8 Flora

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8 Flora  
Discovery
Discovered by J.R. Hind
Discovery date October 18, 1847
Designations
Alternative names none
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)
Eccentricity 0.1561
Orbital period 1193.549 d (3.27 a)
Average orbital speed 19.95 km/s
Mean anomaly 156.401°
Inclination 5.886°
Longitude of ascending node 111.011°
Argument of perihelion 285.128°
Physical characteristics
Dimensions 145×145×120 km [1][2]
Mass ~3.6×1018 kg
Mean density ~2.7 g/cm³[3]
Equatorial surface gravity ~0.045 m/s²
Escape velocity ~0.081 km/s
Rotation period 0.5363 d (12.87 h)[4]
Albedo 0.243 (geometric)[1]
Temperature ~180 K
max: 276 K (+3 °C)
Spectral type S-type asteroid
Apparent magnitude 7.9[5] to 11.6
Absolute magnitude 6.49
Angular diameter 0.21" to 0.053"

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[6]. It is the seventh brightest asteroid with a mean opposition magnitude of +8.7[7]. Flora can reach a magnitude of +7.9 at a favorable opposition near perihelion, such as occurred in November 2007.

Size comparison: the first 10 asteroids profiled against Earth's Moon. Flora is third from the right.
Size comparison: the first 10 asteroids profiled against Earth's Moon. Flora is third from the right.

Contents

[edit] 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 personnification of the West wind), mother of Spring, and whose Greek equivalent is Chloris (who has her own asteroid, 410 Chloris).

[edit] Characteristics

Lightcurve analysis indicates that Flora's pole points towards ecliptic coordinates (β, λ) = (16°, 160°) with a 10° uncertainty.[2] 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.

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

[edit] Notable facts

During an observation on March 25, 1917, 8 Flora was mistaken for the star TU Leonis, which led to that star's classification as a U Geminorum cataclysmic variable star. This mistake was uncovered only in 1995.[9][10]

[edit] References

  1. ^ a b Supplemental IRAS Minor Planet Survey.
  2. ^ a b Torppa, J.; et al (2003). "Shapes and rotational properties of thirty asteroids from photometric data". Icarus 164: 346. 
  3. ^ Krasinsky, G. A.; et al (2002). "Hidden Mass in the Asteroid Belt". Icarus 158: 98. 
  4. ^ Planetary Data System Small Bodies Node, lightcurve parameters.
  5. ^ Donald H. Menzel and Jay M. Pasachoff (1983). A Field Guide to the Stars and Planets, 2nd edition, Boston, MA: Houghton Mifflin, p. 391. ISBN 0395348358. 
  6. ^ 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
  7. ^ The Brightest Asteroids
  8. ^ Nesvorný, D.; et al (2002). "The Flora Family: A Case of the Dynamically Dispersed Collisional Swarm?". Icarus 157: 155. 
  9. ^ IAUC 6174.
  10. ^ Schmadel, L. D.; Schmeer, P.; Börngen, F. (08 1996). "TU Leonis = (8) Flora: the non-existence of a U Geminorum star". Astron. Astrophys. 312: 496. 

[edit] External links

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