8 Flora

8 Flora (pronounced /ˈflɔərə/, Latin: Flōra) 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.[8] It is the seventh brightest asteroid with a mean opposition magnitude of +8.7.[9] 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.[10]
Size comparison: the first 10 asteroids profiled against Earth's Moon. Flora is third from the right.

Discovery and naming

Flora was discovered by J. R. Hind on October 18, 1847. It was his second asteroid discovery after 7 Iris.

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), mother of Spring, and whose Greek equivalent is Chloris (who has her own asteroid, 410 Chloris).

Characteristics
The orbit of 8 Flora compared with the orbits of Earth, Mars and Jupiter

Lightcurve analysis indicates that Flora's pole points towards ecliptic coordinates (β, λ) = (16°, 160°) with a 10° uncertainty.[3] This gives an axial tilt of 78°, plus or minus ten degrees.

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.[citation needed]

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.[11] This meteorite type comprises about 38% of all meteorites impacting the Earth.

Notable facts

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.[12] Flora had come to opposition on 1917 February 13, 40 days earlier.[12] This mistake was uncovered only in 1995.[13][12]

In the film The Green Slime, the asteroid Flora falls out of orbit and is on a collision course with Earth.

References

1. ^ a b c d e "JPL Small-Body Database Browser: 8 Flora". 2008-04-14 last obs. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=8. Retrieved 2008-11-27.
2. ^ a b c Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. http://home.earthlink.net/~jimbaer1/astmass.txt. Retrieved 2008-11-27.
3. ^ a b Torppa, J.; et al. (2003). "Shapes and rotational properties of thirty asteroids from photometric data" (PDF). Icarus 164: 346. doi:10.1016/S0019-1035(03)00146-5. http://www.rni.helsinki.fi/~mjk/thirty.pdf.
4. ^ Michalak, G. (2001). "Determination of asteroid masses". Astronomy & Astrophysics 374: 703–711. doi:10.1051/0004-6361:20010731. Retrieved 2008-11-10.
5. ^ Michalak2001 assumed masses of perturbing asteroids used in calculations of perturbations of the test asteroids.
6. ^ 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.
7. ^ Donald H. Menzel and Jay M. Pasachoff (1983). A Field Guide to the Stars and Planets (2nd ed.). Boston, MA: Houghton Mifflin. pp. 391. ISBN 0395348358.
8. ^ Binsel, Richard P.; Gehrels, Tom and Matthews, Mildred Shapley (editors); Asteroids II; published 1989 by University of Arizona Press; pp. 1038-1040. ISBN 0-8165-1123-3
9. ^ The Brightest Asteroids
10. ^ 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: 83–114. doi:10.1016/0019-1035(84)90140-4.
11. ^ Nesvorný, D.; et al. (2002). "The Flora Family: A Case of the Dynamically Dispersed Collisional Swarm?". Icarus 157: 155. doi:10.1006/icar.2002.6830.
12. ^ a b c 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. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1996A%26A...312..496S&db_key=AST&data_type=HTML&format=&high=43a5c7f7b428230.
13. ^ "IAUC 6174". http://cfa-www.harvard.edu/iauc/06100/06174.html#Item1.

External links

* shape model deduced from lightcurve
* "Announcement of discovery of Flora", MNRAS 8 (1848) 82
* Orbital simulation from JPL (Java)
* 8 Flora at opposition Nov 15th, 2007 (0.89AU from Earth)
* Yeomans, Donald K.. "Horizons system". NASA JPL. http://ssd.jpl.nasa.gov/?horizons. Retrieved 2007-03-20. — Horizons can be used to obtain a current ephemeris.