(15692) 1984 RA

(15692) 1984 RA, provisional designation 1984 RA, is a Hungaria asteroid from the innermost regions of the asteroid belt, approximately 2 kilometers (1.2 miles) in diameter. It was discovered on 1 September 1984, by Italian astronomer Maria Barucci at the Palomar Observatory in California, United States.[1] The presumed E-type asteroid has a longer-than average rotation period of 37.4 hours and possibly an elongated shape.[3]

(15692) 1984 RA
Discovery [1]
Discovered byM. Barucci
Discovery sitePalomar Obs.
Discovery date1 September 1984
Designations
(15692) 1984 RA
1984 RA · 1986 JT1
1992 SZ26
main-belt · (inner)[2]
Hungaria [1][3][4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc41.44 yr (15,135 d)
Aphelion2.1225 AU
Perihelion1.7302 AU
1.9264 AU
Eccentricity0.1018
2.67 yr (977 d)
138.59°
0° 22m 6.96s / day
Inclination23.217°
142.60°
273.05°
Physical characteristics
Mean diameter
1.728±0.273 km[5][6]
2.43 km (calculated)[3]
37.44±0.05 h[7][lower-alpha 1]
0.30 (assumed)[3]
0.780±0.146[5][6]
E (assumed)[3]
14.7[6]
14.85±0.97[8]
14.9[2]
15.0[3]

    Orbit and classification

    1984 RA is a bright core member of the Hungaria family (003),[4] a large family of three thousand asteroids located within the dynamical group with the same name.[1][3] Hungarias form the innermost dense concentration of asteroids in the Solar System; they are inside the asteroid belt's core region, sometimes considered a completely independent population.[9]

    The asteroid orbits the Sun in the innermost asteroid belt at a distance of 1.7–2.1 AU once every 2 years and 8 months (977 days; semi-major axis of 1.93 AU). Its orbit has an eccentricity of 0.10 and an inclination of 23° with respect to the ecliptic.[2] The body's observation arc begins with a precovery found in the Digitized Sky Survey and taken at the Siding Spring Observatory in November 1977, almost 7 years prior to its official discovery observation at Palomar.[1]

    Physical characteristics

    1984 RA is an assumed E-type asteroid, known for their high albedos, typically around 0.4.[3]

    Rotation period

    In July 2013, a rotational lightcurve of this asteroid was obtained from photometric observations by American astronomer Brian Warner at the Palmer Divide Station (U82) in California. Lightcurve analysis gave a long rotation period of 37.44 hours with a brightness amplitude of 0.66 magnitude, indicative of an elongated shape (U=2).[7][lower-alpha 1] While not being a slow rotator, 1984 RA has a significantly longer period than most asteroids, which rotate once every 2 to 20 hours around their axis.

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, this asteroid measures 1.728 kilometers in diameter and its surface has an exceptionally high albedo of 0.78.[5][6] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 – a compromise value between the E- (0.40) and S-type (0.20) members of the Hungaria family and group, respectively – and calculates a diameter of 2.43 kilometers based on an absolute magnitude of 15.0.[3]

    Numbering and naming

    This minor planet was numbered by the Minor Planet Center on 26 July 2000 (M.P.C. 40991).[10] As of 2018, it has not been named.[1]

    Notes
    1. Lightcure plot of (15692) 1984 RA, by B. D. Warner at the Center for Solar System Studies – Palmer Divide Station (U82). Rotation period 37.44±0.05 hours. Observation from 8 Jul 2013 to 1 Aug 2013. Data points: 273. Quality code is 2. Summary figures at the LCDB

    References
    1. "15692 (1984 RA)". Minor Planet Center. Retrieved 10 May 2018.
    2. "JPL Small-Body Database Browser: 15692 (1984 RA)" (2018-04-26 last obs.). Jet Propulsion Laboratory. Retrieved 10 May 2018.
    3. "LCDB Data for (15692)". Asteroid Lightcurve Database (LCDB). Retrieved 10 May 2018.
    4. "Asteroid (15692) 1984 RA – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 27 October 2019.
    5. 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.
    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. (catalog)
    7. Warner, Brian D. (January 2014). "Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2013 June- September". The Minor Planet Bulletin. 41 (1): 27–32. Bibcode:2014MPBu...41...27W. ISSN 1052-8091.
    8. 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.
    9. 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.
    10. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 10 May 2018.

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