C / 1961 O1 (Wilson-Hubbard)

from Wikipedia, the free encyclopedia
C / 1961 O1 (Wilson-Hubbard) [i]
Properties of the orbit ( animation )
Epoch:  August 9, 1961 ( JD 2,437,520.5)
Orbit type long-period
Numerical eccentricity 0.999962
Perihelion 0.040 AU
Aphelion 2116 AE
Major semi-axis 1058 AE
Sidereal period ~ 34,400 a
Inclination of the orbit plane 24.2 °
Perihelion 17th July 1961
Orbital velocity in the perihelion 210 km / s
history
Explorer A. S. Wilson, W. B. Hubbard, et al. a.
Date of discovery July 23, 1961
Older name 1961 V, 1961d
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1961 O1 (Wilson-Hubbard) is a comet that could be seen with the naked eye in 1961 . Some consider it one of the " great comets ".

Discovery and observation

The comet was still unobserved 5:53 to 8:56 on July 18 1961 UT of the earth seen from in front of the sun passed by. About five days later the pilot A. Stewart Wilson spotted him on the morning of July 23rd (local time) aboard a Boeing 707 airliner on the flight from Honolulu to Portland (Oregon) from an altitude of 8800 m. He recognized a faint vertical streak of light on the horizon and compared his appearance to a distant searchlight, while his colleagues in the cockpit mistook it for an aurora . Wilson continued to watch it with binoculars and eventually recognized it as a comet. He estimated its brightness to be 3.5 mag. Around the same time, William B. Hubbard, a student at the McDonald Observatory in Texas, discovered the comet's tail while observing an artificial satellite in the eastern sky. He estimated the brightness to be 3 mag.

The first person who presumably had seen the comet, however, was Anna Ras, a stewardess who had already seen the comet's tail at a length of 15 ° during a flight over Libya before sunrise on July 23 (local time) and thus about 8 hours before Wilson and Hubbard had noticed.

A day later there were still numerous independent discoveries, one in Spain from the ground and three more by pilots of commercial aircraft over the United States . At the same time, the discovery was also confirmed by astronomers, including Kōichirō Tomita and George Van Biesbroeck . The news about the comet spread quickly because of the numerous discoveries. The comet was closely observed during the remainder of July. Around July 25, several observers described the comet's tail, which is up to 25 ° long, as well as a 2–3 ° long counter-tail. The brightness of the comet quickly decreased and at the end of the month was only 4–5 mag. It could be seen with the naked eye for the last time in the first days of August and by mid-August the tail had almost disappeared and the brightness of the comet had dropped to just 11-12 mag.

The comet could only be photographed a few times in September and October. The last observation was made on November 9, 1961 by Tomita in Tokyo .

The comet reached a maximum brightness of 3 mag.

Scientific evaluation

In the last week of July, spectrographic observations of the comet were made at the Observatoire de Haute-Provence and the Portage Lake Observatory in Michigan . The spectrograms showed comet-typical emission lines of CN, C 2 and NH 2 (but no CH or C 3 ), as well as strong sodium D lines .

After a preliminary determination of the orbit by Michael Philip Candy in 1961, Branham derived elements of an elliptical orbit for the comet from 38 observations over a period of 107 days in a 1968 study . Marsden , Sekanina and Everhart used these orbital elements to calculate the original and future values ​​of the semiaxial major axis of the orbit.

Seventeen years after his orbit calculations, Branham was dissatisfied with his earlier calculations, as they were based on mathematical methods that were now outdated and only partially took into account the various causes of orbital disturbances . Therefore, he repeated his investigation once again, including 84 observations over a period of 107 days, as well as taking into account the gravitational influence of all planets and the relativistic effects of the comet's close flyby to the sun. These newly determined path elements are given in the info box. They differ numerically only slightly from those previously determined, but the differences have clear effects on the extrapolation of the comet's orbit far into the past or into the future. Therefore, Everhart and Marsden also performed new calculations of the original and future value of the semiaxial axis of the orbit with the new orbital elements.

Orbit

For the comet, an elliptical orbit could be determined from 84 observation data over a period of 107 days, which is inclined by around 24 ° to the ecliptic . At the point of the orbit closest to the sun ( perihelion ), which the comet traversed on July 17, 1961, it was only about 7.6 solar radii above its surface at about 6.0 million km from the sun . On July 22nd it passed Mercury at a distance of 27.6 million km and on July 30th it passed Venus at a distance of 56.5 million km . On August 14, it reached the closest approach to earth with 0.79 AU / 118.3 million km.

The comet moves in an extremely elongated elliptical orbit around the sun. According to the orbital elements, which are afflicted with a certain uncertainty, its orbit before its passage through the inner solar system in 1961 still had an eccentricity of around 0.99996 and a semi-major axis of around 1270 AU, so that its orbit period was around 45,000 years. Due to the gravitational pull of the planets, in particular due to a relatively close passage to Jupiter on August 22, 1962 at a distance of about 4½ AU, the orbital eccentricity was reduced to about 0.99991 and the semi-major axis to about 444 AU, so that its orbital time is reduced to now about 9,345 years shortened.

See also

Web links

Individual evidence

  1. ^ John E. Bortle: International Comet Quarterly - The Bright-Comet Chronicles. Retrieved September 25, 2015 .
  2. ^ 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. 38-42.
  3. ^ P. Moore, R. Rees: Patrick Moore's Data Book of Astronomy . Cambridge University Press, Cambridge 2011, ISBN 978-0-521-89935-2 , p. 271.
  4. ↑ J. Dufay, A. Barann: Le specter de la comète Wilson-Hubbard (1961 d). In: Annales d'Astrophysique. 25 e Année, No. 5, 1962, pp. 301-309, bibcode : 1962AnAp ... 25..301D .
  5. ^ FD Miller: On the Spectrum of Comet Wilson (1961d). In: Publications of the Astronomical Society of the Pacific. Vol. 73, No. 435, 1961, pp. 462-463, bibcode : 1961PASP ... 73..462M .
  6. ^ RL Branham, Jr .: Orbit of Comet 1961 V (Wilson-Hubbard). In: The Astronomical Journal. Vol. 73, no. 2, 1968, pp. 97-98, bibcode : 1968AJ ..... 73 ... 97B .
  7. ^ 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 .
  8. ^ RL Branham, Jr .: A new orbit of Comet 1961 V (Wilson-Hubbard). In: Celestial Mechanics. Vol. 36, 1985, pp. 365-373, bibcode : 1985 CeMec..36..365B .
  9. ^ A b E. Everhart, BG Marsden: Original and future cometary orbits. III. In: The Astronomical Journal. Vol. 93, No. 3, 1987, pp. 753-754, bibcode : 1987AJ ..... 93..753E .
  10. ↑ NASA JPL Small-Body Database Browser: C / 1961 O1. Retrieved September 29, 2015 .
  11. ↑ SOLEX 11.0 A. Vitagliano. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .