| Discovery [1] | |
|---|---|
| Discovered by | C. Shoemaker E. Shoemaker |
| Discovery site | Palomar Obs. |
| Discovery date | 23 April 1985 |
| Designations | |
| (3581) Alvarez | |
Named after | Luis Alvarez Walter Alvarez (American scientists)[1] |
| 1985 HC · 1962 JL 1971 KE · 1981 TG4 | |
| Mars crosser [1][2][3] | |
| Orbital characteristics [2] | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 56.37yr (20,590 d) |
| Aphelion | 3.9009AU |
| Perihelion | 1.6506 AU |
| 2.7757 AU | |
| Eccentricity | 0.4053 |
| 4.62 yr (1,689 d) | |
| 79.224° | |
| 0° 12m 47.16s / day | |
| Inclination | 28.858° |
| 217.47° | |
| 107.59° | |
| Mars MOID | 0.5301 AU |
| TJupiter | 3.0440 |
| Physical characteristics | |
| 13.69±1.37 km[4] | |
| 33.42±0.02 h[5][a] | |
| 0.113[4] | |
| SMASS =B [2][6][7] | |
| 12.10[8][6] 12.2[1][2] 12.30[4] 12.4[3][9][10] | |
3581 Alvarez, provisional designation1985 HC, is a carbonaceousasteroid and a very largeMars-crosser on an eccentric orbit from theasteroid belt, approximately 13.7 kilometers (8.5 miles) in diameter. It was discovered on 23 April 1985, by American astronomer coupleCarolyn andEugene Shoemaker at thePalomar Observatory in California.[1] The likely sphericalB-type asteroid has arotation period of 33.4 hours.[3] It was named for scientistsLuis Alvarez and his sonWalter Alvarez.[1]
Alvarez is aMars-crossing asteroid, a dynamically unstable group between themain belt and thenear-Earth populations, crossing the orbit ofMars at 1.66 AU.[1][2] However, due to the high inclination of its orbit, it never actually passes through the orbit of Mars since at perihelion it is well away from Mars' orbital plane.[11] It orbits the Sun at a distance of 1.7–3.9 AU once every 4 years and 7 months (1,689 days;semi-major axis of 2.78 AU). Its orbit has aneccentricity of 0.41 and aninclination of 29° with respect to theecliptic.[2] The body'sobservation arc begins with its first observation as1962 JL atGoethe Link Observatory in May 1962, almost 23 years prior to its official discovery observation atPalomar.[1]
Thisminor planet was named after planetary scientistWalter Alvarez (born 1940) and his Nobel-prize winning father, physicistLuis Walter Alvarez (1911–1988).[1] Both atUniversity of California, Berkeley, they are best known for the discovery of a global geochemical anomaly of noble metals at theK-T boundary, which led to hypothesis that the dinosaurs were killed by anasteroid impact(also seeAlvarez hypothesis). The officialnaming citation was published by theMinor Planet Center on 2 February 1988 (M.P.C. 12807),[12] just a few months after the naming was announcement on the occasion of the secondConference on Global Catastrophes in Earth History, held in October 1987 atSnowbird, Utah.[13]
In theSMASS classification,Alvarez is a carbonaceousB-type asteroid, somewhat "brighter" than the more commonC-type asteroids.[2]
In September 2004, a rotationallightcurve ofAlvarez was obtained fromphotometric observations by American photometrist William Koff at the Antelope Hills Observatory (H09) in Bennett, Colorado. Lightcurve analysis gave a longer-than-averagerotation period of33.42±0.02 hours with a small brightness amplitude of0.06±0.02magnitude (U=2), indicative of a spherical rather than elongated shape.[5][a] The result supersedes a previous period determination byWiesław Wiśniewski from 1990, which gave a period of at least 24 hours (U=1).[10]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Alvarez measures 13.69 kilometers in diameter and its surface has analbedo of 0.113.[4] Previously published WISE data from 2013 and 2016 gave a concurring diameter of 14 and 13.7 kilometer with an albedo of 0.14 and 0.13, respectively.[8][6] TheCollaborative Asteroid Lightcurve Link assumes an albedo of 0.057 and derives a diameter of 18.43 kilometers based on anabsolute magnitude of 12.4.[3]
With a diameter close to 14 kilometers,Alvarez is larger than most sizeableMars-crossing asteroids such as1065 Amundsenia (9.75 km),1139 Atami (9.35 km),1011 Laodamia (7.39 km),1727 Mette (5.44 km),1131 Porzia (7.13 km),1235 Schorria (5.55 km),985 Rosina (8.18 km) and1468 Zomba (7 km), comparable with1310 Villigera (15.24 km) and1474 Beira (15.46 km), but still smaller than the largest members of this dynamical group, namely,132 Aethra,323 Brucia (former Mars-crosser),1508 Kemi,2204 Lyyli and512 Taurinensis, which are larger than 20 kilometers in diameter in at least one of the publications.
