682 Hagar

682 Hagar (prov. designation: A909 MA or 1909 HA) is an Eunomia asteroid 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.[1] The presumed S-type asteroid has a short rotation period of 4.9 hours and measures approximately 19 kilometers (12 miles) in diameter. Possibly inspired by the asteroid's provisional designation "1909 HA", it was named for the biblical woman Hagar.[3]

682 Hagar
Modelled shape of Hagar from its lightcurve
Discovery [1]
Discovered byA. Kopff
Discovery siteHeidelberg Obs.
Discovery date17 June 1909
Designations
(682) Hagar
Pronunciation/ˈheɪɡɑːr/[2]
Named after
Hagar (Biblical woman)[3]
A909 MA · 1943 GK
1953 VU3 · 1975 VO5
1909 HA
main-belt [1][4] · (middle)
Eunomia [5][6][7]
Orbital characteristics [4]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc110.96 yr (40,529 d)
Aphelion3.1105 AU
Perihelion2.1966 AU
2.6536 AU
Eccentricity0.1722
4.32 yr (1,579 d)
225.55°
0° 13m 40.8s / day
Inclination11.507°
190.78°
105.08°
Physical characteristics
Mean diameter
19±4 km[8]
4.8503±0.0001 h[8][lower-alpha 1]
  • (56.0°, −78.0°) (λ1/β1)[9]
  • (255.0°, −57.0°) (λ2/β2)[9]
0.057 (assumed)[8]

    Orbit and classification

    When applying the hierarchical clustering method to its proper orbital elements, Hagar is a core member of the Eunomia family (502),[5][6][7] a prominent family of stony S-type asteroids and the largest one in the intermediate main belt with more than 5,000 known members.[11]: 23  It orbits the Sun in the central main-belt at a distance of 2.2–3.1 AU once every 4 years and 4 months (1,579 days; semi-major axis of 2.65 AU). Its orbit has an eccentricity of 0.17 and an inclination of 12° with respect to the ecliptic.[4] 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.[1]

    Naming

    This minor planet was named after the biblical woman Hagar from the Book of Genesis. She was an Ancient Egyptian servant of Sarah and the mother of Abraham's firstborn, Ishmael. The asteroid's name may have been inspired by the two letters of its provisional designation, "1909 HA".[3] 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.[12]

    Physical characteristics

    Based on the overall spectral type of the Eunomia family,[11]: 23  Hagar is possibly a common, stony S-type asteroid.[10] However, observations by Pilcher (see below) found a V–R color index of 0.400±0.040, which rather suggest a low albedo of a carbonaceous C-type asteroid.[8]

    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 (G50) in Arizona. Analysis gave a well-defined, classically shaped bimodal lightcurve with a rotation period of (4.8503±0.0001) hours and a high brightness variation of 0.52±0.03 magnitude (U=3).[8][lower-alpha 1] At the same time, Alexander Kurtenkov at Sofia University, and a team of Bulgarian students obtained a concurring period of 4.854±0.011 hours with an amplitude of 0.49±0.03 magnitude (U=3).[13] In July 2017, French and Swiss astronomers René Roy and Raoul Behrend confirmed the period measuring a nearly identical rotation of (4.8516±0.0003) hours and an amplitude of 0.51±0.02 magnitude (U=3).[14]

    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 (4.850417±0.000001) and (4.85042±0.00005) 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.[15][16]

    Diameter and albedo

    American photometrist Frederick Pilcher also determined a diameter of 19±4 kilometers based on a visual absolute magnitude of 12.27±0.07, and an albedo of 0.057 derived from its measured V–R color index (see above).[8] The Collaborative Asteroid Lightcurve Link adopts Pilcher's albedo of 0.057 and derives a diameter of 19.57 kilometers.[10]

    Notes
    1. Lightcurve plot of (682) Hagar, by Frederick Pilcher (2013) at the Organ Mesa Observatory (G50) in Arizona. Rotation period 4.8503±0.0001 hours with a brightness amplitude of 0.52±0.03 mag. Quality code is 3. Summary figures at the LCDB and ASLC website.

    References
    1. "682 Hagar (A909 MA)". Minor Planet Center. Retrieved 21 July 2020.
    2. Noah Webster (1884) A Practical Dictionary of the English Language
    3. Schmadel, Lutz D. (2007). "(682) Hagar". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. pp. 66–67. doi:10.1007/978-3-540-29925-7_683. ISBN 978-3-540-00238-3.
    4. "JPL Small-Body Database Browser: 682 Hagar (A909 MA)" (2020-06-03 last obs.). Jet Propulsion Laboratory. Retrieved 21 July 2020.
    5. "Asteroid 682 Hagar – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 21 July 2020.
    6. "Asteroid 682 Hagar – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 21 July 2020.
    7. Zappalà, V.; Bendjoya, Ph.; Cellino, A.; Farinella, P.; Froeschle, C. (1997). "Asteroid Dynamical Families". NASA Planetary Data System: EAR-A-5-DDR-FAMILY-V4.1. Retrieved 20 July 2020. (PDS main page)
    8. Pilcher, Frederick; Franco, Lorenzo (January 2014). "Rotation Period and H-G Parameters of 682 Hagar" (PDF). Minor Planet Bulletin. 41 (1): 35–36. Bibcode:2014MPBu...41...35P. ISSN 1052-8091. Archived from the original (PDF) on 21 July 2020. Retrieved 21 July 2020.
    9. "Asteroid 682 Hagar". Small Bodies Data Ferret. Retrieved 21 July 2020.
    10. "LCDB Data for (682) Hagar". Asteroid Lightcurve Database (LCDB). Retrieved 21 July 2020.
    11. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131. S2CID 119280014.
    12. Schmadel, Lutz D. (2007). "(579) Sidonia". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. pp. 59–60. doi:10.1007/978-3-540-29925-7_580. ISBN 978-3-540-00238-3.
    13. Kurtenkov, Alexander; Teneva, Deana; Todorov, Lachezar; Stoyanov, Stanislav (January 2014). "Rotation Period Determination for 682 Hagar" (PDF). Minor Planet Bulletin. 41 (1): 36. Bibcode:2014MPBu...41...36K. ISSN 1052-8091. Archived from the original (PDF) on 21 July 2020. Retrieved 21 July 2020.
    14. Behrend, Raoul. "Asteroids and comets rotation curves – (682) Hagar". Geneva Observatory. Retrieved 21 July 2020.
    15. Ďurech, J.; Hanuš, J.; Oszkiewicz, D.; Vančo, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: A48. arXiv:1601.02909. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573. ISSN 0004-6361. S2CID 118427201.
    16. Hanus, J.; Durech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: 24. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. S2CID 119112278.
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