127 Johanna

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]

127 Johanna
A three-dimensional model of 127 Johanna based on its light curve.
Discovery
Discovered byPaul Henry and Prosper Henry
Discovery date5 November 1872
Designations
(127) Johanna
Pronunciation/dʒoʊˈhænə/[1]
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)
Aphelion2.9409 AU (439.95 Gm)
Perihelion2.57138 AU (384.673 Gm)
2.75615 AU (412.314 Gm)
Eccentricity0.067041
4.58 yr (1671.3 d)
17.92 km/s
67.782°
0° 12m 55.44s / day
Inclination8.2449°
31.154°
94.611°
Earth MOID1.60141 AU (239.568 Gm)
Jupiter MOID2.11199 AU (315.949 Gm)
TJupiter3.325
Physical characteristics
Dimensions122[2]
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]
0.0557 ± 0.0039[5]
Temperature~168 K
CX[6] (Tholen)
Ch[6] (Bus)
8.6,[2] 8.30[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.[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]

    References
    1. Noah Webster (1884) A Practical Dictionary of the English Language
    2. Yeomans, Donald K., "127 Johanna", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
    3. Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
    4. Behrend, Raoul, Courbes de rotation d'astéroïdes et de comètes (in French), Observatoire de Genève, retrieved 29 March 2013
    5. Tedesco, Edward F.; et al. (July 2002), "The Midcourse Space Experiment Infrared Minor Planet Survey", The Astronomical Journal, 124 (124), pp. 583–591, Bibcode:2002AJ....124..583T, doi:10.1086/340960.
    6. 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, 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, 45, pp. 49–53, Bibcode:1983acm..proc...49S, doi:10.1016/S0032-0633(97)00141-4.

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