_Tirela.png) Modelled shape of Tirela from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | L. Boyer |
| Discovery site | Algiers Obs. |
| Discovery date | 17 November 1936 |
| Designations | |
| (1400) Tirela | |
Named after | Charles Tirel[2] (discoverer's friend) |
| 1936 WA · 1930 UQ | |
| main-belt · (outer)[3] Tirela[4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 86.96 yr (31,762 days) |
| Aphelion | 3.8513AU |
| Perihelion | 2.4001 AU |
| 3.1257 AU | |
| Eccentricity | 0.2322 |
| 5.53yr (2,018 days) | |
| 316.88° | |
| 0° 10m 42.24s / day | |
| Inclination | 15.631° |
| 210.10° | |
| 111.65° | |
| Physical characteristics | |
| 13.356 h[8] | |
| 0.216±0.031[6] 0.2165±0.0309[7] 0.227±0.022[5] | |
| C(assumed)[3] | |
| 11.3[7] · 11.4[1][3] · 11.50[5] | |
1400 Tirela (provisional designation1936 WA) is anasteroid and the parent body of theTirela family, located in the outer regions of theasteroid belt. It was discovered on 17 November 1936, by French astronomerLouis Boyer at theAlgiers Observatory in North Africa.[9] The asteroid has arotation period of 13.4 hours and measures approximately 16 kilometers (9.9 miles) in diameter. It was named after Charles Tirel, a friend of the discoverer.[2]
Tirela is the parent body of theTirela family,[4] a fairly largeasteroid family, also known as the Klumpkea family, after its largest member1040 Klumpkea.[10]: 23 It orbits the Sun in theouter main belt at a distance of 2.4–3.9 AU once every 5 years and 6 months (2,018 days). Its orbit has aneccentricity of 0.23 and aninclination of 16° with respect to theecliptic.[1] The asteroid was first identified as1930 UQ atLowell Observatory in October 1930. The body'sobservation arc also begins at Lowell Observatory, with aprecovery taken the night before its first identification.[9]
Thisminor planet was named after Charles Tirel a friend of discovererLouis Boyer-[2] The official naming citation was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 127).[2]
In both the Tholen- and SMASS-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2), Tirela is a darkD-type asteroid.[4][11] Conversely, the overallspectral type of theTirela family is that of anS-type which agrees with the determined albedo(see below) byWISE and Akari.[10]: 23
In the early 2000s, a rotationallightcurve of Tirela was obtained from photometric observations by a group of Hungarian astronomers. Lightcurve analysis gave arotation period of 13.356 hours with a brightness amplitude of 0.55magnitude (U=2),[8] superseding the result from a previous observation that gave a period of 8 hours.[a] A 2016-published lightcurve, using modeled photometric data from the Lowell Photometric Database, gave a concurring sidereal period of13.35384±0.00001 hours, as well as two spin axis of (58.0°, −80.0°) and (297.0°, −41.0°) inecliptic coordinates (λ, β).[12]
According to the surveys carried out by the JapaneseAkari satellite and theNEOWISE mission of NASA'sWISE telescope, Tirela measures between 14.67 and 15.697 kilometers in diameter and its surface has analbedo between 0.216 and 0.227.[5][6][7] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 29.21 kilometers based on anabsolute magnitude of 11.4.[3]
