovery observation at Heidelberg.^[14]

Physical characteristics

Lilofee is an assumed carbonaceous C-type asteroid,^[3] which corresponds to the overall spectral type of the Themis family.^[15]: 23

Lightcurves

Since 2004, several rotational lightcurves of Lilofee were obtained from photometric observations by astronomers René Roy, Enric Forné and Robert Stephens. Lightcurve analysis gave a rotation period of 8.255 hours with a brightness variation of 0.57 magnitude (U=2+/3/3).^[10][12][a]

In 2013, an international study modeled a lightcurve with a concurring period of 8.24991 hours and found a spin axis of (n.a., −99.0°) in ecliptic coordinates (λ, β).^[11]

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Lilofee measures between 27.29 and 36 kilometers in diameter and its surface has an albedo between 0.07 and 0.198.^{[5][6][7][8][9]}

The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.08 and calculates a diameter of 34.04 kilometers based on an absolute magnitude of 10.7.^[3]

Naming

This minor planet was named after the legendary mermaid/neck Lilofee, who lived in the small Mummelsee of the Black Forest in southwest Germany. Lilofee is also the title figure in the German folk-song The beautiful young Lilofee ("Die schöne junge Lilofee") by August Schnezler (1809–1853).^[2]

The asteroid was named by the discoverer (RI 402). The name was proposed by ARI-astronomer Johannes Riem, after whom 1025 Riema was named. The official naming citation was also mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 96).^[2]

Notes

1. Lightcurve plot of (1003) Lilofee by R. D. Stephens (2013) at CS3. Rotation period 8.250±0.001 hours with a brightness amplitude of 0.54±0.02 mag. Summary figures at Collaborative Asteroid Lightcurve Link