Girish Mahajan (Editor)

127 Johanna

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Discovery date  5 November 1872
Observation arc  98.53 yr (35989 d)
Discovered  5 November 1872
Spectral type  C-type asteroid
Discovery site  Paris Observatory
Minor planet category  Main belt
Aphelion  2.9409 AU (439.95 Gm)
Orbits  Sun
Named after  Joan of Arc
127 Johanna httpsuploadwikimediaorgwikipediacommonsthu
Discovered by  Paul Henry and Prosper Henry
Perihelion  2.57138 AU (384.673 Gm)
Discoverers  Paul Henry and Prosper Henry, Prosper Henry
Similar  128 Nemesis, 165 Loreley, 162 Laurentia, 76 Freia, 167 Urda

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. 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.

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.

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. The present day established rotation period of this object is 12.7988 hours.

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

References

127 Johanna Wikipedia


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