699 Hela is a Mars crossing asteroid. It was discovered on 5 June 1910 at Heidelberg by German astronomer Joseph Helffrich, and may have been named after Hel, the Norse ruler of the underworld.[4] This asteroid is orbiting the Sun at a distance of 2.61 AU with a period of 4.22 years and an eccentricity of 0.41. The orbital plane is inclined at an angle of 15.3° to the plane of the ecliptic.[1]

699 Hela
699Hela (Lightcurve Inversion).png
Lightcurve-based 3D-model of Hela
Discovered byJ. Helffrich
Discovery siteHeidelberg
Discovery date5 June 1910
(699) Hela
1910 KD
Mars crosser[1]
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc113.38 yr (41,411 d)
Aphelion3.6831 AU (550.98 Gm)
Perihelion1.5414 AU (230.59 Gm)
2.6123 AU (390.79 Gm)
4.22 yr (1,542.1 d)
0° 14m 0.384s / day
Earth MOID0.62609 AU (93.662 Gm)
Mars MOID0.4063 AU (60.78 Gm)
Jupiter MOID2.10581 AU (315.025 Gm)
Physical characteristics
Dimensions12 - 27 km[3]
3.3962 h (0.14151 d)[1]

With an absolute magnitude of 11.7,[1] the asteroid is about 12–27 km in diameter.[3] It is classified as a stony Sk[5] or Sq-type[1] asteroid in the SMASS taxonomy. Photometry data used to produce light curves provide a rotation period of 3.39624±0.00006 h. The lightcurve inversion method was used to build a shape model with a rounded form and an equatorial bulge.[6]


  1. ^ a b c d e f g "JPL Small-Body Database Browser: 699 Hela (1910 KD)". Jet Propulsion Laboratory. Retrieved 7 May 2016.
  2. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  3. ^ a b "Absolute Magnitude (H)". NASA/JPL. Archived from the original on 2 March 2001. Retrieved 24 June 2014.
  4. ^ Schmadel, Lutz (2003), Dictionary of minor planet names, vol. 1, Springer, p. 68, ISBN 9783540002383.
  5. ^ Angeli, C. A.; Lazzaro, D. (August 2002), "Spectral properties of Mars-crossers and near-Earth objects. Results of the S3OS2 survey", Astronomy and Astrophysics, 391: 757–765, Bibcode:2002A&A...391..757A, doi:10.1051/0004-6361:20020834.
  6. ^ Alonso, E. Díez; et al. (April 2021), "Asteroids 4092 Tyr (Follow Up, Analysis, Preliminary Results) and 699 Hela (Spin-Shape Model)", Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, 48 (2): 136–139, Bibcode:2021MPBu...48..136A.

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