C / 1880 C1 (Great Southern Comet)

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C / 1880 C1 (Great Southern Comet) [i]
Properties of the orbit ( animation )
Epoch:  January 28, 1880 ( JD 2,407,742.6182)
Orbit type parabolic
Numerical eccentricity 1.0
Perihelion 0.00549 AU
Inclination of the orbit plane 144.7 °
Perihelion January 28, 1880
Orbital velocity in the perihelion 568 km / s
history
Explorer
Date of discovery February 1, 1880
Older name 1880 I, 1880a
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1880 C1 (Great Southern Comet ) was a comet that could be seen with the naked eye in the southern hemisphere in 1880 . Due to its extraordinary brightness, it is counted among the " Great Comets ".

Discovery and observation

On January 28, 1880, the comet had passed behind the Sun for 38 minutes from about 1:56 UT , as viewed from Earth , and reappeared on the opposite side 15 minutes after the time it was closest to the Sun. However, this event has not yet been observed.

There are only second-hand reports of the discovery of this comet, so the actual discoverer is not known. However, the reports leave no doubt that the comet was first observed in the evening sky of February 1, 1880 in New Zealand and Australia .

In the following days there were independent discoveries in several places in the southern hemisphere , including a. by Benjamin Apthorp Gould in Córdoba (Argentina) and by John Tebbutt in Windsor (New South Wales) . The comet had just passed its perihelion and was still close to the sun when it was discovered. Therefore, at first only its tail was observed, which rose 20-30 ° above the horizon and the upper part of which was curved to the south.

On February 4th, the comet's core could be seen for the first time . The narrow tail was now 40–50 ° long and no longer curved. On February 6, the comet's brightness began to decrease, but the tail reached its greatest length of 75 °. In the following nights the comet became more and more difficult to observe, from February 14th it could only be seen in the telescope . The last observation was made on February 20th by Gould.

The comet reached a brightness of 3 mag.

Scientific evaluation

Comets as close to the Sun as the Great South Comet of 1880 have puzzled astronomers for over 300 years. Ever since it was proven that the Great Comet C / 1680 V1 had almost grazed the sun's surface at a distance of only 200,000 km, they wondered, on the one hand, how comets can survive such a thing and, on the other, when such a sun streak had appeared before could.

For a long time, three or four comets from the last third of the 17th century (not the comet of 1680) were considered the most likely candidates for an earlier appearance of the Great March Comet of 1843. Values ​​of 175 years down to the completely impossible 7 years have been assumed as the orbital period of the comet. Direct calculations based on the observations of the comet showed, however, that the orbital period probably cannot be shorter than 400 to 500 years.

When the Great South Comet appeared in 1880, orbiting in almost the same orbit, proponents of a 35- to 40-year period were still having a great time. When the Great September Comet C / 1882 R1 reappeared with a very similar orbit in 1882 , it was already assumed that this sun streak would have been decelerated very strongly by friction in a solid medium surrounding the sun at each return. However, this turned out to be incorrect, as the observation data of the comet from 1882 showed an orbital period of several centuries.

The conclusion was that there must be a number of different comets moving in practically the same sun-grazing orbit. Daniel Kirkwood was the first to suggest in 1880 that the sun-grazing comets formed such a comet group. He suggested that the comets of 1843 and 1880 were fragments of the Great Comet of 373 BC. BC , which according to the report of the Greek historian Ephorus was broken into two parts. The comet of 1882 also broke into several fragments as it passed the sun. A few years later, another member of this comet group was identified with the great southern comet C / 1887 B1 .

The sun streaker was then examined very intensively from 1888 to 1901 by Heinrich Kreutz , who suspected that all members of the comet group later named after him, the Kreutz group , descended from an original body that broke when it passed the sun. He identified other possible members of the group, and further group members appeared in the 20th century in 1945, 1963, 1965 and 1970.

In 1967 Brian Marsden examined the orbits of the previously known comets of the Kreutz group and showed that their members can be divided into two subgroups according to their slightly different orbital elements . The sun streaker C / 1880 C1, together with C / 1843 D1, is one of the most important representatives of subgroup I. As a result, there have been many attempts to theoretically capture the possible decay processes and the resulting trajectories of the sun streakers, in particular by Zdenek Sekanina and others.

Marsden presented a scenario in 1989 in which the two comets C / 1843 D1 and C / 1880 C1 could be fragments of a common precursor comet that would have broken if it had passed the sun around 1487. This previous comet could again have been a fragment of the comet of −371. In this case, however, the orbital period of the comet from 1843 would only have been around 360 years, which contradicts previous knowledge. In addition, there are no reports of sun-grazing comets from the late 15th century.

In very extensive investigations, Sekanina and Paul W. Chodas developed new theories about the origin and development of the Kreutz comet group, which currently reflect the current state of knowledge. According to the model of the two super fragments, it can be assumed that all the sun streakers of the Kreutz group descend from a very large predecessor comet with a diameter of almost 100 km, which may have been in the late 4th century or early 5th century a few decades before it passed the sun has broken in two roughly equal parts. The two super fragments made one more orbit around the sun and super fragment I reappeared in 1106 as the famous sun streaker X / 1106 C1 . Superfragment II appeared only a few years earlier or later, but apparently escaped observation due to unfavorable viewing conditions as there are no reports about it. Both super fragments broke again into further fragments shortly after their extremely close passage to the sun at that time, internally damaged by the enormous tidal forces ( cascading fragmentation ): Superfragment I initially split into two further parts, the first appeared later as the comet C / 1843 D1 , the other part disintegrated two years later into the two sun streaks that appeared later as comets C / 1880 C1 and C / 1887 B1. The comet of 371 BC Chr. Had, however, as it turned out, no relation to the Kreutz group.

Orbit

For the comet, only one parabolic orbit could be determined by Kreutz from 29 observation data over a period of 14 days . The parameters are given in the info box. The following information is based on the improved orbital elements for the comet, which were assumed in 2004 by Sekanina & Chodas on the basis of theoretical considerations and using modern mathematical methods, taking into account all planetary disturbances and relativistic effects. According to this, the comet describes an extremely elongated elliptical orbit that is inclined by around 145 ° to the ecliptic . The comet thus runs in the opposite direction (retrograde) like the planets through its orbit. The value for the semi-major axis is 84.4 AU and the eccentricity 0.999934. At the point of the orbit closest to the sun ( perihelion ), which the comet traversed on January 28, 1880, it was only about 1/5 of a solar radius above its surface at a distance of 0.828 million km from the sun . By January 3, it had already approached the earth to within 0.61 AU (≈91.6 million km). About 10 hours after its perihelion passage, it passed Venus at a distance of 105.0 million km and on February 9th it approached the earth again to within 0.67 AU (≈100.8 million km).

According to the more recent studies, the comet together with C / 1887 B1 is probably a secondary fragment of the sun-grazing comet X / 1106 C1 , after which its orbital period to its last passage through the inner solar system would have been about 775 years. Under this assumption and with its unchanged existence it could reach the point furthest from the sun ( aphelion ) of its orbit around the year 2225 , where it would be about 23 billion km from the sun, almost 160 times as far as the earth and over 5 -time as far as Neptune . Its orbital speed in aphelion is only about 0.016 km / s. The next perihelion of the comet could then possibly take place around the year 2570.

However, it is much more likely that the comet, like its direct predecessors and many other members of the Kreutz group, will continue to disintegrate. Such a spontaneous decay can occur at any point in its subsequent orbit around the sun, but when the fragments return to the inner solar system depends heavily on where and when this breakup happens (or has already happened). After decay, individual fragments could have new orbital times in a wide range from ½ to several times the old orbital period and could therefore reappear sometime after the 23rd century at the earliest or only after more than a thousand years.

See also

Individual evidence

  1. ↑ a b SOLEX 11.0 by A. Vitagliano. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .
  2. ^ DAJ Seargent: The Greatest Comets in History: Broom Stars and Celestial Scimitars . Springer, New York 2009, ISBN 978-0-387-09512-7 , pp. 202-204.
  3. ^ GW Kronk: Cometography - A Catalog of Comets. Volume 2: 1800-1899 . Cambridge University Press, 2003, ISBN 0-521-58505-8 , pp. 448-452.
  4. ^ P. Moore, R. Rees: Patrick Moore's Data Book of Astronomy . Cambridge University Press, Cambridge 2011, ISBN 978-0-521-89935-2 , p. 270.
  5. ^ Daniel Kirkwood: On the Great Southern Comet of 1880. In: The Observatory. Vol. 3, No. 43, 1880, pp. 590-592 ( bibcode : 1880Obs ..... 3..590K ).
  6. ↑ BG Marsden: The Sungrazing Comet Group. In: The Astronomical Journal. Vol. 72, No. 9, 1967, pp. 1170-1183 ( bibcode : 1967AJ ..... 72.1170M ).
  7. ^ Zdeněk Sekanina: Problems of Origin and Evolution of the Kreutz Family of Sun-grazing Comets. In: Acta Universitatis Carolinae. Mathematica et Physica. Vol. 8, No. 2, 1967, pp. 33-84 ( PDF; 4.73 MB ).
  8. ↑ BG Marsden: The Sungrazing Comet Group. II. In: The Astronomical Journal. Vol. 98, No. 6, 1989, pp. 2306-221 ( bibcode : 1989AJ ..... 98.2306M ).
  9. ↑ a b Zdenek Sekanina, Paul W. Chodas: Fragmentation Hierarchy of Bright Sungrazing Comets and the Birth and Orbital Evolution of the Kreutz System. I. Two-Superfragment Model. In: The Astrophysical Journal. Vol. 607, 2004, pp. 620-639, doi: /10.1086/383466 .
  10. ↑ Zdenek Sekanina, Paul W. Chodas: Fragmentation Hierarchy of Bright Sungrazing Comets and the Birth and Orbital Evolution of the Kreutz System. II. The Case for Cascading Fragmentation. In: The Astrophysical Journal. Vol. 663, 2007, pp. 657-676, doi: /10.1086/517490 .
  11. ↑ C / 1880 C1 (Great Southern Comet) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt