4957 Brucemurray

4957 Brucemurray, provisional designation 1990 XJ, is a stony asteroid, classified as near-Earth object of the Amor group and as Mars-crosser, approximately 3 kilometers in diameter. It was discovered by American astronomer Eleanor Helin at the Palomar Observatory in California on 15 December 1990.[3] The asteroid was named after American planetary scientist Bruce C. Murray.[2]

4957 Brucemurray
Discovery [1]
Discovered byE. F. Helin
Discovery sitePalomar Obs.
Discovery date15 December 1990
Designations
(4957) Brucemurray
Named after
Bruce C. Murray [2]
(American planetary scientist)
1990 XJ
NEO · Amor [1][3]
Mars-crosser
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc41.35 yr (15,102 days)
Aphelion1.9082 AU
Perihelion1.2228 AU
1.5655 AU
Eccentricity0.2189
1.96 yr (715 days)
282.15°
0° 30m 11.52s / day
Inclination35.011°
254.90°
97.487°
Earth MOID0.4258 AU · 165.9 LD
Physical characteristics
Dimensions3.01 km[4]
3.06 km[5]
3.11 km (calculated)[6]
3.499±0.095 km[7]
2.892 h[8][9]
2.8922 h[10]
0.132±0.023[7]
0.17[5]
0.18[4]
0.18±0.19[11]
0.20 (assumed)[6]
SMASS = S [1][6] · S [12]
B–V = 0.866±0.042[12]
V–R = 0.526±0.018[12]
V–I = 0.956±0.021[12]
14.9[1][6] · 15.1[5] · 15.10±0.3[7]

    Orbit and classification

    Brucemurray orbits the Sun at a distance of 1.2–1.9 AU once every 1 years and 12 months (715 days). Its orbit has an eccentricity of 0.22 and an inclination of 35° with respect to the ecliptic.[1]

    The body's observation arc begins with a precovery taken at the Australian Siding Spring Observatory in March 1976, or more than 14 years prior to its official discovery observation.[3]

    Close approaches

    This deep Mars-crosser makes close approaches both to Earth and Mars. It has an Earth minimum orbital intersection distance of 0.4258 AU (63,700,000 km) which corresponds to 165.9 lunar distances. On 18 May 2033, the asteroid will also pass 0.0684 AU (10,230,000 km) from Mars.[1]

    Physical characteristics

    In the SMASS classification, Brucemurray is a stony S-type asteroid.[1] BVRIZ photometry also found that the asteroid is an S-type NEO.[12]

    Rotation period and axis

    In the 1990s, two rotational lightcurves of Brucemurray were obtained from photometric observations by Czech astronomer Petr Pravec at Ondřejov Observatory. Lightcurve analysis gave a rotation period of 2.892 hours in both cases with a brightness variation of 0.28 and 0.36 magnitude, respectively (U=2/3).[8][9]

    In 2004, an international study modeled a lightcurve with a concurring period of 2.8922 hours and found a spin axis of (358.0°, −50.0°) in ecliptic coordinates (λ, β) (Q=3-).[10]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of Wide-field Infrared Survey Explorer and the ExploreNEOs survey using the Spitzer Space Telescope, Brucemurray measures between 3.01 and 3.499 kilometers in diameter and its surface has an albedo between 0.132 and 0.18.[4][5][7][11]

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 3.11 kilometers based on an absolute magnitude of 14.9.[6]

    Naming

    This minor planet was named after American planetary scientist Bruce C. Murray (1931–2013), director of the Jet Propulsion Laboratory, co-founder of The Planetary Society and professor at California Institute of Technology. This asteroid which comes close both to Mars and Earth, is considered a particularly appropriate object for Murray, who had diligently championed a mission to Mars.[2]

    The official naming citation was published by the Minor Planet Center on 29 November 1993 (M.P.C. 22829).[13]

    References
    1. "JPL Small-Body Database Browser: 4957 Brucemurray (1990 XJ)" (2017-07-16 last obs.). Jet Propulsion Laboratory. Retrieved 15 September 2017.
    2. Schmadel, Lutz D. (2007). "(4957) Brucemurray". Dictionary of Minor Planet Names – (4957) Brucemurray. Springer Berlin Heidelberg. p. 427. doi:10.1007/978-3-540-29925-7_4836. ISBN 978-3-540-00238-3.
    3. "4957 Brucemurray (1990 XJ)". Minor Planet Center. Retrieved 15 September 2017.
    4. Harris, A. W.; Mommert, M.; Hora, J. L.; Mueller, M.; Trilling, D. E.; Bhattacharya, B.; et al. (March 2011). "ExploreNEOs. II. The Accuracy of the Warm Spitzer Near-Earth Object Survey" (PDF). The Astronomical Journal. 141 (3): 10. Bibcode:2011AJ....141...75H. doi:10.1088/0004-6256/141/3/75.
    5. Trilling, D. E.; Mueller, M.; Hora, J. L.; Harris, A. W.; Bhattacharya, B.; Bottke, W. F.; et al. (September 2010). "ExploreNEOs. I. Description and First Results from the Warm Spitzer Near-Earth Object Survey" (PDF). The Astronomical Journal. 140 (3): 770–784. Bibcode:2010AJ....140..770T. doi:10.1088/0004-6256/140/3/770.
    6. "LCDB Data for (4957) Brucemurray". Asteroid Lightcurve Database (LCDB). Retrieved 15 September 2017.
    7. Mainzer, A.; Grav, T.; Masiero, J.; Bauer, J.; Cutri, R. M.; McMillan, R. S.; et al. (November 2012). "Physical Parameters of Asteroids Estimated from the WISE 3-Band Data and NEOWISE Post-Cryogenic Survey". The Astrophysical Journal Letters. 760 (1): 6. arXiv:1210.0502. Bibcode:2012ApJ...760L..12M. doi:10.1088/2041-8205/760/1/L12. S2CID 41459166.
    8. Pravec, Petr; Sarounová, Lenka; Wolf, Marek (December 1996). "Lightcurves of 7 Near-Earth Asteroids". Icarus. 124 (2): 471–482. Bibcode:1996Icar..124..471P. doi:10.1006/icar.1996.0223.
    9. Pravec, Petr; Wolf, Marek; Sarounová, Lenka (November 1998). "Lightcurves of 26 Near-Earth Asteroids". Icarus. 136 (1): 124–153. Bibcode:1998Icar..136..124P. doi:10.1006/icar.1998.5993.
    10. Kaasalainen, Mikko; Pravec, Petr; Krugly, Yurij N.; Sarounová, Lenka; Torppa, Johanna; Virtanen, Jenni; et al. (January 2004). "Photometry and models of eight near-Earth asteroids". Icarus. 167 (1): 178–196. Bibcode:2004Icar..167..178K. doi:10.1016/j.icarus.2003.09.012.
    11. Thomas, C. A.; Trilling, D. E.; Emery, J. P.; Mueller, M.; Hora, J. L.; Benner, L. A. M.; et al. (September 2011). "ExploreNEOs. V. Average Albedo by Taxonomic Complex in the Near-Earth Asteroid Population". The Astronomical Journal. 142 (3): 12. Bibcode:2011AJ....142...85T. doi:10.1088/0004-6256/142/3/85.
    12. Dandy, C. L.; Fitzsimmons, A.; Collander-Brown, S. J. (June 2003). "Optical colors of 56 near-Earth objects: trends with size and orbit". Icarus. 163 (2): 363–373. Bibcode:2003Icar..163..363D. doi:10.1016/S0019-1035(03)00087-3.
    13. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 15 September 2017.
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