Isarawith the stress on the 'i' (

minor planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a leading number (catalog or ...

: 364 Isara) is a stony Florian

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. ...

from the inner regions of the asteroid belt, approximately 27 kilometers in diameter. It was discovered on 19 March 1893, by French astronomer Auguste Charlois at the

Nice Observatory The Nice Observatory (french: Observatoire de Nice) is an astronomical observatory located in Nice, France on the summit of Mount Gros. The observatory was founded in 1879, by the banker Raphaël Bischoffsheim. The architect was Charles Garnier, ...

in southeast France. The asteroid was named after the Isère River in France.

Orbit and classification

''Isara'' is a member of the Flora family (), a giant

asteroid family An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An a ...

and the largest family of stony asteroids in the main-belt. It orbits the Sun in the

inner Interior may refer to: Arts and media * ''Interior'' (Degas) (also known as ''The Rape''), painting by Edgar Degas * ''Interior'' (play), 1895 play by Belgian playwright Maurice Maeterlinck * ''The Interior'' (novel), by Lisa See * Interior de ...

main-belt at a distance of 1.9–2.6 AU once every 3 years and 4 months (1,209 days). Its orbit has an eccentricity of 0.15 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 6 ° 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 Vienna Observatory in April 1900, seven years after to its official discovery observation at Nice.

Physical characteristics

In the Tholen classification, ''Isara'' 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 ...

, which agrees with the overall spectral type of the Flora family.

Rotation period

In 2009, photometric observations of ''Isara'' were made by American astronomer Brian Warner at the Palmer Divide Observatory () in Colorado, by amateur astronomer René Roy at Blauvac Observatory () in France, and by a group of Polish astronomers led by Agnieszka Kryszczyńska of the

Polish Astronomical Society The Polish Astronomical Society (Polish: ''Polskie Towarzystwo Astronomiczne, PTA'') is science society in Poland, founded in 1923, with headquarters in Warsaw. Members of PTA are professional astronomers. Purpose of the association is promoting ...

. The resulting asymmetrical lightcurves showed a synodic

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 ...

between 9.151 and 9.157 hours with a brightness variation between 0.30 and 0.40 in magnitude (). The results agree with the first rotational lightcurve was already obtained in the 1960s ().

Spin axis

In 2013, an international study modeled a lightcurve with a concurring period of 9.15751 hours and found two

spin axis Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rota ...

of (282.0°, 44.0°) and (86.0°, 42.0°) in ecliptic coordinates (λ, β) ().

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite

IRAS The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...

, the Japanese Akari satellite and 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, ...

, ''Isara'' measures between 25.901 and 35.209 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 ...

between 0.1625 and 0.300. The ''Collaborative Asteroid Lightcurve Link'' adopt the results obtained by IRAS, that is, an albedo of 0.2566 and a diameter of 27.99 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 9.86.

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 Isère River in south eastern France. ("Isara" is an early name for this river.) The official naming citation was mentioned in '' The Names of the Minor Planets'' by Paul Herget in 1955 ().

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:Isara 000364 Discoveries by Auguste Charlois Named minor planets 000364 18930319