 Šteins imaged byRosetta | |
| Discovery[1] | |
|---|---|
| Discovered by | N. Chernykh |
| Discovery site | Crimean Astrophysical Obs. |
| Discovery date | 4 November 1969 |
| Designations | |
| (2867) Šteins | |
| Pronunciation | /ˈsteɪns/ |
Named after | Kārlis Šteins[1] |
| |
| Orbital characteristics[2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 66.47yr (24,279 d) |
| Aphelion | 2.7081AU |
| Perihelion | 2.0185 AU |
| 2.3633 AU | |
| Eccentricity | 0.1459 |
| 3.63 yr (1,327 d) | |
| 182.24° | |
| 0° 16m 16.68s / day | |
| Inclination | 9.9354° |
| 55.366° | |
| 251.08° | |
| Physical characteristics | |
| Dimensions | 6.83 km × 5.70 km × 4.42 km[5] |
| 4.92±0.40 km[6] 5.160±0.167 km[7] | |
| 6.049 h[8][a] | |
| 0.300[7] 0.34[6] 0.40[5][9][10] | |
| E[8][9][11] V–R =0.510±0.030[12][13] | |
| 12.7[1][2] 13.36[8][7] 13.36±0.07[6] | |
2867 Šteins (provisional designation1969 VC) is an irregular, diamond-shaped backgroundasteroid from the inner regions of theasteroid belt. Classified as anE-type asteroid, it is approximately 5 kilometers (3.1 miles) in diameter. It was discovered on 4 November 1969 by Soviet astronomerNikolai Chernykh at theCrimean Astrophysical Observatory in Nauchnij on theCrimean peninsula.[1] In September 2008,European Space Agency's (ESA) spacecraftRosetta flew by Šteins, making it one of fewminor planets ever visited by a spacecraft. The brightE-type asteroid features23 named craters and has arotation period of 6.05 hours.[8] It was named for Soviet Latvian astronomerKārlis Šteins.[1]
Šteins is a non-family asteroid from the main belt'sbackground population.[3][4] It orbits the Sun in theinner asteroid belt at a distance of 2.0–2.7 Astronomical units (AU) once every 3 years and 8 months (1,327 days;semi-major axis of 2.36 AU). Its orbit has aneccentricity of 0.15 and aninclination of 10° with respect to theecliptic.[2] The body'sobservation arc begins with aprecovery, taken at thePalomar Observatory in November 1951, or 18 years prior to its official discovery observation.[1]
Thisminor planet was named in memory ofKārlis Šteins (1911–1983), aLatvian andSoviet astronomer. He was a long-time observatory director at theUniversity of Latvia in Riga and designed astronomical instruments. Šteins is known for his work on cometarycosmogony and the study ofEarth's rotation.[1] The official naming citation was published by theMinor Planet Center on 18 September 1986 (M.P.C. 11157).[14]
On 11 May 2012, IAU'sWorking Group for Planetary System Nomenclature announced a naming system for geographical features on Šteins.[15] Inspired by the asteroid'sgem-like shape, itscrater are given the English-language names of precious stones, with the largest being namedDiamond crater(see below).
Except for themontes ofMercury and thelunar maria (and proposed for2 Pallas and7 Iris), thecraters of Šteins are the only features in theSolar System whose names are not derived from proper nouns.[16] In addition, a distinct region on the asteroid has been named Chernykh Regio after the discoverer,Nikolai Chernykh.[17]
A study published in 2006 by astronomers at theEuropean Southern Observatory showed that Šteins is anE-type asteroid with a diameter of approximately 4.6 kilometers.[9] After the Rosetta flyby, the ESA described Šteins as a "diamond in the sky", as it has a wide body that tapers into a point. The wide section is dominated by the largeDiamond crater with a diameter of 2.1 kilometers, which surprised scientists, who were at first amazed the asteroid survived such an impact,[18] while later it turned out that the crater-to-body diameter ratio of 0.79 is in fact not abnormally large as it follows an already established trend.[19] Besides its irregular in shape, it does not have anymoons.[20]
According to the survey carried out by theNEOWISE mission ofNASA'sWide-field Infrared Survey Explorer and observations by theSpitzer Space Telescope, Šteins measures 5.16 and 4.92 kilometers in diameter and its surface has analbedo of 0.30 and 0.34, respectively.[6][7] Its overall Bond albedo is 0.24 ± 0.01.[21] In 2012, the photographs of Šteins taken byRosetta using stereophotoclinometry allowed scientists to determine that the asteroid's dimensions are6.83 × 5.70 × 4.42 kilometers, which equates to a mean diameter in volume of 5.26 km.[5] TheCollaborative Asteroid Lightcurve Link adopts an albedo of 0.34 and a diameter of 4.9 kilometers with anabsolute magnitude of 13.36.[8]
Studying the asteroid withRosetta spacecraft onboard OSIRIS cameras shortly before its flyby showed via alightcurve analysis that Šteins has arotation period of6.052±0.007 hours.[22][20] The results of the rotational lightcurve agree with ground-basedphotometric observations of Šteins with a period of 6.049 hours and a brightness amplitude between 0.18 and 0.31magnitude (U=3/3).[8][10][12][13][23][24][a]
Alightcurve inversion also modeled a concurring sidereal period of 6.04681 hours and determined aspin axis at (250.0°, −89.0°) inecliptic coordinates (λ, β). The modeling was done by compiling a set of 26 previously obtained visible lightcurves.[25]
On 5 September 2008, theRosetta space probe flew by Šteins at a distance of 800 km and a relatively slow speed of 8.6 km/s. Despite the short duration of this encounter (approximately 7 minutes in total), a great amount of data was obtained by the 15 scientific instruments operating on board the Rosetta spacecraft.[26] This was the first of two planned asteroid flybys performed by the probe, with the second being to the much larger21 Lutetia in 2010.[27] The timing of the flyby meant that the asteroid was illuminated by the Sun from the perspective of the spacecraft, making the transmitted images clear. TheEuropean Space Operations Centre streamed a press conference on Šteins later that day.[28]
Rosetta mission | ||
|---|---|---|
| Equipment | ||
| Targets |
| |
