| Discovery[1] | |
|---|---|
| Discovered by | S. Arend |
| Discovery site | Uccle Obs. |
| Discovery date | 25 November 1948 |
| Designations | |
| (1565) Lemaitre | |
Named after | Georges Lemaître (astronomer, priest)[2] |
| 1948 WA | |
| Mars-crosser[1][3] · Phocaea[4][5] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 68.44 yr (24,997 days) |
| Aphelion | 3.2262AU |
| Perihelion | 1.5613 AU |
| 2.3938 AU | |
| Eccentricity | 0.3478 |
| 3.70yr (1,353 days) | |
| 236.28° | |
| 0° 15m 57.96s / day | |
| Inclination | 21.485° |
| 261.16° | |
| 116.34° | |
| Physical characteristics | |
| Dimensions | 6.90±1.45 km[6] 7.949±1.558 km[7] 8.00±0.58 km[8] 8.76 km(calculated)[4] |
| 2.4±0.1h[9] 11.403±0.003 h[10] | |
| 0.22±0.14[6] 0.23(assumed)[4] 0.239±0.096[7] 0.334±0.051[8] | |
| SMASS = Sq[1] · S[4] | |
| 12.30[8] · 12.5[1][4][7] · 12.95[6] | |
1565 Lemaître (provisional designation1948 WA) is a highly eccentric Phocaeaasteroid and sizableMars-crosser from the inner regions of theasteroid belt, approximately 8 kilometers in diameter. It was discovered on 25 November 1948, by Belgian astronomerSylvain Arend at theRoyal Observatory of Belgium in Uccle, Belgium.[3] It was named after cosmologist and priestGeorges Lemaître.[2]
Lemaître is aMars-crossing asteroid, as it crosses the orbit of Mars at 1.666 AU. It is also an eccentric member of thePhocaea family (701).[5] This asteroid orbits the Sun at a distance of 1.6–3.2 AU once every 3 years and 8 months (1,353 days). Its orbit has aneccentricity of 0.35 and aninclination of 21° with respect to theecliptic.[1] As noprecoveries were taken, and no prior identifications were made, Lemaître'sobservation arc begins on the night following its official discovery observation.[3]
In theSMASS taxonomy, Lemaître is characterized as a Sq-type, a transitional class of stonyS-type andQ-type asteroids.[1]
In September 2007, a rotationallight-curve of Lemaître was obtained from photometric observations by American astronomerBrian D. Warner at his Palmer Divide Observatory, Colorado. It gave arotation period of 11.403 hours with a brightness variation of 0.04magnitude (U=2), superseding a provisional period of 2.4 hours with an amplitude of 0.03 magnitude, derived from photometric observations made by Arnaud Leroy, Bernard Trégon, Xavier Durivaud and Federico Manzini two months earlier (U=1+).[9]
According to the surveys carried out by the JapaneseAkari satellite and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission, Lemaître measures between 6.90 and 8.00 kilometers in diameter, and its surface has analbedo between 0.22 and 0.334.[6][7][8] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for Phocaea asteroids of 0.23 – derived from25 Phocaea, the family's most massiv member and namesake – and calculates a diameter of 8.76 kilometers based on anabsolute magnitude of 12.5.[4]
Thisminor planet was named in honour of Belgian priest, astronomer and professor of physics,Georges Lemaître (1894–1966), widely regarded as the father of theBig Bang theory. The lunar craterLemaître also bears his name. Lemaître was the first minor planet to be numbered after the end of World War II.[2] The officialnaming citation was published by theMinor Planet Center on 1 June 1975 (M.P.C. 3824).[11]
