(3122) Florence
Asteroid (3122) Florence |
|
---|---|
Properties of the orbit ( animation ) | |
Orbit type | Cupid type |
Major semi-axis | 1.7691 AU |
eccentricity | 0.4233 |
Perihelion - aphelion | 1.0203 AU - 2.5180 AU |
Inclination of the orbit plane | 22.1508 ° |
Length of the ascending node | 336.0951 ° |
Argument of the periapsis | 27.8470 ° |
Sidereal period | 2,352 a |
Mean orbital velocity | 22.40 km / s |
Physical Properties | |
Medium diameter | 4.5 km |
Dimensions | ? | kg
Albedo | 0.20 |
Medium density | ? g / cm³ |
Rotation period | 2.3581 h |
Absolute brightness | 14.1 mag |
Spectral class | S. |
history | |
Explorer | SJ bus |
Date of discovery | March 2, 1981 |
Another name | 1981 ET 3 , 1983 CN 1 |
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items. |
(3122) Florence is a near-Earth asteroid from the Amor type that on 2 March 1981 by scolding John Bus at Siding Spring Observatory ( IAU code 413) in Australia was discovered.
The asteroid is named after the English social reformer Florence Nightingale (1820–1910).
Among the asteroids classified as potentially dangerous by NASA, Florence is the fourth largest with a diameter of 4.5 km, according to (53319) 1999 JM 8 (~ 7 km), (4183) Cuno (5.6 km) and (3200) Phaethon (5.1 km).
The earth comes close to the asteroid's orbit, which is stable for the foreseeable future, at the end of August / beginning of September, except for just under 0.047 AU (18 times the lunar distance). There were or will be fly-bys at almost this distance in 1930, 2017 and 2057, with the apparent brightness reaching 8.5 m . In the 87 and 40 earth years in between, the asteroid makes 37 and 17 orbits around the sun. The ratio of the orbital times is also very accurate at 73:31.
Until the flyby in 2017, the rotation period of 2.358 days was known, from fluctuations in brightness with an amplitude of 0.18 magnitude classes, and an estimate for the diameter of 4.35 km from the comparison of backscattered sunlight and thermal emission. The spectral class was uncertain, S or SQ.
During the flyby, Florence was observed intensively with the radars of the Arecibo Observatory and the Goldstone Deep Space Communications Complex . The duration and spectral bandwidth of the radar echo consistently indicate a diameter of 4.5 km, marginally larger than previously estimated. This means that material at the equator almost floats due to the rotation. The joint evaluation of transit times and Doppler shifts provides images (left as animation) that reveal an equatorial bulge and some crater-like depressions. It was also found that Florence has two moons, an outer one a good 300 m in diameter and an inner one about 200 m. Their orbits and periods of rotation (about 22 or almost 8 hours) provide the mass of the asteroid and thus the density. It is 1.4 g / cm 3 , which indicates considerable porosity. The spectrum of the asteroid in the visible and near IR range is very similar to that of the material found by the Chelyabinsk meteor , spectral class S, typical of common chondrites .
See also
Individual evidence
- ↑ Goldstone and Arecibo radar, August / September 2017.
- ↑ JPL Small-Body Database Browser: Close-Approach Data .
- ↑ WZWisniewski et al .: Photometric Observations of Asteroids 125 . Icarus 126, 1997, doi: 10.1006 / icar.1996.5665 .
- ↑ Asteroid Lightcurve Database (LCDB): (3122) Florence (based on WISE data from 2010/2011).
- ^ Lance Benner, Paul Chodas and Patrick Taylor: Telescopes Worldwide Collaborate to Observe Asteroid Florence During its Recent Close Approach to Earth . CNEOS ( JPL ), September 11, 2017.
Web links
- NASA website about Florence
- (3122) Florence in the database of the "Asteroids - Dynamic Site" (AstDyS-2, English).
- (3122) Florence in the Small-Body Database of the Jet Propulsion Laboratory .
- Discovery Circumstances of (3122) Florence according to the Minor Planet Center of the International Astronomical Union at the Harvard-Smithsonian Center for Astrophysics in Cambridge , Massachusetts (English)
- Fact sheet from the Eschenberg observatory in Winterthur (Switzerland) after the passage on September 1, 2017 - PDF, 435 kB