 Lightcurve-base 3D-model of 140 Siwa. | |
| Discovery | |
|---|---|
| Discovered by | J. Palisa |
| Discovery site | Austrian Naval Obs. |
| Discovery date | 13 October 1874 |
| Designations | |
| (140) Siwa | |
| Pronunciation | /ˈʃiːwə/[citation needed] |
Named after | Živa |
| A874 TB; 1948 AL | |
| Main belt | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 139.10 yr (50805 d) |
| Aphelion | 3.3224 AU (497.02 Gm) |
| Perihelion | 2.14323 AU (320.623 Gm) |
| 2.73283 AU (408.826 Gm) | |
| Eccentricity | 0.21575 |
| 4.52yr (1650.1d) | |
Averageorbital speed | 17.80 km/s |
| 200.674° | |
| 0° 13m 5.398s / day | |
| Inclination | 3.1860° |
| 107.263° | |
| 196.711° | |
| Physical characteristics | |
| Dimensions | 109.79±3.0 km |
| Mass | 1.4×1018 kg |
| 34.445 h (1.4352 d)[1] 34.407 h[2] | |
| 0.0676±0.004 | |
| C-type asteroid[3] | |
| 8.34 | |
140 Siwa is a large and darkmain-beltasteroid that was discovered by Austrian astronomerJohann Palisa on October 13, 1874, and named afterŽiva (Šiwa), aSlavic goddess offertility.
TheRosettacometprobe was to visit Siwa on its way to comet46P/Wirtanen in July, 2008. However, the mission was rerouted to comet67P/Churyumov-Gerasimenko and the flyby had to be abandoned.[4]
Attempts to measure the rotation period of this asteroid have produced inconsistent results ranging from 14.7 to 32 hours.Photometric observations of this asteroid at the Organ Mesa Observatory inLas Cruces, New Mexico during 2010 gave an irregularlight curve with a period of 34.407 ± 0.002 hours and a brightness variation of 0.05 ± 0.01 inmagnitude.[2]
A 2004 study of the spectrum matched a typicalC-type asteroid with typicalcarbonaceous chondrite makeup. There are no absorption features ofmafic minerals found.[3] The classification was later revised to aP-type asteroid.[5]
