2867 Šteins
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2867 Šteins (provisional designation ) is an irregular, diamond-shaped background
asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
from the inner regions of the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...
, approximately in diameter. It was discovered on 4 November 1969 by Soviet astronomer Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnij on the
Crimea Crimea ( ) is a peninsula in Eastern Europe, on the northern coast of the Black Sea, almost entirely surrounded by the Black Sea and the smaller Sea of Azov. The Isthmus of Perekop connects the peninsula to Kherson Oblast in mainland Ukrain ...
n peninsula. In September 2008, ESA's spacecraft '' Rosetta'' flew by Šteins, making it one of few minor planets ever visited by a spacecraft. The bright E-type asteroid features 23 named craters and has a rotation period of 6.05 hours. It was named for Soviet Latvian astronomer Kārlis Šteins.


Orbit and classification

Šteins is a non-
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
asteroid from the main belt's background population. It orbits the Sun in the inner asteroid belt at a distance of 2.0–2.7  AU once every 3 years and 8 months (1,327 days; semi-major axis of 2.36 AU). Its orbit has an eccentricity of 0.15 and an inclination of 10 ° with respect to the
ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...
. The body's observation arc begins with a precovery, taken at the Palomar Observatory in November 1951, or 18 years prior to its official discovery observation.


Naming

This
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
was named in memory of Kārlis Šteins (1911–1983), a
Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...
n and
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
astronomer. He was a long-time observatory director at the University of Latvia in Riga and designed astronomical instruments. Šteins is known for his work on cometary cosmogony and the study of
Earth's rotation Earth's rotation or Earth's spin is the rotation of planet Earth around its own Rotation around a fixed axis, axis, as well as changes in the orientation (geometry), orientation of the rotation axis in space. Earth rotates eastward, in progra ...
. The official naming citation was published by the Minor Planet Center on 18 September 1986 ().


Features on Šteins

On 11 May 2012, IAU's Working Group for Planetary System Nomenclature announced a naming system for geographical features on Šteins. Inspired by the asteroid's gem-like shape, its crater are given the English-language names of precious stones, with the largest being named Diamond crater ''(see below)''. Except for the montes of Mercury and the lunar maria (and proposed for 2 Pallas and 7 Iris), the craters of Šteins are the only features in the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
whose names are not derived from proper nouns. In addition, a distinct region on the asteroid has been named Chernykh Regio after the discoverer, Nikolai Chernykh.


Physical characteristics

A study published in 2006 by astronomers at the European Southern Observatory showed that Šteins is an E-type asteroid with a diameter of approximately 4.6 kilometers. 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 large Diamond crater with a diameter of 2.1 kilometers, which surprised scientists, who were at first amazed the asteroid survived such an impact, 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. Besides its irregular in shape, it does not have any
moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
s.


Diameter and albedo

According to the survey carried out by the NEOWISE mission of
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
's Wide-field Infrared Survey Explorer and observations by the Spitzer Space Telescope, Šteins measures 5.16 and 4.92 kilometers in diameter and its surface has an albedo of 0.30 and 0.34, respectively. Its overall Bond albedo is 0.24 ± 0.01. In 2012, the photographs of Šteins taken by ''Rosetta'' using stereophotoclinometry allowed scientists to determine that the asteroid's dimensions are kilometers, which equates to a mean diameter in volume of 5.26 km. (Asteroid was later named for the scientist using this 3D-method.) The ''Collaborative Asteroid Lightcurve Link'' adopts an albedo of 0.34 and a diameter of 4.9 kilometers with an absolute magnitude of 13.36.


Lightcurves and poles

Studying the asteroid with Rosetta space probe onboard OSIRIS cameras shortly before its flyby showed via a
lightcurve In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...
analysis that Šteins has a rotation period of hours. The results of the rotational lightcurve agree with ground-based photometric observations of Šteins with a period of 6.049 hours and a brightness amplitude between 0.18 and 0.31 magnitude (). A lightcurve inversion also modeled a concurring sidereal period of 6.04681 hours and determined a spin axis at (250.0°, −89.0°) in ecliptic coordinates (λ, β). The modeling was done by compiling a set of 26 previously obtained visible lightcurves.


Exploration


''Rosetta'' flyby

On 5 September 2008, the Rosetta 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. This was the first of two planned asteroid flybys performed by the probe, the second being to the much larger 21 Lutetia in 2010. The timing of the fly-by meant that the asteroid was illuminated by the sun from the perspective of the spacecraft, making the transmitted images clear. The European Space Operations Centre streamed a press conference on Šteins later that day.


See also

* List of craters on minor planets * List of minor planets and comets visited by spacecraft


Notes


References


External links


Steins: A diamond in the Sky
images, ESA

– Observatoire de Genève, Raoul Behrend
Rosetta's OSIRIS cameras reveal the nature of asteroid Steins
ESA, January 2010
Asteroid Lightcurve Database (LCDB)
query form


Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Steins 19691104 002867 Discoveries by Nikolai Chernykh 20080905 Named minor planets 2867 Steins