8 Flora

From Wikipedia, the free encyclopedia

8 Flora  

Convex hull model of 8 Flora
Discovery
Discovered by:	J.R. Hind
Discovery date:	October 18, 1847
Alternative names:	none
Minor planet category:	Main belt (Flora family)
Orbital characteristics
Epoch November 26, 2005 (JD 2453700.5)
Aphelion distance:	380.850 Gm (2.546 AU)
Perihelion distance:	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)
Avg. 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[1]
Temperature:	~180 K max: 276 K (+3 °C)
Spectral type:	S-type asteroid
Absolute magnitude:	6.49

8 Flora (IPA: [ˈfloɹə]) is a large, bright main belt asteroid.

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

[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.^[5] This meteorite type comprises about 38% of all meteorites impacting the Earth.

[edit] Trivia

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.^[6][7]

[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. ^ Nesvorný, D.; et al (2002). "The Flora Family: A Case of the Dynamically Dispersed Collisional Swarm?". Icarus 157: 155. 
6. ^ IAUC 6174.
7. ^ 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

• 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. Retrieved on 2007-03-20. — Horizons can be used to obtain a current ephemeris.