| Discovery | |
|---|---|
| Discovered by | Graeme White Emilio Ortiz Carlos Bolelli |
| Discovery date | 18 May 1970 |
| Designations | |
| Alternative designations | 1970f 1970 VI |
| Orbital characteristics | |
| Epoch | 29 May 1970 (JD 2440735.5) |
| Observation arc | 14 days |
| Earliest precovery date | 16 May 1970 |
| Number of observations | 9 |
| Orbit type | Kreutz sungrazer |
| Aphelion | 347.565 AU |
| Perihelion | 0.00884 AU |
| Semi-major axis | 173.787 AU |
| Eccentricity | 0.99995 |
| Orbital period | 2,291.04 years |
| Inclination | 138.95° |
| Longitude of ascending node | 336.82° |
| Argument of periapsis | 61.103° |
| Last perihelion | 14 May 1970 |
| TJupiter | –0.058 |
| Earth MOID | 0.4901 AU |
| Jupiter MOID | 2.8494 AU |
| Physical characteristics | |
| Apparent magnitude | 1.0 (1970 apparition) |
Comet White–Ortiz–Bolelli (formal designations: C/1970 K1, 1970 VI, and 1970f) was a bright comet which appeared in 1970. It was a member of the Kreutz sungrazers, a family of comets which resulted from the break-up of a large parent comet several centuries ago. It was already easily visible to the naked eye when first discovered, and reached a maximum apparent magnitude of +1 (about as bright as planet Saturn).
Discovery
Comet White–Ortiz–Bolelli was first spotted on May 16 by Albert and Ronald Snelgar on May 16 in Halls Creek, Western Australia, and then into the Northern Territory on successive nights. They advised the discovery to Halls Creek police who disregarded the discovery. It was then officially discovered on May 18 by Graeme White, an Australian amateur astronomer in Wollongong, New South Wales. He sighted the comet in binoculars shortly after sunset, and described it as having a star-like head at apparent magnitude 1-2, and a short tail about 1 degree long. He spotted it again on May 20 by naked eye as well as binoculars, and by this time the tail had grown to 10° in length.
The second independent discovery was made on May 21 by Air France pilot Emilio Ortiz, from a location about 400 km east of Madagascar. Ortiz saw the comet from his cockpit, and reported a magnitude of 0.5 to 1.0 and a tail about 5–8° long. A few hours later, Carlos Bolelli, a technician at the Cerro Tololo Inter-American Observatory in Chile became the third independent discoverer of the comet, although he saw only the tail, as the head was beneath the horizon.
Subsequent observations
Numerous independent discoveries were made in the days immediately following the comet's discovery, but astronomical naming conventions only allowed the comet to be given the names of the first three. All sightings of the comet were made from the southern hemisphere, due to the orientation of its orbit with respect to the Earth.
Throughout the comet's brief appearance, it could only be seen low in the sky for a short time after sunset, but it was most easily visible on May 24. After that it faded rapidly, and by 1 June it had already faded to below naked-eye visibility. The last definite detection of the comet was made on June 7, when it appeared as a faint, ill-defined nebulosity. Increasing moonlight and the comet's decreasing brightness prevented any further visual sightings of the comet.
Orbit
The comet's sudden appearance very close to the Sun and rapid subsequent decline in brightness both pointed to it being a sungrazing comet, and calculations of its orbit by Brian G. Marsden backed this suggestion. Marsden showed that the comet had reached perihelion (closest approach to the Sun) on May 14, at a distance of just 0.0088 AU (1.32 million km), or 2 solar radii.
The calculated orbit pinned down White-Ortiz-Bolelli as a member of the Kreutz sungrazers, a group of comets which all originate from the fragmentation of one giant parent comet several hundred years ago, and which has provided some of the brightest comets ever seen. Kreutz Sungrazers all travel on similar orbits, which result in them being most easily visible from the southern hemisphere, between August and April. Kreutz sungrazers appearing between May and July may come and go unseen, as they approach from directly behind the Sun as seen from Earth; the only previous Kreutz Sungrazer seen during these months was the Eclipse Comet of 1882, which was only observed once, during a total solar eclipse.
Before White–Ortiz–Bolelli, studies had divided the Kreutz Sungrazers into two sub-groups, originating from fragmentations at different orbits, but White-Ortiz-Bolelli seemed to be a member of neither. Studies showed that it probably broke away from the comet that spawned Subgroup II, before the main fragmentation, and it was classed as the first (and so far only) member of Subgroup IIa.
Having an observation arc of only 14 days, the long-term trajectory of the comet is poorly constrained. The orbital period is basically unknown but assumed to be a few thousand years with an orbital inclination of 139 degrees.
References
- E. Roemer (1970). "Comet Notes". Publications of the Astronomical Society of the Pacific. 82 (488): 928. Bibcode:1970PASP...82..928R. doi:10.1086/128991.
- G. W. Kronk. "C/1970 K1 (White-Ortiz-Bolelli)". Cometography.com. Archived from the original on 2 March 2005.
- "Comet Names and Designations". International Comet Quarterly. Retrieved 12 November 2024.
- ^ "C/1970 K1 (White-Ortiz-Bolelli) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 31 August 2023.
- ^ B. G. Marsden (1971). "Comets of 1970". Quarterly Journal of the Royal Astronomical Society. 12: 244–273. Bibcode:1971QJRAS..12..244M.
- ^ Z. Sekanina; P. W. Chodas (2002). "Fragmentation Origin of Major Sungrazing Comets C/1970 K1, C/1880 C1, and C/1843 D1". The Astrophysical Journal. 581 (2): 1389–1398. Bibcode:2002ApJ...581.1389S. doi:10.1086/344261.
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