4383 Suruga, provisional designation 1989 XP, is a Vestian asteroid and binary system from the inner regions of the asteroid belt, approximately 6.5 kilometers in diameter. It was discovered on 1 December 1989, by Japanese astronomer Yoshiaki OshimaatGekko Observatory, Japan.[10] The asteroid was named after the former Japanese Suruga Province. Its synchronous minor-planet moon, S/2013 (4383) 1, measures approximately 1.33 kilometers and has a period of 16.386 hours.
Suruga is an orbital member of the Vesta family in the inner main-belt.[3] It orbits the Sun at a distance of 2.3–2.6 AU once every 3 years and 9 months (1,380 days). Its orbit has an eccentricity of 0.06 and an inclination of 7° with respect to the ecliptic.[1]
In February 2013, a rotational lightcurveofSuruga was obtained from photometric observations by American astronomer Brian Warner at his Palmer Divide Observatory (714) in Colorado. Lightcurve analysis gave a well-defined rotation period of 3.4069 hours with a brightness variation of 0.14 magnitude (U=3), which indicates a nearly spheroidal shape.[5]
These observations supersede a period of 3.4069 hours (Δmag 0.08) of an ambiguous lightcurve, obtained by Japanese astronomers during lightcurve survey of V-type asteroids in December 2002 (U=1+).[8]
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Suruga measures 6.471 kilometers in diameter and its surface has an albedo of 0.320,[6][7] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 7.13 kilometers with an absolute magnitude of 13.1.[3]
During Brian Warner's photometric observations in 2013, it was revealed, that Suruga is a synchronous binary system with a minor-planet moon in orbit.[5] The satellite has an orbital period of 16.386. Based on the brightness variations of the mutual eclipsing/occultation events, Warner estimates that the satellite's mean-diameter is at least 21% of that of Suruga's (Ds/Dp of >0.21±0.02).[5] The Johnston's Archive derives a satellite diameter of 1.33 kilometer and estimates a semi-major axis of 11 kilometers for the moon's orbit.[4]
