699 Hela

History and naming

Hela was discovered on 5 June 1910 in photographs taken by German astronomer Joseph Helffrich on 5–6 June at Heidelberg Observatory. It was reported in the journal Astronomische Nachrichten on 11 June under the old-style provisional designation 1910 KD. The asteroid was later named Hela, possibly after the Norse goddess of the dead Hel, ruler of the underworld.

Subsequent observations of Hela were conducted by Johann Palisa in Vienna on 10 and 14 June and 2, 4, and 5 July. Helffrich and Palisa's observations were unfavorably distributed, preventing the calculation of Hela's orbit. Nevertheless, its high eccentricity was already noticed by astronomers. In 1911, astronomer Adolf Berberich identified the lost asteroid 1902 KQ with Hela; by that time, Hela had been assigned the number (699). 1902 KQ was observed from Heidelberg Observatory on 21 November 1902, making these observations the earliest precoveries of Hela identified.

In 1925, the style of minor planet provisional designations was changed from a rotating system from AA to ZZ to one tied to half-months and days of the month. This system is currently in use, and was retroactively extended to minor planets discovered before 1925. Thus, Hela's designations for its official discovery and earliest precovery were changed from 1910 KD and 1902 KQ to 1910 LC and 1902 WE, respectively.

Orbit

Hela orbits the Sun with an average distance, or semi-major axis, of 2.61 astronomical units (AU), taking 4.23 years to complete one orbit. Due to its high orbital eccentricity of 0.41, its distance from the Sun varies from 3.69 AU at aphelion to 1.54 AU at perihelion, crossing the orbit of Mars. It has an orbital inclination of 15.29° with respect to the ecliptic plane.

Physical characteristics

With an absolute magnitude of 11.7, the asteroid is about 12–27 km in diameter. It is classified as a stony Sk or Sq-type asteroid in the SMASS taxonomy. Photometry data used to produce light curves provide a rotation period of . The lightcurve inversion method was used to build a shape model with a rounded form and an equatorial bulge.

Notes

References

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References

1. Noah Webster (1884) ''A Practical Dictionary of the English Language''