1474 Beira, provisional designation , is a bright carbonaceous

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 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 Cyril Jackson at the

Union Observatory Union Observatory also known as Johannesburg Observatory ( 078) is a defunct astronomical observatory in Johannesburg, South Africa that was operated between 1903 and 1971. It is located on Observatory Ridge, the city's highest point at 1,808 met ...

in Johannesburg. The asteroid was named after the port city of Beira in Mozambique.

Orbit and classification

''Beira'' is a Mars-crossing asteroid, a dynamically unstable group between the main belt and the near-Earth populations, crossing the orbit of Mars at 1.666 AU. It orbits the Sun at a distance of 1.4–4.1 AU once every 4 years and 6 months (1,650 days). Its orbit has a high eccentricity of 0.49 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 27 ° 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 with its official discovery observation at Johannesburg in 1935.

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 ...

, ''Beira'' is a bright carbonaceous

B-type asteroid B-type asteroids are a relatively uncommon type of carbonaceous asteroid, falling into the wider C-group; the 'B' indicates these objects are spectrally blue. In the asteroid population, B-class objects can be found in the outer asteroid belt, an ...

, while in the Tholen classification its spectral type is ambiguous, closest to an F-type and somewhat similar to that of an X-type asteroid.

Rotation period

Three rotational lightcurves of ''Beira'' were obtained from photometric observations. 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 4.184 hours with a brightness amplitude between 0.15 and 0.24 magnitude ().

Diameter and albedo

According to the survey carried out by the NEOWISE 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, ...

, ''Beira'' measures between 14.9 and 15.46 kilometers in diameter and its surface has a low

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 ...

between 0.06 and 0.07. Conversely, the ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for stony asteroids of 0.20 and consequently calculates a smaller diameter of 8.73 kilometers using 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 12.66. With a diameter close to 15 kilometers, ''Beira'' is larger than most sizeable Mars-crossing asteroids such as 1065 Amundsenia (9.75 km),

1139 Atami 1139 Atami, provisional designation , is a stony asteroid and sizable Mars-crosser, as well as a synchronous binary system near the innermost region of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 1 December 1929 ...

(9.35 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 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 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 the port city of Beira in Mozambique. The official was published by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

in April 1953 ().

Notes

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:Beira 001474 Discoveries by Cyril Jackson (astronomer) Named minor planets 001474 001474 19350820