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699 Hela
	Lightcurve-based 3D-model of Hela
Discovery
Discovered by	J. Helffrich
Discovery site	Heidelberg
Discovery date	5 June 1910
Designations
MPC designation	(699) Hela
Pronunciation	/ˈhiːlə/
Alternative designations	1910 KD
Minor planet category	Mars crosser
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	113.38 yr (41,411 d)
Aphelion	3.6831 AU (550.98 Gm)
Perihelion	1.5414 AU (230.59 Gm)
Semi-major axis	2.6123 AU (390.79 Gm)
Eccentricity	0.40995
Orbital period (sidereal)	4.22 yr (1,542.1 d)
Mean anomaly	3.93957°
Mean motion	0° 14m 0.384s / day
Inclination	15.297°
Longitude of ascending node	242.548°
Argument of perihelion	91.479°
Earth MOID	0.62609 AU (93.662 Gm)
Mars MOID	0.4063 AU (60.78 Gm)
Jupiter MOID	2.10581 AU (315.025 Gm)
TJupiter	3.239
Physical characteristics
Dimensions	12 - 27 km
Synodic rotation period	3.3962 h (0.14151 d)
Absolute magnitude (H)	11.72

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.^[2]

With an absolute magnitude of 11.7,^[2] the asteroid is about 12–27 km in diameter.^[3] It is classified as a stony Sk^[5] or Sq-type^[2] 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]

References

^ Noah Webster (1884) A Practical Dictionary of the English Language
^ ^a ^b ^c ^d ^e ^f ^g "JPL Small-Body Database Browser: 699 Hela (1910 KD)". Jet Propulsion Laboratory. Retrieved 7 May 2016.
^ ^a ^b "Absolute Magnitude (H)". NASA/JPL. Archived from the original on 2 March 2001. Retrieved 24 June 2014.
^ Schmadel, Lutz (2003), Dictionary of minor planet names, vol. 1, Springer, p. 68, ISBN 9783540002383.
^ 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.
^ 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.

External links

Lightcurve plot of 699 Hela, Palmer Divide Observatory, B. D. Warner (1999)
Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
Dictionary of Minor Planet Names, Google books
Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
699 Hela at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
699 Hela at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

This Mars-crosser asteroid-related article is a stub. You can help Wikipedia by expanding it.

[1] Noah Webster (1884) A Practical Dictionary of the English Language

[jpldata-2] ^ ^a ^b ^c ^d ^e ^f ^g "JPL Small-Body Database Browser: 699 Hela (1910 KD)". Jet Propulsion Laboratory. Retrieved 7 May 2016.

[h-3] "Absolute Magnitude (H)". NASA/JPL. Archived from the original on 2 March 2001. Retrieved 24 June 2014.

[Schmadel2003-4] Schmadel, Lutz (2003), Dictionary of minor planet names, vol. 1, Springer, p. 68, ISBN 9783540002383.

[Angeli_Lazzaro_2002-5] 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.

[Alonso_et_al_2021-6] 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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