Discovery date 28 January 1982 Alternative names 1982 BH Discovered 28 January 1982 Discovery site Brorfelde Observatory Moon S/2005 (3309) 1 | MPC designation 3309 Brorfelde Minor planet category main-belt · Hungaria Orbits Sun Asteroid group Hungaria family | |
Discovered by K. Jensen
K. Augustesen Named after Brorfelde Observatory
(discovering observatory) Discoverers K. S. Jensen, Karl Augustesen People also search for 3982 Kastel', 3073 Kursk | ||
3309 Brorfelde, provisional designation 1982 BH, is a nearly spheroidal, binary Hungaria asteroid from the inner regions of the asteroid belt, approximately 4 kilometers in diameter. It was discovered on 28 January 1982, by Danish astronomers Kåre Jensen and Karl Augustesen at Brorfelde Observatory near Holbæk, Denmark. It was named for the discovering observatory and the village where it is located.
Description
Brorfelde is a bright stony asteroid and member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.7–1.9 AU once every 2 years and 5 months (895 days). Its orbit has an eccentricity of 0.05 and an inclination of 21° with respect to the ecliptic. The body's observation arc begins with its official discovery observation, as no precoveries were taken, and no prior identifications were made.
Between 2005 and 2010, astronomers Brian Warner and Petr Pravec obtained a large number of rotational light-curves of Brorfelde. Best rated light-curve analysis gave a rotation period between 2.5041 and 2.5046 hours with a brightness amplitude between 0.09 and 0.13 in magnitude, indicating that the body has a nearly sphereoidal shape (U=3/3/3). These results superseded photometric observations taken by Wiesław Z. Wiśniewski in the 1990s (U=2), and by Federico Manzini and René Roy in 2005 and 2009, respectively (U=2-/n.a.), as well as observations taken at the Palomar Transient Factory in 2010, which gave an incorrect period solution of more than 9 hours (U=1).
During the photometric observation in 2005, it was revealed that Brorfelde is a binary asteroid. Its asteroid moon has an orbital period of 7001184800000000000♠18.48±0.01 hours, and measures approximately 1 kilometer in diameter, based on a mean-diameter ratio of 6999260000000000000♠0.26±0.02 for the system's secondary and primary body. In January 2014, repeated observations by Brian Warner confirmed a period of 2.503 and 18.51 hours for the primary and secondary, respectively (U=3), with several online-published light-curve plots.
On the SMASS taxonomic scheme, Brorfelde is a S-type asteroid. According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Brorfelde measures 3.78 kilometers in diameter, and its surface has an albedo of 0.46 (most recent result only). The Collaborative Asteroid Lightcurve Link derives an albedo of 0.2747 and a diameter of 3.91 kilometers using an absolute magnitude of 14.062.
This minor planet was named on the occasion of the Brorfelde Observatory's 40th anniversary. Brorfelde was the observatory's first minor planet discovery. Naming citation was published on 7 September 1987 (M.P.C. 12210).