C / 1885 X1 (Fabry)

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C / 1885 X1 (Fabry) [i]
Properties of the orbit ( animation )
Period:  January 18, 1886 ( JD 2,409,924.5)
Orbit type hyperbolic
Numerical eccentricity 1,00036
Perihelion 0.642 AU
Inclination of the orbit plane 82.6 °
Perihelion April 6, 1886
Orbital velocity in the perihelion 52.6 km / s
history
Explorer Louis Fabry
Date of discovery December 1, 1885
Older name 1886 I, 1885d
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1885 X1 (Fabry) was a comet that could be seen with the naked eye in 1886 .

Discovery and observation

On the evening of December 1, 1885, the comet was discovered by Louis Fabry in Paris . At that time, the comet was still far from the sun , beyond the orbit of Mars . It appeared with a brightness of about 12 mag and slowly moved west in the sky in the following days.

He was closely watched later in the month, including by Ernst Wilhelm Leberecht Tempel in Italy , Ralph Copeland in Scotland , Julius Bauschinger in Munich and Ladislaus Weinek in Prague . Although the comet continued to approach the sun, it moved away from the earth again in the following weeks , so that its brightness increased only slowly. By the end of January 1886 it had reached 6 mag and the distance to the earth began to decrease again afterwards. From the end of February the formation of a small tail could also be observed.

The comet continued to approach Earth through March and April. By the end of April its brightness had grown to about 2 mag. At dawn on May 26th and 27th, the comet was observed for the last two times from the northern hemisphere with a narrow tail 10 ° in length and just one day later it passed the sun at a distance of about 9 °. Chinese astronomers also reported a "broom star" in May 1886.

The comet was then rediscovered from the southern hemisphere as early as dusk on May 1st . a. from South Africa and Brazil . The brightness and length of the tail decreased rapidly due to the increasing distance from the sun and earth, and the last observation was made on July 30, 1886, when the comet was already moving beyond the orbit of Mars .

During about the same period in which Comet Fabry could be observed, Comet C / 1885 X2 (Barnard), discovered almost 2½ days later, was visible in the sky, but most of the time it appeared a little weaker. 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 Fabry attracted the interest of astronomers who were studying 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 .

For comet Fabry, a calculation by Svante Elis Strömgren , taking into account the orbital disturbances only from Jupiter and Saturn , still resulted in a slightly hyperbolic initial situation, but the deviation from an elliptical orbit was within the uncertainty of the original orbit determination.

In a more recent study from 1978, Marsden , Sekanina and Everhart found a hyperbolic shape for the original orbit, but here too the orbital eccentricity was very close to 1, and an originally elliptical orbit was considered likely if non-gravitational influences were also taken into account would have been.

In a study from 2010, Królikowska and Dybczyński proved that significant statements about the original and future orbit of the comet can only be made if, in addition to the gravitational disturbances from all planets and the relativistic effects , there are also non- gravitational influences are taken into account in the calculation. The orbit elements determined by them from 228 observations over a period of 142 days therefore also contain two non-gravitational parameters. To assess the comet's past and future orbit, the differential tidal forces from the center and disk of the galaxy on the sun and comet were also taken into account. The calculations confirm the assumption of an originally elliptical orbit shape of the comet, as well as the now hyperbolic orbit shape.

The orbital elements of comet C / 1885 X1 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

A first parabolic orbit was calculated for the comet just a few days after its discovery , but soon an unusual difficulty became apparent in determining the probable date of the passage of the sun, as several calculations provided widely differing data. Only when the orbital data from December 1885 to June 1886 was taken into account was it recognized for the first time in the following year that the comet was moving on a hyperbolic orbit.

For the comet, a very precise hyperbolic orbit could be determined from 26 observations over a period of 142 days, which is inclined by around 83 ° 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 April 6, 1886, it was located at a distance of 96.1 million km from the sun in the area between the orbits of Mercury and Venus . On April 17th it passed Mercury at a distance of 52.4 million km and on April 18 it passed Venus at a distance of 68.0 million km. Its closest approach to earth took place on May 1st at a distance of about 0.20 AU / 29.6 million km. This relatively close passage was the reason for its observed brightness. On May 12, there was another passage on Mars at a distance of 136.5 million km.

The following statements are based on the non-gravitational orbital elements of Królikowska and Dybczyński. 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 0.99996 and a semiaxial major axis of about 16,000 AU. It thus had an orbital period in the order of 2 million years and had come close to the Sun at least once before, so it was definitely not a "dynamically new" comet. However, due to the gravitational pull of the planets , especially when passing Saturn on August 23, 1883 in 6 AU and on Jupiter on May 21, 1886 in just 5 AU, the eccentricity of its orbit was increased to a value of about 1.00007, so that he is now moving away on a hyperbolic orbit. The comet will therefore almost certainly not return to the inner solar system.

See also

Individual evidence

  1. ↑ GW Kronk: Cometography - A Catalog of Comets, Volume 2. 1800-1899 . Cambridge University Press, Cambridge 2003, ISBN 0-521-58505-8 , pp. 553-561.
  2. ^ 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 .
  3. ↑ 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 .
  4. ^ 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 .
  5. ^ Solar System Dynamics & Planetology Group: C / 1885 X1 Fabry. Retrieved September 15, 2015 .
  6. ↑ a b M. Królikowska, PA Dybczyński: Where do long-period comets come from? 26 comets from the non-gravitational Oort spike. In: Monthly Notices of the Royal Astronomical Society. Vol. 404, 2010, pp. 1886-1902 doi: 10.1111 / j.1365-2966.2010.16403.x PDF; 9.4 MB .
  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 X1 (Fabry) in the Small-Body Database of the Jet Propulsion Laboratory (English).
  10. ↑ SOLEX 11.0 A. Vitagliano. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .