1131 Porzia, 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 from the innermost regions of the asteroid belt, approximately 7 kilometers in diameter. It was discovered on 10 September 1929, by German 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 Observatory Heidelberg (; Palatine German: ') is a city in the German state of Baden-Württemberg, situated on the river Neckar in south-west Germany. As of the 2016 census, its population was 159,914, of which roughly a quarter consisted of students. ...

in southwest Germany. The asteroid was named after Porcia wife of Brutus, who assassinated Julius Caesar.

Orbit and classification

''Porzia'' is a Mars-crossing asteroid, a dynamically unstable group between the main belt and the near-Earth populations, crossing the orbit of

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 ...

at 1.666 AU. It orbits the Sun at a distance of 1.6–2.9 AU once every 3 years and 4 months (1,215 days). Its orbit has an eccentricity 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 3 ° with respect to the ecliptic. 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, 19 days after its official discovery observation.

Physical characteristics

In the SMASS taxonomy, ''Porzia'' 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

Two rotational lightcurves of ''Porzia'' were obtained by Vladimir Benishek at Belgrade Observatory shortly before its opposition in November 2009, and by French amateur astronomer René Roy in December 2012. Lightcurve analysis gave a well defined

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 4.6584 and 4.6601 hours with a brightness variation of 0.15 and 0.19 magnitude, respectively (). The results supersede photometric observations taken by Polish astronomer

Wiesław Wiśniewski :"Wiesław" is sometimes transliterated as "Wieslaw", in the absence of ''L with stroke.'' Wiesław () is a Polish masculine given name, of Slavonic origin, meaning "great glory" or "all glory". It is the shortened, more common, form of the person ...

in January 1990, which rendered a lightcurve with a period hours and an amplitude of 0.23 magnitude ().

Diameter and albedo

According to the survey carried out by 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, ...

and its subsequent NEOWISE mission, ''Porzia'' measures 6.53 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 0.287, while the ''Collaborative Asteroid Lightcurve Link'' assumes a standard

for stony asteroids of 0.20 and calculates a diameter of 7.13 kilometers with 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 13.10. This makes ''Porzia'' one of the larger mid-sized Mars-crossing asteroids comparable with 1065 Amundsenia (9.75 km), 1139 Atami (9.35 km), 1474 Beira (8.73 km), 1011 Laodamia (7.5 km), 1727 Mette (est. 9 km), 1235 Schorria (est. 9 km), 985 Rosina (8.18 km), 1310 Villigera (15.24 km) and

1468 Zomba 1468 Zomba, provisional designation , is a stony asteroid and large Mars-crosser near the innermost regions of the asteroid belt, approximately 7 kilometers in diameter. Discovered by Cyril Jackson at Johannesburg Observatory in 1938, the asteroi ...

(7 km), but far smaller than the largest members of this dynamical group, namely,

132 Aethra Aethra (minor planet designation: 132 Aethra) is a metallic asteroid and Mars-crosser on an eccentric orbit from the asteroid belt. It measures approximately 40 kilometers in diameter. It was discovered by James Craig Watson in 1873 and is the ...

, 323 Brucia, 1508 Kemi, 2204 Lyyli and 512 Taurinensis, which are all larger than 20 kilometers in diameter.

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 the wife of Brutus, Porcia Catonis, who kills herself at news of her husband's death in Shakespeare's play ''

Julius Caesar Gaius Julius Caesar (; ; 12 July 100 BC – 15 March 44 BC), was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in a civil war, and ...

''. The official naming citation was also published by Paul Herget in '' The Names of the Minor Planets'' in 1955 ().

References

External links

Photometry of Asteroids at The Belgrade Astronomical Observatory
Vladimir Benishek's Page
Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend

– Minor Planet Center * * {{DEFAULTSORT:Porzia 001131 Discoveries by Karl Wilhelm Reinmuth Named minor planets 001131 19290910