1251 Hedera

1251 Hedera (prov. designation: 1933 BE) is a background asteroid from the central regions of the asteroid belt, approximately 13 kilometers (8 miles) in diameter. It was discovered on 25 January 1933, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany.[16] The asteroid was named for the climbing plant Hedera, commonly known as "ivy".[3]

1251 Hedera
Modelled shape of Hedera from its lightcurve
Discovery[1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date25 January 1933
Designations
(1251) Hedera
Pronunciation/ˈhɛdərə/[2]
Named after
Hedera (a.k.a. "Ivy")[3]
1933 BE · 1929 CD1
1931 TJ2 · 1975 NW1
A907 GD · A915 CA
main-belt[1][4] · (middle)
background[5]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc102.80 yr (37,548 days)
Aphelion3.1452 AU
Perihelion2.2884 AU
2.7168 AU
Eccentricity0.1577
4.48 yr (1,636 days)
55.862°
0° 13m 12.36s / day
Inclination6.0489°
140.65°
217.52°
Physical characteristics
Mean diameter
13.239±0.150 km[6][7]
44.22 km (calculated)[4]
15.015±0.010 h[8]
19.9000±0.0002 h[9]
19.9020±0.0001 h[10]
19.9020±0.0002 h[11]
19.915±0.005 h[12]
19.915±0.007 h[12]
19.985±0.002 h[13]
0.057 (assumed)[4]
0.636±0.050[6][7]
Tholen = E[1]
SMASS = X[1]
E[7][14] · C(SDSS-MFB)[4]
B–V = 0.689[1]
U–B = 0.233[1]
10.5[1][4][7] · 10.67±0.28[15]

    Orbit and classification

    Hedera is a non-family asteroid from the main belt's background population.[5] It orbits the Sun in the central asteroid belt at a distance of 2.3–3.1 AU once every 4 years and 6 months (1,636 days; semi-major axis of 2.72 AU). Its orbit has an eccentricity of 0.16 and an inclination of 6° with respect to the ecliptic.[1] The asteroid was first observed as A907 GD at Heidelberg in April 1907. The body's observation arc begins at Heidelberg, the night after its official discovery observation.[16]

    Naming

    This minor planet was named after the evergreen woody plant Hedera ("ivy") a genus of climbing or ground-creeping woody plants in the aralia family (ivy family). The naming was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 115).[3]

    Reinmuth's flowers

    Due to his many discoveries, Karl Reinmuth submitted a large list of 66 newly named asteroids in the early 1930s. The list covered his discoveries with numbers between (1009) and (1200). This list also contained a sequence of 28 asteroids, starting with 1054 Forsytia, that were all named after plants, in particular flowering plants (also see list of minor planets named after animals and plants).[17]

    Physical characteristics

    Hedera is an E-type and X-type asteroid in the Tholen and SMASS classification, respectively.[1]

    Rotation period

    Several rotational lightcurves of Hedera have been obtained from photometric observations since 2007.[8][9][12][13] Best-rated lightcurve by Julian Oey at Kingsgrove and Leura observatories, Australia, gave a rotation period of 19.9000 hours with a consolidated brightness amplitude between 0.41 and 0.61 magnitude (U=3-).[4][9]

    Spin axis

    Modeled photometric data from the Lowell Photometric Database (LPD) and the robotic BlueEye600 Observatory, gave a concurring period of 19.9020 hours,[10][11] Both studies determined two spin axes of (124.0°, −70.0°) and (266.0°, −62.0°), as well as (271.0°, −53.0°) and (115.0°, −62.0°) in ecliptic coordinates (λ, β).[10][11]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Hedera measures 13.239 kilometers in diameter and its surface has an albedo of 0.636.[6][7]

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and consequently calculates a larger diameter of 44.22 kilometers based on an absolute magnitude of 10.50.[4]

    References
    1. "JPL Small-Body Database Browser: 1251 Hedera (1933 BE)" (2017-11-24 last obs.). Jet Propulsion Laboratory. Retrieved 31 December 2017.
    2. "hederal". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
    3. Schmadel, Lutz D. (2003). "(1251) Hedera". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 104. doi:10.1007/978-3-540-29925-7_1252. ISBN 978-3-540-00238-3.
    4. "LCDB Data for (1251) Hedera". Asteroid Lightcurve Database (LCDB). Retrieved 31 December 2017.
    5. "Asteroid 1251 Hedera – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    6. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.{{cite journal}}: CS1 maint: multiple names: authors list (link)
    7. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    8. Shevchenko, V. G.; Krugly, Yu. N.; Chiorny, V. G.; Belskaya, I. N.; Gaftonyuk, N. M. (August 2003). "Rotation and photometric properties of E-type asteroids". Planetary and Space Science. 51 (9–10): 525–532. Bibcode:2003P&SS...51..525S. doi:10.1016/S0032-0633(03)00076-X.
    9. Oey, Julian (September 2008). "Lightcurve Analysis of Asteroids from the Kingsgrove and Leura Observatories in the 2nd Half of 2007" (PDF). Minor Planet Bulletin. 35 (3): 132–135. Bibcode:2008MPBu...35..132O. ISSN 1052-8091.
    10. Durech, J.; Hanus, J.; Oszkiewicz, D.; Vanco, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: 6. arXiv:1601.02909. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573.
    11. Durech, Josef; Hanus, Josef; Broz, Miroslav; Lehky, Martin; Behrend, Raoul; Antonini, Pierre; et al. (July 2017). "Shape models of asteroids based on lightcurve observations with BlueEye600 robotic observatory". Icarus. 304: 101–109. arXiv:1707.03637. Bibcode:2018Icar..304..101D. doi:10.1016/j.icarus.2017.07.005.
    12. Behrend, Raoul. "Asteroids and comets rotation curves – (1251) Hedera". Geneva Observatory. Retrieved 31 December 2017.
    13. Chiorny, V. G.; Shevchenko, V. G.; Krugly, Yu. N.; Velichko, F. P.; Gaftonyuk, N. M. (May 2007). "Photometry of asteroids: Lightcurves of 24 asteroids obtained in 1993 2005". Planetary and Space Science. 55 (7–8): 986–997. Bibcode:2007P&SS...55..986C. doi:10.1016/j.pss.2007.01.001.
    14. Belskaya, I. N.; Fornasier, S.; Tozzi, G. P.; Gil-Hutton, R.; Cellino, A.; Antonyuk, K.; et al. (March 2017). "Refining the asteroid taxonomy by polarimetric observations". Icarus. 284: 30–42. Bibcode:2017Icar..284...30B. doi:10.1016/j.icarus.2016.11.003.
    15. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
    16. "1251 Hedera (1933 BE)". Minor Planet Center. Retrieved 31 December 2017.
    17. Schmadel, Lutz D. (2007). "(1054) Forsytia". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 90. doi:10.1007/978-3-540-29925-7_1055. ISBN 978-3-540-00238-3.
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