127 Johanna

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127 Johanna
127Johanna (Lightcurve Inversion).png
A three-dimensional model of 127 Johanna based on its light curve.
Discovery
Discovered by Paul Henry and Prosper Henry
Discovery date November 5, 1872
Designations
Named after
Joan of Arc
Minor planet category Main belt
Orbital characteristics[1]
Epoch December 31, 2006 (JD 2454100.5)
Aphelion 438.576 Gm (2.932 AU)
Perihelion 385.859 Gm (2.579 AU)
412.218 Gm (2.756 AU)
Eccentricity 0.064
1670.707 d (4.57 a)
17.92 km/s
36.831°
Inclination 8.245°
31.448°
91.496°
Physical characteristics
Dimensions 116.14 ± 3.93[2] km
Mass (3.08 ± 1.35) × 1018[2] kg
Mean density
3.75 ± 1.68[2] g/cm3
12.7988[3] h
Albedo 0.0557 ± 0.0039[4]
Temperature ~168 K
Spectral type
CX[5] (Tholen)
Ch[5] (Bus)
8.30[4]

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

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.[7]

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.[8] The present day established rotation period of this object is 12.7988 hours.[3]

During 2001, 127 Johanna was observed by radar from the Arecibo Observatory. The return signal matched an effective diameter of 117 ± 21 km.[5] 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.[4] A 2012 study gave a refined diameter estimate of 116.14 ± 3.93 km.[2]

References[edit]

  1. ^ Yeomans, Donald K., "127 Johanna", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-03-25. 
  2. ^ a b c d Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: 98-118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009.  See Table 1.
  3. ^ a b Behrend, Raoul, Courbes de rotation d'astéroïdes et de comètes (in French), Observatoire de Genève, retrieved 2013-03-29 
  4. ^ a b c Tedesco, Edward F. et al. (July 2002), "The Midcourse Space Experiment Infrared Minor Planet Survey", The Astronomical Journal 124 (124): 583-591, Bibcode:2002AJ....124..583T, doi:10.1086/340960. 
  5. ^ 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 
  6. ^ 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. 
  7. ^ Toth, Imre (December 1997), "First lightcurve observations and rotation of minor planet 127 Johanna", Planetary and Space Science 45: 1625-1637, Bibcode:1997P&SS...45.1625T, doi:10.1016/S0032-0633(97)00141-4. 
  8. ^ 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 45: 49-53, Bibcode:1983acm..proc...49S, doi:10.1016/S0032-0633(97)00141-4.