127 Johanna

Short description: Main-belt asteroid

127 Johanna

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

MPC designation

| (127) Johanna
Pronunciation| /dʒoʊˈhænə/[1]
Named after| Joan of Arc

Alternative designations

| 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)

Semi-major axis

| 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°

|{{{apsis}}}|helion}}

| 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

Spectral type

| 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]

## References

1. ↑ Noah Webster (1884) A Practical Dictionary of the English Language
2. ↑ 2.0 2.1 2.2 2.3 Yeomans, Donald K., "127 Johanna", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=127, retrieved 12 May 2016.
3. ↑ 3.0 3.1 3.2 3.3 Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: pp. 98–118, doi:10.1016/j.pss.2012.03.009, Bibcode: 2012P&SS...73...98C. See Table 1.
4. ↑ 4.0 4.1 Behrend, Raoul (in French), Courbes de rotation d'astéroïdes et de comètes, Observatoire de Genève, http://obswww.unige.ch/~behrend/page_cou.html, retrieved 2013-03-29
5. ↑ 5.0 5.1 5.2 Tedesco, Edward F. et al. (July 2002), "The Midcourse Space Experiment Infrared Minor Planet Survey", The Astronomical Journal 124 (124): pp. 583–591, doi:10.1086/340960, Bibcode: 2002AJ....124..583T.
6. ↑ 6.0 6.1 6.2 6.3 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, doi:10.1016/j.icarus.2006.08.018, Bibcode: 2007Icar..186..126M
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, https://books.google.com/books?id=KWrB1jPCa8AC&pg=PA27.
8. ↑ Toth, Imre (December 1997), "First lightcurve observations and rotation of minor planet 127 Johanna", Planetary and Space Science 45: pp. 1625–1637, doi:10.1016/S0032-0633(97)00141-4, Bibcode: 1997P&SS...45.1625T.
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, doi:10.1016/S0032-0633(97)00141-4, Bibcode: 1983acm..proc...49S.

## External links

* 127 Johanna at AstDyS-2, Asteroids—Dynamic Site
* Ephemeris * Observation prediction * Orbital info * Proper elements * Observational info
* 127 Johanna at the JPL Small-Body Database
* Close approach * Discovery * Ephemeris * Orbit diagram * Orbital elements * Physical parameters

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