(432949) 2012 HH₂ is a resonant trans-Neptunian object, approximately 255 kilometers (160 miles) in diameter, located in the outermost region of the Solar System.[3] It was discovered by Slovak astronomer Tomáš Vorobjov from images taken on the night of 19 April 2012, at the Astronomical Research Institute (H21) in Illinois, United States. This minor planet was numbered (432949) by the Minor Planet Center on 4 April 2015 (M.P.C. 93615).[5] As of 2021^[update], it has not been named.

(432949) 2012 HH₂

Discovery animation by the Astronomical Research Institute of 2012 HH2
Discovery[1]
Discovered by	T. Vorobjov
Discovery site	Astronomical Research Institute (H21)
Discovery date	19 April 2012
Designations
MPC designation	(432949) 2012 HH2
Alternative designations	2012 HH2
Minor planet category	TNO[2] · res 4:5[3][4]
Orbital characteristics[2]
Epoch 1 July 2021 (JD 2459396.5)
Uncertainty parameter 2
Observation arc	19.16 yr (6,998 d)
Aphelion	40.414 AU
Perihelion	29.201 AU
Semi-major axis	34.808 AU
Eccentricity	0.1611
Orbital period (sidereal)	205.36 yr (75,008 d)
Mean anomaly	40.568°
Mean motion	0° 0m 17.28s / day
Inclination	28.585°
Longitude of ascending node	56.464°
Argument of perihelion	100.49°
Physical characteristics
Mean diameter	255 km (est.)[3]
Geometric albedo	0.09 (est.)[3]
Absolute magnitude (H)	6.38[1][2]

2012 HH₂ is a resonant trans-Neptunian object in an uncommon 4:5 resonance with Neptune (DES: 5:4E).[3][4] It orbits the Sun at a distance of 29.2–40.4 AU once every 205 years and 4 months (75,008 days; semi-major axis of 34.81 AU). Its orbit has an eccentricity of 0.16 and an inclination of 29° with respect to the ecliptic.[2] It is currently 29.8 AU from the Sun.

As of 2021^[update], no rotational lightcurve of 2012 HH₂ has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[2] Johnston's Archive estimates a mean-diameter of 255 kilometers (160 miles), using a standard magnitude-to-diameter conversion with an assumed albedo of 0.09.[3] Astronomer Mike Brown gives a nearly identical estimates of 253 kilometers (160 miles) for the object's diameter with an albedo of 0.08 and an absolute magnitude of 6.3.[6]

References

External links

• MPEC 2012-H36 : DAILY ORBIT UPDATE (2012 APR. 21 UT) (Discovery mention on Daily Orbit Update)
• MPEC 2012-L20 : 2012 HH2 (Revision to MPEC 2012-J31)
• Home page of the Astronomical Research Institute
• (432949) 2012 HH2 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters