(127) Johanna

127 Johanna
127Johanna (Lightcurve Inversion).png
A three-dimensional model of 127 Johanna based on its light curve.
Discovered byPaul Henry and Prosper Henry
Discovery date5 November 1872
(127) Johanna
Named after
Joan of Arc
Main belt
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc98.53 yr (35989 d)
Aphelion2.94 AU (439.95 Gm)
Perihelion2.57 AU (384.67 Gm)
2.76 AU (412.31 Gm)
4.58 yr (1,671.3 d)
17.92 km/s
0° 12m 55.44s / day
Earth MOID1.60 AU (239.57 Gm)
Jupiter MOID2.11 AU (315.95 Gm)
Physical characteristics
116.14±3.93 km[3]
Mass(3.08 ± 1.35) × 1018 kg[3]
Mean density
3.75±1.68 g/cm3[3]
12.7988 h (0.53328 d)[2][4]
Temperature~168 K
CX[6] (Tholen)
Ch[6] (Bus)
8.6,[2] 8.30[5]

Johanna (minor planet designation: 127 Johanna) is a large, dark main-belt asteroid that was discovered by French astronomers Paul Henry and Prosper Henry on 5 November 1872, and is believed to be named after Joan of Arc.[7] It is classified as a CX-type asteroid, indicating the spectrum shows properties of both a carbonaceous C-type asteroid and a metallic X-type asteroid.[6]

A photoelectric study was performed of this minor planet in 1991 at the Konkoly Observatory in Hungary. The resulting light curve showed a synodic rotation period of 6.94 ± 0.29 hours with a brightness variation of 0.2 in magnitude. It was estimated to have an absolute magnitude of 8.459 ± 0.013 with a diameter of 96–118 km and an albedo of 0.06–0.04.[8]

Infrared observations made in 1982 at Konkoly showed a rapid variation that seemed to suggest a shorter rotation period of 1.5 hours; one of the fastest known at the time. However, an irregular shape was suggested as an alternative cause of the rapid variation.[9] The present day established rotation period of this object is 12.7988 hours.[4]

During 2001, 127 Johanna was observed by radar from the Arecibo Observatory. The return signal matched an effective diameter of 117 ± 21 km.[6] A larger diameter value of 123.41 ± 4.07 km was obtained from the Midcourse Space Experiment observations, with an albedo of 0.0557 ± 0.0039.[5] A 2012 study gave a refined diameter estimate of 116.14 ± 3.93 km.[3]


  1. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  2. ^ a b c d Yeomans, Donald K., "127 Johanna", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
  3. ^ a b c d Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
  4. ^ a b Behrend, Raoul, Courbes de rotation d'astéroïdes et de comètes (in French), Observatoire de Genève, retrieved 29 March 2013
  5. ^ a b c Tedesco, Edward F.; et al. (July 2002), "The Midcourse Space Experiment Infrared Minor Planet Survey", The Astronomical Journal, vol. 124, no. 124, pp. 583–591, Bibcode:2002AJ....124..583T, doi:10.1086/340960.
  6. ^ a b c d Magri, Christopher; et al. (January 2007), "A radar survey of main-belt asteroids: Arecibo observations of 55 objects during 1999–2003", Icarus, 186 (1): 126–151, Bibcode:2007Icar..186..126M, doi:10.1016/j.icarus.2006.08.018
  7. ^ Schmadel, Lutz D.; International Astronomical Union (2003), Dictionary of minor planet names, Berlin; New York: Springer-Verlag, p. 27, ISBN 978-3-540-00238-3.
  8. ^ Toth, Imre (December 1997), "First lightcurve observations and rotation of minor planet 127 Johanna", Planetary and Space Science, vol. 45, pp. 1625–1637, Bibcode:1997P&SS...45.1625T, doi:10.1016/S0032-0633(97)00141-4.
  9. ^ Szecsenyi-Nagy, G. (1983), "127 Johanna - Is it really the most quickly spinning asteroid known at this moment?", Asteroids, comets, meteors; Proceedings of the Meeting, Uppsala, Sweden, June 20–22, 1983, vol. 45, pp. 49–53, Bibcode:1983acm..proc...49S, doi:10.1016/S0032-0633(97)00141-4.

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