A three-dimensional model of 127 Johanna based on its light curve | |
Discovery | |
---|---|
Discovered by | Paul Henry and Prosper Henry |
Discovery date | 5 November 1872 |
Designations | |
(127) Johanna | |
Pronunciation | /dʒoʊˈhænə/[1] |
Named after | Joan of Arc |
A872 VB | |
Minor planet category | Main belt |
Orbital characteristics[2] | |
Epoch 31 July 2016 (JD 2457600.5) | |
Uncertainty parameter 0 | |
Observation arc | 98.53 yr (35989 d) |
|{{{apsis}}}|helion}} | 2.94 astronomical unit|AU (439.95 Gm) |
|{{{apsis}}}|helion}} | 2.57 AU (384.67 Gm) |
2.76 AU (412.31 Gm) | |
Eccentricity | 0.067041 |
Orbital period | 4.58 yr (1,671.3 d) |
Average Orbital speed | 17.92 km/s |
Mean anomaly | 67.782° |
Mean motion | 0° 12m 55.44s / day |
Inclination | 8.2449° |
Longitude of ascending node | 31.154° |
94.611° | |
Earth MOID | 1.60 AU (239.57 Gm) |
Jupiter MOID | 2.11 AU (315.95 Gm) |
TJupiter | 3.325 |
Physical characteristics | |
Dimensions | 122[2] 116.14±3.93 km[3] |
Mass | (3.08 ± 1.35) × 1018 kg[3] |
Mean density | 3.75±1.68 g/cm3[3] |
Rotation period | 12.7988 h (0.53328 d)[2][4] |
Geometric albedo | 0.0557±0.0039[5] |
Physics | ~168 K |
CX[6] (Tholen) Ch[6] (Bus) | |
Absolute magnitude (H) | 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 (60–73 mi) 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]
Original source: https://en.wikipedia.org/wiki/127 Johanna.
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