| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 29 October 1918 |
| Designations | |
| (904) Rockefellia | |
Named after | John D. Rockefeller[2] (Americanbusiness magnate) |
| A918 UC · 1949 UK 1961 AK · A913 UD A916 KC · 1918 EO 1913 UD · 1916 KC | |
| main-belt[1][3] · (outer) background[4][5] | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 106.24yr (38,805 d) |
| Aphelion | 3.2567AU |
| Perihelion | 2.7366 AU |
| 2.9967 AU | |
| Eccentricity | 0.0868 |
| 5.19 yr (1,895 d) | |
| 178.00° | |
| 0° 11m 24s / day | |
| Inclination | 15.147° |
| 198.08° | |
| 251.78° | |
| Physical characteristics | |
| 6.826±0.004 h[9] | |
| 10.4[1][3] | |
904 Rockefellia (prov. designation:A918 UCor1918 EO) is a dark and largebackground asteroid from the outer regions of theasteroid belt, that measures approximately 59 kilometers (37 miles) in diameter. It was discovered on 29 October 1918, by German astronomerMax Wolf at theHeidelberg-Königstuhl State Observatory.[1] The carbonaceousC-type asteroid (Ch) has arotation period of 6.8 hours and is rather spherical in shape. It was named after American philanthropist and oil industrialistJohn D. Rockefeller (1839–1937).[2]
Rockefellia is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[4][5] It orbits the Sun in theouter asteroid belt at a distance of 2.7–3.3 AU once every 5 years and 2 months (1,895 days;semi-major axis of 3 AU). Its orbit has aneccentricity of 0.09 and aninclination of 15° with respect to theecliptic.[3] The asteroid was first observed asA913 UD (1913 UD) at theSimeiz Observatory on 28 October 1913, and three nights later atHeidelberg Observatory as well. The body'sobservation arc begins at Heidelberg on 6 December 1918, or five weeks after its official discovery observation.[1]
Thisminor planet was named afterJohn D. Rockefeller (1839–1937), an Americanphilanthropist andoilman who founded theRockefeller Foundation. The officialnaming citation was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 87).[2]
In the Tholen- and SMASS-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2),Rockefellia is a Caa and Ch type, respectively, both indicating that it is a hydrated, carbonaceousC-type asteroid.[5][10]
In December 2017, a rotationallightcurve ofRockefellia was obtained fromphotometric observations byTom Polakis at the Command Module Observatory (V02) in Arizona. Lightcurve analysis gave arotation period of6.826±0.004 hours with a low brightness variation of0.14±0.03magnitude (U=2).[9] The result supersedes tentative period determinations byPierre Antonini (2009), Stephane Fauvaud (2011) andRené Roy (2014), which were of lower quality (U=1/2/1).[11][12][13]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE), the Infrared Astronomical SatelliteIRAS, and the JapaneseAkari satellite,Rockefellia measures (49.146±0.763), (58.75±1.7) and (61.36±0.77) kilometers in diameter and its surface has analbedo of (0.055±0.009), (0.0561±0.003) and (0.051±0.002), respectively.[6][7][8] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0357 and calculates a diameter of 58.51 kilometers based on anabsolute magnitude of 10.4.[11] Alternativemean diameter measurements published by the WISE team include (48.96±16.97 km), (52.127±3.976 km), (54.859±14.983 km) and (55.321±19.554 km) with corresponding albedos of (0.05±0.05), (0.071±0.010) and (0.04±0.03) and (0.042±0.033).[5][11]
On 13 May 2005, anasteroid occultation gave a best-fit ellipse dimension of 59.0 × 59.0 kilometers.[5] These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is rated poorly. A second, lower rated observation on 23 February 2013, measured an ellipse of 61.0 × 61.0 kilometers.[5]
