682 Hagar ('' prov. designation:'' ''or'' ) is an

Eunomia asteroid The Eunomia or Eunomian family () is a large asteroid family of S-type asteroids named after the asteroid 15 Eunomia. It is the most prominent family in the intermediate asteroid belt and the 6th-largest family with nearly six thousand known members ...

from the central regions of the asteroid belt. It was discovered on 17 June 1909, by German astronomer August Kopff at the Heidelberg-Königstuhl State Observatory. The presumed S-type asteroid has a short

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 4.9 hours and measures approximately in diameter. Possibly inspired by the asteroid's provisional designation "1909 HA", it was named for the biblical woman Hagar.

Orbit and classification

When applying the hierarchical clustering method to its proper orbital elements, ''Hagar'' is a core member of the Eunomia family (), a prominent family of stony S-type asteroids and the largest one in the intermediate main belt with more than 5,000 known members. It orbits the Sun in the

central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

main-belt at a distance of 2.2–3.1 AU once every 4 years and 4 months (1,579 days;

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

of 2.65 AU). Its orbit has an eccentricity of 0.17 and an inclination of 12 ° with respect to the ecliptic. The body's observation arc begins at Vienna Observatory on 28 June 1909, just eleven nights after prior to its official discovery observation by August Kopff at Heidelberg.

Naming

This minor planet was named after the biblical woman Hagar from the Book of Genesis. She was an Ancient Egyptian servant of

Sarah Sarah (born Sarai) is a biblical matriarch and prophetess, a major figure in Abrahamic religions. While different Abrahamic faiths portray her differently, Judaism, Christianity, and Islam all depict her character similarly, as that of a piou ...

and the mother of Abraham's firstborn,

Ishmael Ishmael ''Ismaḗl''; Classical/Qur'anic Arabic: إِسْمَٰعِيْل; Modern Standard Arabic: إِسْمَاعِيْل ''ʾIsmāʿīl''; la, Ismael was the first son of Abraham, the common patriarch of the Abrahamic religions; and is cons ...

. The asteroid's name may have been inspired by the two letters of its provisional designation, "1909 HA". It is also speculated that the name comes from a list created in 1913 by the Astronomisches Rechen-Institut (ARI) containing suggestions of female names from history and mythology for the naming of minor planets ( ''AN'' 196, 137). At the time, the naming process was not well developed and the ARI feared inconsistencies and potential confusion. The list was sent to several German astronomers, including Kopff, with the invitation to name all of their made discoveries up to number 700.

Physical characteristics

Based on the overall spectral type of the Eunomia family, ''Hagar'' is possibly a common, stony S-type asteroid. However, observations by Pilcher ''(see below)'' found a V–R color index of , which rather suggest a low albedo of a carbonaceous C-type asteroid.

Rotation period

In August 2013, a rotational lightcurve of ''Hagar'' was obtained from nine nights of photometric observations by Frederick Pilcher at the Organ Mesa Observatory in Arizona. Analysis gave a well-defined, classically shaped bimodal lightcurve with a

of () hours and a high brightness variation of magnitude (). At the same time, Alexander Kurtenkov at Sofia University, and a team of Bulgarian students obtained a concurring period of hours with an amplitude of magnitude (). In July 2017, French and Swiss astronomers René Roy and Raoul Behrend confirmed the period measuring a nearly identical rotation of () hours and an amplitude of magnitude ().

Poles

Two lightcurves, published in 2016, using modeled photometric data from the Lowell Photometric Database (LPD) and other sources, gave a concurring sidereal period of () and () hours, respectively. Each modeled lightcurve also determined two spin axes of (93.0°, −71.0°) and (277.0°, −35.0°), as well as (56.0°, −78.0°) and (255.0°, −57.0°) in ecliptic coordinates (λ, β), respectively.

Diameter and albedo

American photometrist Frederick Pilcher also determined a diameter of kilometers based on a visual absolute magnitude of , and an albedo of 0.057 derived from its measured V–R color index ''(see above)''. The ''Collaborative Asteroid Lightcurve Link'' adopts Pilcher's albedo of 0.057 and derives a diameter of 19.57 kilometers.

Notes

References

External links

Lightcurve Database Query
(LCDB), at ''www.minorplanet.info''
Dictionary of Minor Planet Names
Google books

– '' Geneva Observatory'', Raoul Behrend
Discovery Circumstances: Numbered Minor Planets (1)-(5000)
– Minor Planet Center * * {{DEFAULTSORT:Hagar 000682 Discoveries by August Kopff Named minor planets 19090617 Hagar