127 Johanna
|
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 |
| 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) | |
Average orbital speed | 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] | |
|
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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 carbonaceous 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
- ↑ Yeomans, Donald K., "127 Johanna", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-03-25.
- ↑ 2.0 2.1 2.2 2.3 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.
- ↑ 3.0 3.1 Behrend, Raoul, Courbes de rotation d'astéroïdes et de comètes (in French), Observatoire de Genève, retrieved 2013-03-29
- ↑ 4.0 4.1 4.2 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.
- ↑ 5.0 5.1 5.2 5.3 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
- ↑ 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.
- ↑ 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.
- ↑ 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.
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