3749 Balam

3749 Balam /ˈbeɪləm/ is a stony Flora asteroid and rare trinary system orbiting in the inner regions of asteroid belt. It also forms a secured asteroid pair with sub-kilometer sized asteroid (312497) 2009 BR60.[5] Balam was discovered on 24 January 1982, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station near Flagstaff, Arizona, and received the prov. designation 1982 BG1. It was named after Canadian astronomer David Balam.[15] Balam measures approximately 4.1 kilometers (2.5 miles) in diameter.[5] Its two minor-planet moons have an estimated diameter of 1.66 and 1.84 kilometers, respectively.

3749 Balam
Shape model of Balam from its lightcurve
Discovery [1]
Discovered byE. Bowell
Discovery siteAnderson Mesa Stn.
Discovery date24 January 1982
Designations
(3749) Balam
Pronunciation/ˈbeɪləm/
Named after
David Balam
(Canadian astronomer)[2]
1982 BG1 · 1954 XM
1962 ED · 1974 YO
main-belt · Flora [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc61.66 yr (22,521 days)
Aphelion2.4818 AU
Perihelion1.9920 AU
2.2369 AU
Eccentricity0.1095
3.35 yr (1,222 days)
254.23°
0° 17m 40.56s / day
Inclination5.3801°
295.71°
173.74°
Known satellites2 (⌀: 1.66 km; 1.84 km)[4]
Physical characteristics
Mean diameter
4.1±0.5 km (primary)[5]
4.663±0.21 km (effective)[6][7]
4.7±0.5 km (effective)[8]
Mass(5.09±0.2)×1014 kg[9][10]
Mean density
2.61±0.45 g/cm3[9][10]
2.805 h[11][12][13][lower-alpha 1]
0.16[14]
0.277±0.096[8]
0.355±0.067[6][7]
Sq [13][14]
13.3[1]
13.4[6]
13.66[3][8][12][lower-alpha 1]

    Orbit and classification

    Balam is a member of the Flora family, a very large group of stony asteroids in the inner main-belt. It orbits the Sun in the inner main-belt at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,222 days). Its orbit has an eccentricity of 0.11 and an inclination of 5° with respect to the ecliptic.[1]

    Naming

    It is named after the Canadian astronomer David Balam, principal observer at Victoria's Climenhaga Observatory in British Columbia.[2] The approved naming citation was published by the Minor Planet Center on 31 May 1988 (M.P.C. 13178).[16]

    Physical characteristics

    The S-type asteroid has an albedo of 0.16.[14] The body's rotation around its axis has been measured several times by different lightcurve observations with a concurring period of 2.8 hours.[11][12][13][lower-alpha 1]

    Outer satellite

    On 13 February 2002, the discovery of a minor-planet moon, provisionally designated S/2002 (3749) 1, was announced by a team of researchers from SwRI, UA, JPL and OSUG, using the Gemini North Telescope on Mauna Kea in Hawaii.[17] It has an estimated diameter of 1.84 kilometers. It orbits 289±13 km away in 61±10 days, with a high orbital eccentricity of ~ 0.9. The distant and highly eccentric orbit of S/2002 (3749) 1 suggests that it was likely captured by Balam.[10]

    Being such a small primary body in the inner main belt with a separation of over 100 primary radii, S/2002 (3749) 1 is the most loosely bound binary known.[18] Balam has a Hill sphere with a radius of about 1,500 kilometers.[10]

    Inner satellite

    In March 2008, Franck Marchis discovered another companion, provisionally designated S/2008 (3749) 1, making Balam a trinary asteroid.[19][20] The inner satellite has a derived diameter of 1.66 kilometer, based on diameter-ratio of 0.42±0.03 with its primary.[4]

    Other known trinary asteroids include 45 Eugenia, 87 Sylvia, 93 Minerva, 107 Camilla, 130 Elektra and 216 Kleopatra.

    Asteroid pair

    Balam also forms an asteroid pair with (312497) 2009 BR60.[5] Asteroid pairs are on highly similar heliocentric orbits. At some point in the past, the pair of asteroids became gravitationally unbound due to rotational fission induced by the YORP-effect or from a collisional breakup of the parent body. After the discovery of Balam's two satellites by Bill Merline (inner moon) and Franck Marchis (outer moon) in 2002 and 2008, respectively, Czech physicist David Vokrouhlický identified the unbound secondary in 2009. Based on backward orbit integrations, it is thought that Balam and 2009 BR60 form a secured asteroid pair that became separated approximately 400,000 years ago.[5]

    Notes
    1. Pravec-2012web, rotation period of 2.80478±0.00005 with an amplitude in brightness variation of 0.1 magnitude. Summary figures for (3749) Balam at Lightcurve Database

    References
    1. "JPL Small-Body Database Browser: 3749 Balam (1982 BG1)" (2016-08-03 last obs.). Jet Propulsion Laboratory. Retrieved 16 June 2017.
    2. Schmadel, Lutz D. (2007). "(3749) Balam". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 317. doi:10.1007/978-3-540-29925-7_3746. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (3749) Balam". Asteroid Lightcurve Database (LCDB). Retrieved 16 June 2017.
    4. Wm. Robert Johnston (13 January 2009). "(3749) Balam, S/2002 (3749) 1, and third component". Johnston's Archive. Retrieved 27 October 2009.
    5. Pravec, P.; Fatka, P.; Vokrouhlický, D.; Scheirich, P.; Ďurech, J.; Scheeres, D. J.; et al. (10 January 2019). "Asteroid pairs: a complex picture". Icarus. 333: 16–18. arXiv:1901.05492. Bibcode:2019Icar..333..429P. doi:10.1016/j.icarus.2019.05.014.
    6. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    7. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
    8. Marchis, F.; Enriquez, J. E.; Emery, J. P.; Mueller, M.; Baek, M.; Pollock, J.; et al. (November 2012). "Multiple asteroid systems: Dimensions and thermal properties from Spitzer Space Telescope and ground-based observations". Icarus. 221 (2): 1130–1161. arXiv:1604.05384. Bibcode:2012Icar..221.1130M. doi:10.1016/j.icarus.2012.09.013.
    9. Jim Baer (12 December 2010). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on 29 January 2009. Retrieved 16 June 2017.
    10. Marchis, F.; Descamps, P.; Berthier, J.; Hestroffer, D.; Vachier, F.; Baek, M.; et al. (May 2008). "Main belt binary asteroidal systems with eccentric mutual orbits". Icarus. 195 (1): 295–316. arXiv:0804.1385. Bibcode:2008Icar..195..295M. doi:10.1016/j.icarus.2007.12.010.
    11. Marchis, F.; Pollock, J.; Pravec, P.; Baek, M.; Greene, J.; Hutton, L.; et al. (March 2008). "(3749) Balam". Central Bureau Electronic Telegrams. 1297: 1. Bibcode:2008CBET.1297....1M.
    12. Polishook, D.; Brosch, N.; Prialnik, D. (March 2011). "Rotation periods of binary asteroids with large separations - Confronting the Escaping Ejecta Binaries model with observations". Icarus. 212 (1): 167–174. arXiv:1012.4810. Bibcode:2011Icar..212..167P. doi:10.1016/j.icarus.2010.12.020.
    13. Polishook, D. (October 2014). "Spin axes and shape models of asteroid pairs: Fingerprints of YORP and a path to the density of rubble piles". Icarus. 241: 79–96. arXiv:1406.3359. Bibcode:2014Icar..241...79P. doi:10.1016/j.icarus.2014.06.018.
    14. Thomas Wm Hamilton (15 April 2014). Dwarf Planets and Asteroids: Minor Bodies of the Solar System. ISBN 9781628577280.
    15. "3749 Balam (1982 BG1)". Minor Planet Center. Retrieved 11 November 2015.
    16. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 16 June 2017.
    17. "IAUC 7827: P/2001 WF_2; S/2002 (3749) 1". IAU Central Bureau for Astronomical Telegrams. 13 February 2002. Retrieved 17 November 2005.
    18. Merline, W. J.; Close, L. M.; Siegler, N.; Dumas, C.; Chapman, C. R.; Rigaut, F.; et al. (September 2002). "Discovery of a Loosely-bound Companion to Main-belt Asteroid (3749) Balam". American Astronomical Society. 34: 835. Bibcode:2002DPS....34.0201M.
    19. "IAUC 8928: V2468 Cyg = N Cyg 2008; (3749)". IAU Central Bureau for Astronomical Telegrams. 19 March 2008. Retrieved 4 February 2012.
    20. Franck Marchis – Principal Investigator, SETI Institute, UC Berkeley. "Franck Marchis Web Page". Department of Astronomy (University of California at Berkeley). Archived from the original on 10 November 2007. Retrieved 27 October 2009.CS1 maint: multiple names: authors list (link)
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