C / 1885 X2 (Barnard)

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C / 1885 X2 (Barnard) [i]
Properties of the orbit ( animation )
Period:  February 1, 1886 ( JD 2,409,938.5)
Orbit type hyperbolic
Numerical eccentricity 1,00020
Perihelion 0.479 AU
Inclination of the orbit plane 84.4 °
Perihelion May 3, 1886
Orbital velocity in the perihelion 60.8 km / s
history
Explorer Edward E. Barnard
Date of discovery 4th December 1885
Older name 1886 II, 1885e
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1885 X2 (Barnard) was a comet that could be seen with the naked eye in 1886 .

Discovery and observation

Comet C / 1885 X1 (Fabry) was discovered in Paris on the evening of December 1, 1885 . By the following evening the news of this had reached the comet finder Edward E. Barnard in Nashville ( Tennessee ), who was also able to observe this comet successfully. On the following evening of December 3, 1885 (local time) the observation conditions but were initially unfavorable to this comet, and Barnard started the sky using a 15 cm - refractor scan for other comets. After two hours he found a foggy object unknown to him.

It was his fifth comet discovery and at that time the comet was still far from the sun, beyond the orbit of Mars . Nevertheless, he was already closely watched later in the month, including by Ralph Copeland in Scotland , Herbert H. Turner at the Royal Greenwich Observatory , Ladislaus Weinek in Prague , Ernst Wilhelm Leberecht Tempel in Italy and Alphonse Louis Nicolas Borrelly in Marseille . Up until February 1886, the comet made a very diffuse and faint impression, and it was not until the end of the month that a small tail began to form. At the end of March the brightness had increased to about 8 mag.

In April 1886 the comet was moving towards its closest approach to the sun and earth , but it could only be seen directly over the horizon at dusk and then appeared at dawn from the end of the month . The brightness had now reached about 5.5 mag and the tail a length of 2 ° .

In the first half of May the comet was also observed with the naked eye by several observers who reported a magnitude of 5 and a tail length of 3 °. Barnard made the last observation in the northern hemisphere on May 17th. After making its closest approach to the Sun, the comet moved rapidly south in the sky and was followed by a few observers in the southern hemisphere from the end of the month , including William Henry Finlay at the Royal Observatory on the Cape of Good Hope and John Tebbutt in Windsor (New South Wales) in Australia . Tebbutt could still see it with the naked eye on June 3, but it moved away quickly and faded, and the last observation was finally made on July 26, 1886.

During the same period in which Comet Barnard could be observed, Comet Fabry, which had been discovered almost 2½ days earlier, was visible in the sky, which appeared a little brighter for most of the time. On the evening of April 24, 1886, the two comets approached each other to within 7 °.

Scientific evaluation

As a comet with a secured hyperbolic orbit , Comet Barnard attracted the interest of astronomers who investigated the possible interstellar origin of the comets. In particular, attempts were made to calculate the orbital elements of the comets backwards in order to check whether the shape of the orbit had changed when it passed through the inner solar system .

The first who, according to his own calculations, assumed that the hyperbolic orbit of Comet Barnard had developed from a very elongated ellipse as a result of the orbital disturbances by the large planets , was the German astronomer Anton Thraen . Corresponding calculations, which confirmed this assumption, were also carried out by Louis Fabry , Gaston Fayet , Svante Elis Strömgren and George Van Biesbroeck .

Strömgren calculated a semi-major axis of about 3150 AU for the originally elliptical orbit of comet Barnard , taking into account the orbital disturbances only by Jupiter and Saturn . In a more recent study from 1978, Marsden , Sekanina and Everhart gave a similar value of about 3000 AU for the semi-major axis.

The orbital elements of comet C / 1885 X2 were used alongside those of 18 other extremely long-period comets by Jan Hendrik Oort to derive his hypothesis of the Oort comet cloud .

Orbit

For the comet, a very precise hyperbolic orbit could be determined from 56 observations over a period of 150 days, which is inclined by around 84 ° to the ecliptic . The comet's orbit is thus almost perpendicular to the planets' orbital plane. At the point of the orbit closest to the sun ( perihelion ), which the comet passed on May 3, 1886, it was located at about 71.7 million km from the sun in the area between the orbits of Mercury and Venus . On May 9th it passed Mercury at a distance of 70.0 million km and on May 14th it passed Venus at a distance of 75.7 million km. Its closest approach to earth took place on May 27, at a distance of about 0.34 AU / 50.1 million km. This relatively close passage was the reason for its observed brightness.

Some time before its approach to the inner solar system in 1886, the comet was still moving on an extremely elongated elliptical orbit with an orbital eccentricity of about 0.99975 and a semiaxial major axis of about 2450 AU. It thus had an orbital period of about 120,000 years and had probably only come close to the sun a few times before. Due to the gravitational pull of the planets , especially when passing Saturn on August 28, 1884 and Jupiter on May 31, 1886 at a distance of about 5 AU, the eccentricity of its orbit was increased to a value of about 1.00003, so that it is now removed on a hyperbolic orbit. The comet will therefore no longer return to the inner solar system.

See also

Individual evidence

  1. ^ W. Sheehan: The Immortal Fire Within: The Life and Work of Edward Emerson Barnard . Cambridge University Press, Cambridge 1995, ISBN 0-521-44489-6 , pp. 80-81.
  2. ↑ GW Kronk: Cometography - A Catalog of Comets, Volume 2. 1800-1899 . Cambridge University Press, Cambridge 2003, ISBN 0-521-58505-8 , pp. 561-566.
  3. ↑ Illustrated Yearbook of Natural History. Volume 10, Teschen 1912, quoted by F. Neureuter in: Unser Eichsfeld. Journal of the Association for Eichsfeldische Heimatkunde. 8th volume, Heiligenstadt 1913, pp. 59-60 ( Link ).
  4. ↑ G. Abetti, WE Bernheimer, K. Graff, A. Kopff, SA Mitchell (Ed.): Handbuch der Astrophysik. Vol. IV The solar system . Springer, Berlin, Heidelberg 1929, ISBN 978-3-662-38835-8 , pp. 429-430 doi: 10.1007 / 978-3-662-39753-4 .
  5. ^ E. Strömgren, B. Strömgren: Textbook of Astronomy . Springer, Berlin 1933, ISBN 978-3-642-89464-0 , pp. 310-311 doi: 10.1007 / 978-3-642-91320-4 .
  6. ^ 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 .
  7. ^ JH Oort: The Structure of the Cloud of Comets Surrounding the Solar System, and a Hypothesis Concerning Its Origin. In: Bulletin of the Astronomical Institutes of the Netherlands. Vol. 11, No. 408, 1950. pp. 91-110, bibcode : 1950BAN .... 11 ... 91O .
  8. ^ PA Dybczyński: On the famous Oort table. Retrieved September 11, 2015 .
  9. ↑ C / 1885 X2 (Barnard) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt
  10. ↑ SOLEX 11.0 A. Vitagliano. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .