C/1987 P1 (Bradfield)
| Discovery | |
|---|---|
| Discovered by | William A. Bradfield |
| Discovery site | Dernancourt, Australia |
| Discovery date | 11 August 1987 |
| Designations | |
| 1987 XXIX, 1987s[1] | |
| Orbital characteristics[2] | |
| Epoch | 29 November 1989 (JD 2447128.5) |
| Observation arc | 245 days |
| Number of observations | 611 |
| Aphelion | ~330 AU |
| Perihelion | 0.869 AU |
| Semi-major axis | ~165 AU |
| Eccentricity | 0.99474 |
| Orbital period | ~2,120 years |
| Inclination | 34.088° |
| 268.09° | |
| Argument of periapsis | 73.899° |
| Mean anomaly | 0.010° |
| Last perihelion | 7 November 1987 |
| TJupiter | 0.988 |
| Earth MOID | 0.203 AU |
| Jupiter MOID | 1.223 AU |
| Physical characteristics[3] | |
Mean radius | ~1.3 km (0.81 mi) |
| Comet total magnitude (M1) | 6.0 |
C/1987 P1 (Bradfield) is a non-periodic comet that became visible to the naked eye in 1987. It is the 13th comet discovered by Australian astronomer, William A. Bradfield.
Physical characteristics
Spectrophotometric observations of the comet revealed high concentrations of (Mg,Fe)
2SiO
4 (olivine) in its coma, in addition to typical emissions of cyanogen (CN) and atomic carbon (C
2 and C
3) that is typically found in other comets.[4] Estimates of its mass loss rate is measured to be at approximately 1,000 kg/sec while it was 1.45 AU (217 million km) from the Sun.[3] Assuming that the entire sun-illuminated hemisphere of the comet's nucleus sheds material, this results in a lower limit for the nucleus radius of about 1.3 km (0.81 mi).[3]
References
- ^ "Comet Names and Designations". International Comet Quarterly. Retrieved 28 August 2025.
- ^ "C/1987 P1 (Bradfield) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 28 August 2025.
- ^ a b c M. S. Hanner; R. L. Newburn; R. D. Gehrungz; et al. (1990). "The Infrared Spectrum of Comet Bradfield (1987s) and the Silicate Emission feature". The Astrophysical Journal. 348: 312–321. Bibcode:1990ApJ...348..312H. doi:10.1086/168237.
- ^ B. S. Rautela; B. B. Sanwal (1988). "Spectrophotometric Study of Comet Bradfield (1987s)". Earth, Moon, and Planets. 43 (3): 221–225. Bibcode:1988EM&P...43..221R. doi:10.1007/BF00117094.
External links
- C/1987 P1 at the JPL Small-Body Database