C / 1984 A1 (Bradfield 1)
| C / 1984 A1 (Bradfield 1) [i] | |
|---|---|
| Properties of the orbit ( animation ) | |
| Orbit type | short-term |
| Numerical eccentricity | 0.952 |
| Perihelion | 1.36 AU |
| Aphelion | 55.6 AU |
| Major semi-axis | 28.5 AU |
| Sidereal period | ~ 152 a |
| Inclination of the orbit plane | 51.8 ° |
| Perihelion | December 27, 1983 |
| Orbital velocity in the perihelion | 35.7 km / s |
| history | |
| Explorer | WA Bradfield |
| Date of discovery | 7th January 1984 |
| Older name | 1983 XIX, 1984a |
| Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles . | |
C / 1984 A1 (Bradfield 1) is a short- period comet of the Halley type, which in 1984 could only be observed from the southern hemisphere .
Discovery and observation
The comet was in 1984 (local time) on the morning of January 8 William A. Bradfield in Australia with a mm 250 - f / 5.6 - Reflector discovered. It was his twelfth comet discovery, a little over three years after his last. During this period he searched for comets for a total of 384 hours. Bradfield estimated the comet's brightness to be about 11 mag.
At the time of its discovery, the comet was almost at its closest approach to Earth , but was already moving away from 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 in late May at the Mt John University Observatory in New Zealand at about 18 mag.
Orbit
For the comet, a relatively precise elliptical orbit could be determined from 33 observation data over a period of 142 days , which is inclined by around 52 ° to the ecliptic . At the point of the orbit closest to the Sun ( perihelion ), which the comet passed on December 27, 1983, it was located at a distance of 203.1 million km from the Sun in the area between the orbits of Earth and Mars . On November 8th it had already passed Mars at a distance of about 125.3 million km. On January 14, 1984, it came close to Earth to within 1.84 AU / 275.0 million km.
With a tissue edge parameter of 1.065 and an orbital period of less than 200 years, Comet Bradfield 1 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 1983/1984 still had an eccentricity of around 0.9520 and a semi-major axis of around 28.3 AU, so that its orbit period was around 151 years . The comet therefore approached the sun for the penultimate time in the first half of 1833 ( uncertainty ± 12 months), apparently remaining undetected. Due to the gravitational pull of the planets, in particular due to a relatively close passage of Jupiter on December 17, 1985 at a distance of about 3 ¾ AU, its orbital eccentricity was reduced to about 0.9506 and its semi-major axis to about 27.3 AU, so that its Orbital period shortened to about 143 years. When it reaches the point of its orbit furthest from the sun ( aphelion ) in 2055 , it will be about 8.0 billion km from the sun, over 53 times as far as the earth. Its orbital speed in the aphelion is only 0.90 km / s. The next perihelion of the comet is expected to take place in the second half of 2126 (uncertainty ± 11 months).
See also
Individual evidence
- ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Retrieved February 6, 2016 .
- ^ BG Marsden: Comets in 1984. In: Quarterly Journal of the Royal Astronomical Society. Vol. 27, 1986, pp. 590-606 ( bibcode : 1986QJRAS..27..590M ).
- ↑ NASA JPL Small-Body Database Browser: C / 1984 A1 (Bradfield 1). Retrieved February 6, 2016 .
- ^ 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 .