1204 Renzia, provisional designation , is a stony

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

and sizable

Mars-crosser A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and . Many databases, for i ...

on an eccentric orbit from the inner regions of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...

, approximately 10 kilometers in diameter. It was discovered by astronomer

Karl Reinmuth Karl Wilhelm Reinmuth (4 April 1892 in Heidelberg – 6 May 1979 in Heidelberg) was a German astronomer and a prolific discoverer of 395 minor planets. Scientific career From 1912 to 1957, Reinmuth was working as an astronomer at the Lande ...

at the

Heidelberg-Königstuhl State Observatory Heidelberg-Königstuhl State Observatory (german: Landessternwarte Heidelberg-Königstuhl) is a historic astronomical observatory located near the summit of the Königstuhl hill in the city of Heidelberg in Germany. The predecessor of the curre ...

in southwest Germany on 6 October 1931. The asteroid was named after German-Russian astronomer Franz Renz.

Orbit and classification

''Renzia'' is a

Mars-crossing asteroid A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers Minor planet designation, numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and ...

, a dynamically unstable group between the

main belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...

and the near-Earth populations, crossing the orbit of Mars at 1.666 AU. It orbits the Sun at a distance of 1.6–2.9 AU once every 3 years and 5 months (1,244 days). Its orbit has an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

of 0.29 and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 2 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic again ...

. The body's

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

begins at Heidelberg with its official discovery observation in 1931.

Impact probability

In the 1980s, British astronomer

Duncan Steel Duncan I. Steel is a British space scientist. He has discoverer of minor planets, discovered several minor planets and has written four popular science books. He is a member of the International Astronomical Union, which lists him as working a ...

calculated that ''Renzia'' has the third highest probability of impacting into

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

among a large sample of Mars-crossing asteroids. With a collision probability of 4.84 impacts per billion orbits, ''Renzia'' is only behind the asteroids (4.96) and 8303 Miyaji (5.08), which are both significantly smaller. He also calculated that such an impact event may occur every 300,000 years, for an assumed population of 10 thousand Mars-crossers larger than 1 kilometer producing

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...

s of at least 10 kilometers in diameter.

Physical characteristics

In the

SMASS classification An asteroid spectral type is assigned to asteroids based on their emission spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally differentiat ...

, ''Renzia'' is a common stony

S-type asteroid S-type asteroids are asteroids with a spectral type that is indicative of a siliceous (i.e. stony) mineralogical composition, hence the name. They have relatively high density. Approximately 17% of asteroids are of this type, making it the second ...

Lightcurves

In September 1982, a first rotational

lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

of ''Renzia'' was obtained from photometric observations at the

Table Mountain Observatory Table Mountain Observatory (TMO) is an astronomical observation facility operated by NASA's Jet Propulsion Laboratory (California Institute of Technology). It is located in Big Pines, California, in Angeles National Forest near Wrightwood, north- ...

in California. Lightcurve analysis gave a

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

of 7.885 hours with a brightness variation of 0.42

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

(). In February 2012, observations in the R-band by astronomers at the

Palomar Transient Factory The Palomar Transient Factory (PTF, obs. code: I41), was an astronomical survey using a wide-field survey camera designed to search for optical transient and variable sources such as variable stars, supernovae, asteroids and comets. The projec ...

gave an identical period with an amplitude of 0.49 magnitude (). Two 2016-studies also modeled the asteroid's lightcurve. They gave a concurring sidereal period of 7.88695 and 7.88697 hours. Each of the studies also determined two spin axis in

ecliptic coordinates The ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small Solar System bodi ...

(λ, β): (142.0°, −50.0°) and (305.0°, −45.0°), as well as (130.0°, −44.0°) and (312.0°, −51.0°).

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, ...

mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, ...

, ''Renzia'' measures 10.49 and 10.73 kilometers in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

of 0.254 and 0.222, respectively. The ''Collaborative Asteroid Lightcurve Link'' derives an albedo of 0.2103 and a diameter of 10.82 kilometers based on an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 12.14. With a diameter above 10 kilometers, ''Renzia'' is larger than most sizable

s such as 1065 Amundsenia (9.75 km), 1139 Atami (9.35 km),

1474 Beira 1474 Beira, provisional designation , is a bright carbonaceous asteroid and large Mars-crosser on an eccentric orbit from the asteroid belt, approximately 15 kilometers in diameter. It was discovered on 20 August 1935, by South African astronomer ...

(15 km), 1011 Laodamia (7.39 km), 1727 Mette (est 9 km), 1131 Porzia (7.13 km), 1235 Schorria (est. 9 km), 985 Rosina (8.18 km) 1310 Villigera (15.24 km), and 1468 Zomba (7 km); but still smaller than the largest members of this dynamical group, namely, 132 Aethra, 323 Brucia, 1508 Kemi, 2204 Lyyli and 512 Taurinensis, which are larger than 20 kilometers in diameter (in one or other given source).

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 after German-Russian astronomer Franz Robert Renz (1860–1942) also known as Franz Franzevich Renz, who worked at the

Dorpat Tartu is the second largest city in Estonia after the Northern Europe, Northern Europe, European country's political and financial capital, Tallinn. Tartu has a population of 91,407 (as of 2021). It is southeast of Tallinn and 245 kilometres ...

and

Pulkovo Pulkovo may refer to: *Pulkovo Heights marking the southern limit of Saint Petersburg, Russia *Pulkovo Airport serving Saint Petersburg, Russia *Pulkovo Aviation Enterprise, a former (until 2006) state airline based in Saint Petersburg, Russia *Pul ...

observatories. The official naming citation was mentioned in ''

The Names of the Minor Planets Paul Herget (January 30, 1908 – August 27, 1981) was an American astronomer and director of the Cincinnati Observatory, who established the Minor Planet Center after World War II. Career Herget taught astronomy at the University of Cincinna ...

'' by

Paul Herget Paul Herget (January 30, 1908 – August 27, 1981) was an American astronomer and director of the Cincinnati Observatory, who established the Minor Planet Center after World War II. Career Herget taught astronomy at the University of Cincinna ...

in 1955 ().

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend

– Minor Planet Center * * {{DEFAULTSORT:Renzia 001204 Discoveries by Karl Wilhelm Reinmuth Renzia 001204 19311006