|Discovered by||J.R. Hind|
|Discovery date||October 18, 1847|
|Minor planet category||Main belt (Flora family)|
|Epoch November 26, 2005 (JD 2453700.5)|
|Aphelion||380.850 Gm (2.546 AU)|
|Perihelion||277.995 Gm (1.858 AU)|
|Semi-major axis||329.422 Gm (2.202 AU)|
|Orbital period||1193.549 d (3.27 a)|
|Average orbital speed||19.95 km/s|
|Longitude of ascending node||111.011°|
|Argument of perihelion||285.128°|
|Proper orbital elements|
|Proper semi-major axis||2.2014283 AU|
|Proper mean motion||110.205216 deg / yr|
|Proper orbital period||3.26663 yr
|Precession of perihelion||32.016655 arcsec / yr|
|Precession of the ascending node||−35.510731 arcsec / yr|
128 km (mean)
|Mean density||3.13±1.43 g/cm³
|Equatorial surface gravity||~0.045 m/s²|
|Escape velocity||~0.081 km/s|
|Rotation period||0.533 d (12.799 h)|
max: 276 K (+3 °C)
|Spectral type||S-type asteroid|
|Apparent magnitude||7.9 to 11.6|
|Absolute magnitude (H)||6.49|
|Angular diameter||0.21" to 0.053"|
8 Flora is a large, bright main-belt asteroid. It is the innermost large asteroid: no asteroid closer to the Sun has a diameter above 25 kilometres or two-elevenths that of Flora itself, and not until the tiny 149 Medusa was discovered was a single asteroid orbiting at a closer mean distance known. It is the seventh brightest asteroid with a mean opposition magnitude of +8.7. Flora can reach a magnitude of +7.9 at a favorable opposition near perihelion, such as occurred in November 2007. Flora may be the residual core of an intensely heated, thermally evolved, and magmatically differentiated planetesimal which was subsequently disrupted.
Discovery and naming
The name Flora was proposed by John Herschel, from Flora, the Latin goddess of flowers and gardens, wife of Zephyrus (the personification of the West wind), and mother of Spring. The Greek equivalent is Chloris, who has her own asteroid, 410 Chloris, but in Greek Flora is also called Chloris (8 Χλωρίς).
Flora is the parent body of the Flora family of asteroids, and by far the largest member, comprising about 80% of the total mass of this family. Nevertheless, Flora was almost certainly disrupted by the impact(s) that formed the family, and is probably a gravitational aggregate of most of the pieces.
Flora's spectrum indicates that its surface composition is a mixture of silicate rock (including pyroxene and olivine) and nickel-iron metal. Flora, and the whole Flora family generally, are good candidates for being the parent bodies of the L chondrite meteorites. This meteorite type comprises about 38% of all meteorites impacting the Earth.
During an observation on March 25, 1917, 8 Flora was mistaken for the 15th magnitude star TU Leonis, which led to that star's classification as a U Geminorum cataclysmic variable star. Flora had come to opposition on 1917 February 13, 40 days earlier. This mistake was uncovered only in 1995.
In the film The Green Slime, the asteroid Flora falls out of orbit and is on a collision course with Earth.
On July 26, 2013, Flora at magnitude 8.8 occulted the star 2UCAC 22807162 over parts of South America, Africa, and Asia.
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- Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. Retrieved 2008-11-27.
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- Michalak2001 assumed masses of perturbing asteroids used in calculations of perturbations of the test asteroids.
- Density (D=Mass/Volume=4.376/1.317=~3.3) calculated using JPL radius of 68km and the Michalak2001 assumed mass of 4.376E+18.
- Donald H. Menzel and Jay M. Pasachoff (1983). A Field Guide to the Stars and Planets (2nd ed.). Boston, MA: Houghton Mifflin. p. 391. ISBN 0-395-34835-8.
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- The Brightest Asteroids
- Gaffey, Michael (1984). "Rotational spectral variations of asteroid (8) Flora: Implications for the nature of the S-type asteroids and for the parent bodies of the ordinary chondrites". Icarus 60 (1): 83–114. Bibcode:1984Icar...60...83G. doi:10.1016/0019-1035(84)90140-4.
- Nesvorný, D.; et al. (2002). "The Flora Family: A Case of the Dynamically Dispersed Collisional Swarm?". Icarus 157 (1): 155. Bibcode:2002Icar..157..155N. doi:10.1006/icar.2002.6830.
- Schmadel, L. D.; Schmeer, P.; Börngen, F. (August 1996). "TU Leonis = (8) Flora: the non-existence of a U Geminorum star". Astron. Astrophys. 312: 496. Bibcode:1996A&A...312..496S.
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- Asteroid Occultation Index Page
- shape model deduced from lightcurve
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- JPL Ephemeris