C / 1989 A3 (Bradfield)
| C / 1989 A3 (Bradfield) [i] | |
|---|---|
| Properties of the orbit ( animation ) | |
| Orbit type | short-term |
| Numerical eccentricity | 0.978 |
| Perihelion | 0.420 AU |
| Aphelion | 37.3 AU |
| Major semi-axis | 18.9 AU |
| Sidereal period | ~ 81.9 a |
| Inclination of the orbit plane | 83.1 ° |
| Perihelion | 5th December 1988 |
| Orbital velocity in the perihelion | 64.6 km / s |
| history | |
| Explorer | WA Bradfield |
| Date of discovery | January 6, 1989 |
| Older name | 1988 XXIII, 1989c |
| Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles . | |
C / 1989 A3 (Bradfield) is a short-period comet from Halley -type in 1989 only on the southern hemisphere was observed. It is sometimes referred to as Bradfield 2 .
Discovery and observation
The comet was on the evening of January 6, 1989 (local time) by William A. Bradfield in Australia with a 250 mm - f / 5.6 - Reflector discovered. It was his fourteenth comet discovery, about a year and a half after his last. During this period he had searched for comets for a total of 164 hours. Bradfield estimated the comet's brightness to be about 12 mag.
At the time of its discovery, the comet was already moving away from the earth and the sun . It was therefore no brighter than when it was discovered. The comet could only be seen from the southern hemisphere and the last observation was made on March 10th at the Siding Spring Observatory in Australia at about 16 mag.
Orbit
For the comet, from 16 observation data over a period of 53 days, only a limited precise elliptical orbit could be determined, which is inclined by around 83 ° to the ecliptic . Its orbit is thus almost perpendicular to the orbits of the planets. At the point of the orbit closest to the sun ( perihelion ), which the comet passed on December 5, 1988, its distance from the sun at 62.9 million km was roughly the same as that of Mercury , which it was on November 28 to around 46.7 million .km had approached. On December 2nd it had passed Venus in about 61.5 million km and on December 21, 1988 it came close to Earth to about 1.24 AU / 185.2 million km.
With a tissue margin parameter of 0.372 and an orbital period of less than 200 years, Comet Bradfield is a typical member of the Halley family of short-period comets.
The comet moves in an elongated elliptical orbit around the sun. Based on the currently known orbital elements , its orbit some time before its passage through the inner solar system in 1988/89 still had an eccentricity of about 0.9773 and a semi-major axis of about 18.7 AU, so that its orbit period was about 80.7 Years ago. The comet therefore approached the sun for the penultimate time around 1908, but apparently remained undetected. Due to the gravitational pull of the planets, especially due to two relatively close passages of Jupiter on February 3, 1988 in about 4 AU and on April 28, 1989 in about 4 ¼ AU, its orbital eccentricity was about 0.9776 and its semi-major axis about 18.8 AU increased so that its orbital period increased to about 81.3 years. When it reaches the point of its orbit furthest from the sun ( aphelion ) in 2029 , it will be about 5.6 billion km from the sun, over 37 times as far as the earth and slightly further than Neptune . Its orbit speed in the aphelion is only 0.73 km / s. The comet's next perihelion is expected to occur around 2070.
See also
Web links
Individual evidence
- ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Retrieved March 1, 2016 .
- ^ JV Scotti: Periodic Comet Extreme Observations. Lunar and Planetary Laboratory, University of Arizona, 2013, p. 8 ( PDF; 353 kB ).
- ↑ NASA JPL Small-Body Database Browser: C / 1989 A3 (Bradfield). Retrieved March 1, 2016 .
- ^ YR Fernández: List of Jupiter-Family and Halley-Family Comets. Retrieved March 1, 2016 .
- ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .