(85182) 1991 AQ

(85182) 1991 AQ, provisional designation 1991 AQ, is a stony asteroid on a highly eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.1 kilometers (0.7 miles) in diameter. It was discovered on 14 January 1991, by American astronomer Eleanor Helin at the Palomar Observatory in California.[1] Based on its brightness variation of 0.69 magnitude, this Q-type asteroid is likely elongated.[4] It belongs to the small group of potentially hazardous asteroids larger than one kilometer.

(85182) 1991 AQ
Discovery[1]
Discovered byE. F. Helin
Discovery sitePalomar Obs.
Discovery date14 January 1991
Designations
(85182) 1991 AQ
1991 AQ · 1994 RD
Apollo · NEO · PHA[1][2]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc26.91 yr (9,829 d)
Aphelion3.9474 AU
Perihelion0.4960 AU
2.2217 AU
Eccentricity0.7768
3.31 yr (1,210 d)
64.916°
0° 17m 51.36s / day
Inclination3.1276°
339.68°
242.96°
Earth MOID0.0165 AU (6.428 LD)
Physical characteristics
Mean diameter
1.1 km[3]
1.14 km (derived)[4]
0.18 (assumed)[4]
0.242±0.194[3]
Q (Tholen)[4]
17.1[2]
17.20[4]

    Orbit and classification

    1991 AQ is a member of the Earth-crossing class of Apollo asteroids, the largest group of near-Earth objects with approximately 10 thousand known members.[1][2] It is also a Venus- and Mars-crosser due to its extreme perihelion and aphelion, respectively.[2]

    It orbits the Sun at a distance of 0.5–3.9 AU once every 3 years and 4 months (1,210 days; semi-major axis of 2.22 AU). Its orbit has a high eccentricity of 0.78 and an inclination of 3° with respect to the ecliptic.[2] The body's observation arc begins with its official discovery observation at Palomar in 1991.[1]

    Close approaches

    The asteroid has currently an Earth minimum orbital intersection distance of 0.0165 AU (2,470,000 km; 1,530,000 mi), which corresponds to 6.4 lunar distances and makes it a potentially hazardous asteroid due to its notably large size.[2] In 1991 and 1994, it approached Earth at a nominal distance of 0.054 AU (21 LD). The asteroids closest encounter with Earth is projected to occur on 27 January 2130, at a distance of 0.0106 AU (4.1 LD) only (see table).[5] It also makes close encounters to Mercury, Venus, Mars and Jupiter.[5]

    History of close approaches of large near-Earth objects since 1908 (A)
    PHA Date Approach distance (lunar dist.) Abs.
    mag
    (H)    		 Diameter (C)
    (m)    		 Ref (D)
    Nomi-
    nal(B)    		 Mini-
    mum    		 Maxi-
    mum
    (33342) 1998 WT241908-12-163.5423.5373.54717.9556–1795data
    (458732) 2011 MD51918-09-170.9110.9090.91317.9556–1795data
    (7482) 1994 PC11933-01-172.9272.9272.92816.8749–1357data
    69230 Hermes1937-10-301.9261.9261.92717.5668–2158data
    69230 Hermes1942-04-261.6511.6511.65117.5668–2158data
    (137108) 1999 AN101946-08-072.4322.4292.43517.9556–1795data
    (33342) 1998 WT241956-12-163.5233.5233.52317.9556–1795data
    (163243) 2002 FB31961-04-124.9034.9004.90616.41669–1695data
    (192642) 1999 RD321969-08-273.6273.6253.63016.31161–3750data
    (143651) 2003 QO1041981-05-182.7612.7602.76116.01333–4306data
    2017 CH11992-06-054.6913.3916.03717.9556–1795data
    (170086) 2002 XR141995-06-244.2594.2594.26018.0531–1714data
    (33342) 1998 WT242001-12-164.8594.8594.85917.9556–1795data
    4179 Toutatis2004-09-294.0314.0314.03115.32440–2450data
    2014 JO252017-04-194.5734.5734.57317.8582–1879data
    (137108) 1999 AN102027-08-071.0141.0101.01917.9556–1795data
    (35396) 1997 XF112028-10-262.4172.4172.41816.9881–2845data
    (154276) 2002 SY502071-10-303.4153.4123.41817.6714–1406data
    (164121) 2003 YT12073-04-294.4094.4094.40916.21167–2267data
    (385343) 2002 LV2076-08-044.1844.1834.18516.61011–3266data
    (52768) 1998 OR22079-04-164.6114.6114.61215.81462–4721data
    (33342) 1998 WT242099-12-184.9194.9194.91917.9556–1795data
    (85182) 1991 AQ2130-01-274.1404.1394.14117.11100data
    314082 Dryope2186-07-163.7092.9964.78617.5668–2158data
    (137126) 1999 CF92192-08-214.9704.9674.97318.0531–1714data
    (290772) 2005 VC2198-05-051.9511.7912.13417.6638–2061data
    (A) List includes near-Earth approaches of less than 5 lunar distances (LD) of objects with H brighter than 18.
    (B) Nominal geocentric distance from the Earth's center to the object's center (Earth radius≈0.017 LD).
    (C) Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y.
    (D) Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD)
    (E) Color codes:   unobserved at close approach   observed during close approach   upcoming approaches

    Physical characteristics

    In the Tholen classification, this object is an uncommon Q-type asteroid, that falls into the larger stony S-complex.[4] As of 2018, no rotational lightcurve of this asteroid has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[2] It has a brightness variation of 0.69 magnitude, indicative for an elongated, non-spherical shape.[4]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, this asteroid measures 1.1 kilometers in diameter and its surface has an albedo of 0.242.[3] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.18 and derives a diameter of 1.14 kilometers based on an absolute magnitude of 17.20.[4]

    Numbering and naming

    This minor planet was numbered by the Minor Planet Center on 30 August 2004 (M.P.C. 52517).[6] As of 2018, it has not been named.[1]

    References
    1. "85182 (1991 AQ)". Minor Planet Center. Retrieved 21 April 2018.
    2. "JPL Small-Body Database Browser: 85182 (1991 AQ)" (2017-12-12 last obs.). Jet Propulsion Laboratory. Retrieved 21 April 2018.
    3. 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. S2CID 9341381.
    4. "LCDB Data for (85182)". Asteroid Lightcurve Database (LCDB). Retrieved 21 April 2018.
    5. "JPL Small-Body Database Browser: 85182 (1991 AQ)". Jet Propulsion Laboratory. Retrieved 21 April 2018.
    6. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 21 April 2018.
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