(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]
| Discovery[1] | |
|---|---|
| Discovered by | M. Barucci |
| Discovery site | Palomar Obs. |
| Discovery date | 1 September 1984 |
| Designations | |
MPC designation | (15692) 1984 RA |
Alternative designations | 1984 RA · 1986 JT1 1992 SZ26 |
Minor planet category | main-belt · (inner)[2] Hungaria[1][3][4] |
| Orbital characteristics[2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 41.44 yr (15,135 d) |
| Aphelion | 2.1225 AU |
| Perihelion | 1.7302 AU |
Semi-major axis | 1.9264 AU |
| Eccentricity | 0.1018 |
Orbital period (sidereal) | 2.67 yr (977 d) |
Mean anomaly | 138.59° |
Mean motion | 0° 22m 6.96s / day |
| Inclination | 23.217° |
Longitude of ascending node | 142.60° |
Argument of perihelion | 273.05° |
| Physical characteristics | |
Mean diameter | 1.728±0.273 km[5][6] 2.43 km (calculated)[3] |
Synodic rotation period | 37.44±0.05 h[7][lower-alpha 1] |
Geometric albedo | 0.30 (assumed)[3] 0.780±0.146[5][6] |
Spectral type | E (assumed)[3] |
Absolute magnitude (H) | 14.7[6] 14.85±0.97[8] 14.9[2] 15.0[3] |
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]
1984 RA is an assumed E-type asteroid, known for their high albedos, typically around 0.4.[3]
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.
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]
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]
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