C / 1975 E1 (Bradfield)
| C / 1975 E1 (Bradfield) [i] | |
|---|---|
| Properties of the orbit ( animation ) | |
| Orbit type | hyperbolic |
| Numerical eccentricity | 1.0014 |
| Perihelion | 1.217 AU |
| Inclination of the orbit plane | 55.2 ° |
| Perihelion | April 4th 1975 |
| Orbital velocity in the perihelion | 38.2 km / s |
| history | |
| Explorer | WA Bradfield |
| Date of discovery | March 12, 1975 |
| Older name | 1975 V, 1975d |
| Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles . | |
C / 1975 E1 (Bradfield) is a comet that was observed in 1975 and 1976.
Discovery and observation
The comet was on the evening of March 12, 1975 (local time) by William A. Bradfield in Australia with a 150 mm - f / 5.5 - Refractor discovered. It was his third comet discovery, exactly three years after his first and 13 months after his second. He had searched for comets for a total of 145 hours since his last discovery. He estimated the comet's brightness to be around 9 mag.
By the end of April the brightness had already dropped to 10 mag. At first the comet could only be observed from the southern hemisphere , an observation from the northern hemisphere was only possible from the beginning of 1976, when the comet was already faint again with only 17-18 mag. The last observation was on April 5, 1976 by Elizabeth Roemer in Arizona .
Scientific evaluation
Spectroscopic studies by Pol Swings at the European Southern Observatory on March 16 and 17, 1975 showed comet-typical emission lines of C 2 , C 3 and CN, but none of CH.
Orbit
For the comet, a very precise hyperbolic orbit could be determined from 52 observation data over a period of about one year , which is inclined by about 55 ° to the ecliptic . At the point of the orbit closest to the Sun ( perihelion ), which the comet passed on April 4, 1975, it was at 182.1 million km of the sun between the orbits of Mars and Earth . On February 4th it had already passed Venus at a distance of about 135.0 million km and on April 19 it came close to Earth to within 1.84 AU / 275.0 million km.
Based on the currently known orbital elements , its orbit still had a closed elliptical shape some time before the passage of the inner solar system in 1975 with an eccentricity of about 0.99997 and a semi-major axis of about 43,500 AU, so that its orbital period was about 9 million Years ago. It may have been a “dynamic new” comet from the Oort cloud, or had only come close to the sun a few times before. However, due to the gravitational pull of the planets, especially due to the relatively close passages of Jupiter on July 26, 1974 at a distance of only about 2 ⅓ AU and at Saturn on February 7, 1976 at a distance of just over 7 AU, its orbital eccentricity was increased to about 1.00103 so that the comet is now departing in a hyperbolic orbit. The comet will therefore not return to the inner solar system.
See also
Individual evidence
- ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Retrieved December 16, 2015 .
- ^ BG Marsden, E. Roemer: Comets in 1975. In: Quarterly Journal of the Royal Astronomical Society. Vol. 19, 1978, pp. 59-89 ( bibcode : 1978QJRAS..19 ... 59M ).
- ^ GW Kronk, M. Meyer: Cometography - A Catalog of Comets, Volume 5, 1960-1982. Cambridge University Press, Cambridge 2010, ISBN 978-0-521-87226-3 , pp. 446-449.
- ^ IAU Central Bureau for Astronomical Telegrams - IAUC 2761: Obs of comets; 1975d; Transient X-Ray source; Novae. Retrieved December 16, 2015 .
- ↑ NASA JPL Small-Body Database Browser: C / 1975 E1 (Bradfield). Retrieved December 14, 2015 .
- ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .
- ^ BG Marsden, Z. Sekanina, E. Everhart: New Osculating Orbits for 110 Comets and Analysis of Original Orbits for 200 Comets. In: The Astronomical Journal. Vol. 83, no. 1, 1978, pp. 64-71 doi: 10.1086 / 112177 ( bibcode : 1978AJ ..... 83 ... 64M ).