61 Danaë

61 Danaë

Discovery
Discovered by	H. Goldschmidt
Discovery date	September 9, 1860
Designations
Named after	Danaë
Alternative names	A917 SM; 1953 RL1
Minor planet category	Main belt
Orbital characteristics
Epoch June 14, 2006 (JD 2453900.5)
Aphelion	520.969 Gm (3.482 AU)
Perihelion	371.280 Gm (2.482 AU)
Semi-major axis	446.125 Gm (2.982 AU)
Eccentricity	0.168
Orbital period	1881.025 d (5.15 a)
Average orbital speed	17.13 km/s
Mean anomaly	91.103°
Inclination	18.218°
Longitude of ascending node	333.774°
Argument of perihelion	13.831°
Physical characteristics
Dimensions	82.52 ± 2.73 km
Mass	(2.89 ± 2.78) × 1018 kg
Mean density	9.81 ± 9.49 g/cm3
Surface gravity	0.0126 m/s²
Escape velocity	0.0322 km/s
Rotation period	0.4771 d (11.45 h) [1]
Albedo	0.2224±0.025 [2]
Temperature	~155 K
Spectral type	S
Absolute magnitude (H)	7.68

61 Danaë (/ˈdænəjiː/ DAN-ə-yee or /dəˈneɪ.ə/ də-NAY-ə) is a moderately large, rocky main belt asteroid. It was discovered by Hermann Goldschmidt on September 9, 1860 from his balcony in Paris.

Goldschmidt was ill when asked to name the asteroid, and requested his fellow asteroid-hunter Robert Luther to name it instead. Luther chose to name it after Danaë, the mother of Perseus in Greek mythology. Danaë was the first asteroid to have a diacritical character in its official name.

In 1985, a study of lightcurve data suggested that Danaë may have a moon. If so, the main body would be an ellipsoid measuring 85×80×75 km, and the moon would orbit 101 km away, measuring 55×30×30 km. The density of both would be 1.1 g/cm³.[3]

References

• A. Cellino, R. Pannunzio, V. Zappalà, P. Farinella, and P. Paolicchi, 1985, Do we observe light curves of binary asteroids?, Astronomy and Astrophysics, Vol. 144, No. 2, pp. 355–362.