3309 Brorfelde

3309 Brorfelde, provisional designation 1982 BH, is a nearly spheroidal, binary[lower-alpha 1] 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 Kaare Jensen and Karl Augustesen at the Brorfelde Observatory near Holbæk, Denmark.[3] It was named for the discovering observatory and the village where it is located.[2]

3309 Brorfelde
Discovery [1]
Discovered byK. Jensen
K. Augustesen
Discovery siteBrorfelde Obs.
Discovery date28 January 1982
Designations
(3309) Brorfelde
Named after
Brorfelde Observatory
(discovering observatory)[2]
1982 BH
main-belt · Hungaria [3][4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc35.25 yr (12,876 days)
Aphelion1.9143 AU
Perihelion1.7208 AU
1.8175 AU
Eccentricity0.0532
2.45 yr (895 days)
76.394°
0° 24m 7.92s / day
Inclination21.136°
29.797°
218.43°
Known satellites1 [5][lower-alpha 1]
Physical characteristics
Dimensions3.78±0.60 km[6]
3.91 km (derived)[4]
5.038±0.083 km[7]
2.503±0.001 h[8]
2.5041±0.0002 h[5][9]
2.5042±0.0001 h[10]
2.5046±0.0003 h[11]
6±2 h[12]
8±1 h[13]
9.3788±0.0022 h[14]
0.253±0.060[7]
0.2747 (derived)[4]
0.408±0.060[7]
0.46±0.24[6]
SMASS = S [1] · S [4]
13.4±0.2 (R)[5] · 13.584±0.001 (R)[14] · 13.60[6][7] · 13.7[1] · 13.9[9] · 13.97±0.09[12] · 14.062±0.064[4][15]

    Orbit and classification

    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.[1] The body's observation arc begins with its official discovery observation, as no precoveries were taken, and no prior identifications were made.[3]

    Physical characteristics

    On the SMASS taxonomic scheme, Brorfelde is a common stony S-type asteroid.[1]

    Photometry

    Between 2005 and 2010, astronomers Brian Warner and Petr Pravec obtained a large number of rotational lightcurves of Brorfelde. Best rated lightcurve 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 spheroidal shape (U=3/3/3).[9][10]

    These results superseded photometric observations taken by Wiesław Z. Wiśniewski in the 1990s (U=2),[12] and by Federico Manzini and René Roy in 2005 and 2009, respectively (U=2-/n.a.),[13] 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).[14]

    Satellite

    During the photometric observation in 2005, it was revealed that Brorfelde is a binary asteroid. Its asteroid moon has an orbital period of 18.48±0.01 hours, and measures approximately 1 kilometer in diameter, based on a mean-diameter ratio of 0.26±0.02 for the system's secondary and primary body.[lower-alpha 1][5] 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),[8] with several online-published lightcurve plots.[lower-alpha 2]

    Diameter and albedo

    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).[6] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.2747 and a diameter of 3.91 kilometers with an absolute magnitude of 14.062.[4]

    Naming

    This minor planet was named on the occasion of the Brorfelde Observatory's 40th anniversary. Brorfelde was the observatory's first minor planet discovery.[2] The approved naming citation was published by the Minor Planet Center on 7 September 1987 (M.P.C. 12210).[16]

    Notes
    1. Electronic Telegram No. 279, (3309) Brorfelde, 7 November 2005 [lower-alpha 1]
      Photometric observations obtained from 25 October to 3 November 2005, revealed that 3309 Brorfelde is a binary system with an orbital period of 18.48±0.01 hours. The primary rotates with a period of 2.5041±0.0002 hours, and its light-curve has a brightness variation of 0.13 magnitude, indicating a nearly spheroidal shape. Mutual eclipse/occultation events with an amplitude of 0.07-0.15 magnitude suggest a ratio of 0.26±0.02 for its secondary-to-primary mean-diameter. Assuming G = 0.15, the calibrated data gives an absolute magnitude of 13.4±0.2.
      B. D. Warner, Palmer Divide Observatory, Colorado Springs; P. Pravec and P. Kusnirak, Ondrejov Observatory; W. Cooney, J. Gross, and D. Terrell, Sonoita Research Observatory, Sonoita, AZ; and S. Nudds, Elginfield Observatory, University of Western Ontario Central Bureau for Astronomical Telegrams No.279
    2. Lightcure plots of (3309) Brorfelde at the Center for Solar System Studies (CS3) in 2014

    References
    1. "JPL Small-Body Database Browser: 3309 Brorfelde (1982 BH)" (2017-05-02 last obs.). Jet Propulsion Laboratory. Retrieved 3 July 2017.
    2. Schmadel, Lutz D. (2007). "(3309) Brorfelde". Dictionary of Minor Planet Names – (3309) Brorfelde. Springer Berlin Heidelberg. p. 276. doi:10.1007/978-3-540-29925-7_3310. ISBN 978-3-540-00238-3.
    3. "3309 Brorfelde (1982 BH)". Minor Planet Center. Retrieved 9 January 2017.
    4. "LCDB Data for (3309) Brorfelde". Asteroid Lightcurve Database (LCDB). Retrieved 9 January 2017.
    5. Warner, B. D.; Pravec, P.; Kusnirak, P.; Cooney, W.; Gross, J.; Terrell, D.; et al. (November 2005). "(3309) Brorfelde". Central Bureau Electronic Telegrams. 279 (279): 1. Bibcode:2005CBET..279....1W. Retrieved 9 January 2017.
    6. Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 9 January 2017.
    7. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 9 January 2017.
    8. Warner, Brian D. (July 2014). "Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2014 January-March". The Minor Planet Bulletin. 41 (3): 144–155. Bibcode:2014MPBu...41..144W. ISSN 1052-8091. Retrieved 9 January 2017.
    9. Warner, Brian D.; Pravec, Petr; Kusnirak, Peter; Harris, Alan W.; Cooney, Walter R., Jr.; Gross, John; et al. (April 2011). "Lightcurves from the Initial Discovery of Four Hungaria Binary Asteroids". The Minor Planet Bulletin. 38 (2): 107–109. Bibcode:2011MPBu...38..107W. ISSN 1052-8091. Retrieved 9 January 2017.
    10. Pravec, P.; Scheirich, P.; Vokrouhlický, D.; Harris, A. W.; Kusnirák, P.; Hornoch, K.; et al. (March 2012). "Binary asteroid population. 2. Anisotropic distribution of orbit poles of small, inner main-belt binaries". Icarus. 218 (1): 125–143. Bibcode:2012Icar..218..125P. doi:10.1016/j.icarus.2011.11.026. Retrieved 9 January 2017.
    11. Warner, Brian D. (July 2009). "Analysis of the Hungaria Binary Asteroid 3309 Brorfelde". The Minor Planet Bulletin. 36 (3): 108. Bibcode:2009MPBu...36..108W. ISSN 1052-8091. Retrieved 9 January 2017.
    12. Wisniewski, W. Z.; Michalowski, T. M.; Harris, A. W.; McMillan, R. S. (March 1995). "Photoelectric Observations of 125 Asteroids". Abstracts of the Lunar and Planetary Science Conference. 26: 1511. Bibcode:1995LPI....26.1511W. Retrieved 9 January 2017.
    13. Behrend, Raoul. "Asteroids and comets rotation curves – (3309) Brorfelde". Geneva Observatory. Retrieved 9 January 2017.
    14. Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. Retrieved 9 January 2017.
    15. Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026. Retrieved 9 January 2017.
    16. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 9 January 2017.

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