1016 Anitra, provisional designation , is a stony Florian

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 ...

and suspected asynchronous

binary system A binary system is a system of two astronomical bodies of the same kind that are comparable in size. Definitions vary, but typically require the center of mass to be located outside of either object. (See animated examples.) The most common ki ...

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 10 kilometers in diameter. It was discovered on 31 January 1924, 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 He ...

at the

Heidelberg-Königstuhl State Observatory Heidelberg-Königstuhl State Observatory () is a historic astronomical observatory located near the summit of the Königstuhl hill in the city of Heidelberg in Germany. It is operated by the ''Center for Astronomy (ZAH)'' at the University of He ...

in southwest Germany. The asteroid was likely named after the fictional character Anitra from

Henrik Ibsen Henrik Johan Ibsen (; ; 20 March 1828 – 23 May 1906) was a Norwegian playwright, poet and actor. Ibsen is considered the world's pre-eminent dramatist of the 19th century and is often referred to as "the father of modern drama." He pioneered ...

's drama ''

Peer Gynt ''Peer Gynt'' (, ) is a five-Act (drama), act play in verse written in 1867 by the Norwegian dramatist Henrik Ibsen. It is one of Ibsen's best known and most widely performed plays. ''Peer Gynt'' chronicles the journey of its title character fr ...

''.

Orbit and classification

''Anitra'' is a member of the

Flora family The Flora family (''adj. Florian''; ; also known as the Ariadne family) is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approx ...

(), 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 ...

and the largest family of stony asteroids in the main-belt. It orbits the Sun in the inner main-belt at a distance of 1.9–2.5 AU once every 3 years and 4 months (1,208 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-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.13 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 reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 6 ° 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 asteroid'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, 12 days after to its official discovery observation.

Physical characteristics

In the

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

, ''Anitra'' is a common, stony

S-type asteroid S-type (stony-type or silicaceous-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 ...

Rotation period

In November 2015, a rotational

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 ...

of ''Anitra'' was obtained from photometric observations by an international collaborations of astronomers who combined their observational results. Lightcurve analysis gave a

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

of 5.92951 hours with a brightness amplitude of 0.30

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 ...

().

Binary system

''Anitra'' is a suspected asynchronous

binary asteroid A binary asteroid is a system of two asteroids orbiting their common barycenter. The binary nature of 243 Ida was discovered when the Galileo spacecraft flew by the asteroid in 1993. Since then numerous binary asteroids and several triple a ...

, a system with a fairly large separation, for which tidal forces have been insufficient to synchronize the periods within the system's lifetime. The likely

minor-planet moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

has a rotation period of 2.609 hours and is thought to orbit its primary every 240 hours. The results, however, are still tentative. More than 100 known binaries from the asteroid belt have already been discovered.

Diameter and albedo

According to the survey carried out by the

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...

mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

, ''Anitra'' measures 9.539 and 10.302 kilometers in diameter and its surface has an

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

of 0.2728 and 0.308, respectively. The ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for stony S-type asteroids of 0.20 and calculates a diameter of 12.97 kilometers based on an absolute magnitude of 11.8.

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 probably named after the Arabian dancer Anitra, daughter of a Bedouin chief in

's drama ''

'', a five-act play in verse. The music was composed by

Edvard Grieg Edvard Hagerup Grieg ( , ; 15 June 18434 September 1907) was a Norwegian composer and pianist. He is widely considered one of the leading Romantic music, Romantic era composers, and his music is part of the standard classical repertoire worldwid ...

who named one piece "Anitra's Dance". The minor planets and are named after Grieg and Ibsen, respectively. The official naming citation is based on research by

Lutz Schmadel Lutz Dieter Schmadel (2 July 1942, in Berlin – 21 October 2016) was a German astronomer and a prolific discoverer of asteroids, who worked at the Astronomisches Rechen-Institut (ARI) of the University of Heidelberg. His special interest was th ...

and feedback from astronomers R. Bremer and I. van Houten-Groeneveld.

Orbit and classification

Physical characteristics

Rotation period

Binary system

Diameter and albedo

Naming

Notes

References

External links