2085 Henan

2085 Henan, provisional designation 1965 YA, is a potentially slow rotating asteroid and the parent body of the Henan family in the central regions of the asteroid belt, approximately 15 kilometers in diameter. It was discovered on 20 December 1965, by astronomers at the Purple Mountain Observatory in Nanking, China.^[14] The asteroid was named for the Henan Province in China.^[2]

2085 Henan

Discovery [1]
Discovered by	Purple Mountain Obs.
Discovery site	Purple Mountain Obs.
Discovery date	20 December 1965
Designations
MPC designation	(2085) Henan
Named after	Henan (Province of China)[2]
Alternative designations	1965 YA · 1933 RE 1938 WR · 1949 FL 1949 FP1 · 1962 CL 1963 KA · 1969 VA1 1971 BG1 · 1972 LX 1973 QX1 · 1976 GR7
Minor planet category	main-belt · (outer) Henan [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	68.61 yr (25,060 days)
Aphelion	2.9312 AU
Perihelion	2.4654 AU
Semi-major axis	2.6983 AU
Eccentricity	0.0863
Orbital period (sidereal)	4.43 yr (1,619 days)
Mean anomaly	276.34°
Mean motion	0° 13m 20.64s / day
Inclination	3.8343°
Longitude of ascending node	118.14°
Argument of perihelion	294.54°
Physical characteristics
Dimensions	13.356±0.036 km[4] 13.67 km (calculated)[5] 13.941±0.082 km[6] 16.56±4.50 km[7] 17.61±0.32 km[8] 18 km[9]: 23  18.34±1.20 km[10]
Synodic rotation period	24 h[11] 110±1 h[12]
Geometric albedo	0.10±0.08[7] 0.131±0.019[8] 0.145±0.020[10] 0.18 (assumed)[5] 0.2510±0.0408[6]
Spectral type	SMASS = L [1][5] L (Bus–DeMeo)[12]
Absolute magnitude (H)	11.40[6][10] · 11.55±0.48[13] · 11.60[8] · 11.8[5] · 11.9[1] · 12.12[7]

Orbit and classification

Henan is the parent body of the Henan family (532),^[3] a large family of L-type asteroids in the intermediate main-belt, which can be further divided into four distinct families.^[9]: 23

It orbits the Sun in the central asteroid belt at a distance of 2.5–2.9 AU once every 4 years and 5 months (1,619 days; semi-major axis of 2.70 AU). Its orbit has an eccentricity of 0.09 and an inclination of 4° with respect to the ecliptic.^[1]

A first observation of this asteroid was found on a precovery, taken at the Lowell Observatory in July 1906. The body's observation arc begins at Goethe Link Observatory in July 1943, more than 22 years prior to its official discovery observation at Purple Mountain.^[14]

Physical characteristics

In the Bus–DeMeo and SMASS classification, Henan is an uncommon L-type asteroid,^{[1][5][12]: 5} which is also the overall spectral type for members of the Henan family.^[9]: 23

Rotation period

As of 2017, no secure rotational lightcurve of Henan has been obtained. In September 2004, observations by Laurent Bernasconi gave a rotation period of 24 hours with a brightness variation of 0.25 magnitude (U=1).^[11] In February 2015, photometric observations of Henan by an international collaboration of astronomers gave a tentative synodic period of 110±1 hours and an amplitude of 0.4 magnitude, which would make it a potentially slow rotator (U=1).^[12] An alternative period solution gave 94 hours. The latter study selected Henan because it is a suspected "Barbarian" asteroid (named after 234 Barbara) which polarimetric properties suggest that they have an unusual shape and topographic features with large concave areas.^[12]

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, Henan measures between 13.356 and 18.34 kilometers in diameter and its surface has an albedo between 0.10 and 0.2510.^{[4][6][7][8][10]}

The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.18 and calculates a diameter of 13.67 kilometers based on an absolute magnitude of 11.8.^[5]

Naming

This minor planet was named after the Henan Province in the People's Republic of China, located in the central part of the country along the lower stretch of the Yellow River, which is considered the cradle of civilization in ancient China.^[2] The official naming citation was published by the Minor Planet Center on 1 February 1980 (M.P.C. 5184).^[15]

References

1. "JPL Small-Body Database Browser: 2085 Henan (1965 YA)" (2017-11-02 last obs.). Jet Propulsion Laboratory. Retrieved 18 November 2017.
2. Schmadel, Lutz D. (2007). "(2085) Henan". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 169. doi:10.1007/978-3-540-29925-7_2086. ISBN 978-3-540-00238-3.
3. "Asteroid 2085 Henan – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
4. 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.
5. "LCDB Data for (2085) Henan". Asteroid Lightcurve Database (LCDB). Retrieved 18 November 2017.
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. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
8. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 18 November 2017.
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. 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. (online, AcuA catalog p. 153)
11. Behrend, Raoul. "Asteroids and comets rotation curves – (2085) Henan". Geneva Observatory. Retrieved 18 November 2017.
12. Devogè; le, M.; Tanga, P.; Bendjoya, P.; Rivet, J. P.; Surdej, J.; et al. (July 2017). "Shape and spin determination of Barbarian asteroids". Astronomy & Astrophysics. 607 (119): A119. arXiv:1707.07503. Bibcode:2017A&A...607A.119D. doi:10.1051/0004-6361/201630104.
13. 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 18 November 2017.
14. "2085 Henan (1965 YA)". Minor Planet Center. Retrieved 18 November 2017.
15. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 18 November 2017.