4085 Weir

4085 Weir, provisional designation 1985 JR, is a stony Eunomian asteroid from the central regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 13 May 1985, by astronomer Carolyn Shoemaker at the Palomar Observatory in California, United States. The asteroid was named after American geologist Doris Blackman Weir.[2][3]

4085 Weir
Discovery [1]
Discovered byC. Shoemaker
Discovery sitePalomar Obs.
Discovery date13 May 1985
Designations
(4085) Weir
Named after
Doris Blackman Weir [2][3]
(American geologist)
1985 JR · 1981 JY
1982 XK
main-belt · (middle) [4]
Eunomia [5]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc36.57 yr (13,356 days)
Aphelion2.8838 AU
Perihelion2.3288 AU
2.6063 AU
Eccentricity0.1065
4.21 yr (1,537 days)
261.69°
0° 14m 3.12s / day
Inclination14.220°
68.681°
136.29°
Physical characteristics
Dimensions9.221±0.241 km[6]
9.579±0.048 km[7]
9.66±0.77 km[8]
11.30 km (calculated)[4]
14.602±0.005 h[9][lower-alpha 1]
14.657±0.0046 h[10]
0.20 (assumed)[4]
0.228±0.038[8]
0.2334±0.0274[7]
0.273±0.060[6]
S (Tholen)[4]
12.025±0.001 (R)[10] · 12.1[1][4] · 12.30[7][8] · 12.38±0.22[11]

    Orbit and classification

    Weir is a member of the Eunomia family (502),[5] a prominent family of stony S-type asteroid and the largest one in the intermediate main belt with more than 5,000 members.[12]:23 It orbits the Sun in the central main-belt at a distance of 2.3–2.9 AU once every 4 years and 3 months (1,537 days; semi-major axis of 2.61 AU). Its orbit has an eccentricity of 0.11 and an inclination of 14° with respect to the ecliptic.[1]

    The body's observation arc begins with its first observation as 1981 JY at Anderson Mesa Station in May 1981, or four years prior to its official discovery observation at Palomar.[2]

    Physical characteristics

    In the Tholen classification, Weir is a common, stony S-type asteroid,[4] which is also the overall spectral type for members of the Eunomia family.[12]:23

    Rotation period

    In May 2006, a rotational lightcurve of Weir was obtained from photometric observations by Brian Warner at his Palmer Divide Observatory in Colorado. Lightcurve analysis gave a rotation period of 14.602 hours with a brightness variation of 0.18 magnitude (U=2).[9][lower-alpha 1] A concurring period of 14.657 hours and an amplitude of 0.24 magnitude was measured by astronomers at the Palomar Transient Factory in May 2010 (U=2).[10]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Weir measures between 9.221 and 9.66 kilometers in diameter and its surface has an albedo between 0.228 and 0.273.[6][7][8]

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 11.30 kilometers based on an absolute magnitude of 12.1.[4]

    Naming

    This minor planet was named after American planetary geologist with the United States Geological Survey, Doris Blackman Weir.[2][3] The approved naming citation was published by the Minor Planet Center on 12 December 1989 (M.P.C. 15576).[13]

    Notes
    1. Lightcurve plot of 4085 Weir, Palmer Divide Observatory, B. D. Warner (2006). Rotation period 14.602±0.005 hours with a brightness amplitude of 0.18±0.02 mag. Summary figures at the LCDB

    References
    1. "JPL Small-Body Database Browser: 4085 Weir (1985 JR)" (2017-11-28 last obs.). Jet Propulsion Laboratory. Retrieved 8 January 2018.
    2. "4085 Weir (1985 JR)". Minor Planet Center. Retrieved 8 January 2018.
    3. Schmadel, Lutz D. (2007). "(4085) Weir". Dictionary of Minor Planet Names – (4085) Weir. Springer Berlin Heidelberg. p. 349. doi:10.1007/978-3-540-29925-7_4063. ISBN 978-3-540-00238-3.
    4. "LCDB Data for (4085) Weir". Asteroid Lightcurve Database (LCDB). Retrieved 8 January 2018.
    5. "Asteroid 4085 Weir – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 27 October 2019.
    6. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
    7. 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.
    8. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 8 January 2018.
    9. Warner, Brian D. (December 2006). "Asteroid lightcurve analysis at the Palmer Divide Observatory - March - June 2006". The Minor Planet Bulletin. 33 (4): 85–88. Bibcode:2006MPBu...33...85W. ISSN 1052-8091. Retrieved 8 January 2018.
    10. 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 8 January 2018.
    11. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 8 January 2018.
    12. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
    13. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 8 January 2018.

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