C / 1927 X1 (Skjellerup-Maristany)

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C / 1927 X1 (Skjellerup-Maristany) [i]
Properties of the orbit ( animation )
Epoch:  December 26, 1927 ( JD 2,425,240.5)
Orbit type long-period
Numerical eccentricity 0.99984
Perihelion 0.176 AU
Aphelion 2202 AE
Major semi-axis 1101 AE
Sidereal period ~ 36,500 a
Inclination of the orbit plane 85.1 °
Perihelion December 18, 1927
Orbital velocity in the perihelion 100.4 km / s
history
Explorer JF Skjellerup , E. Maristany et al. a.
Date of discovery November 27, 1927
Older name 1927 IX, 1927k
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1927 X1 (Skjellerup-Maristany) was a comet that could be seen with the naked eye during the day in 1927 and 1928 . Due to its extraordinary brightness, it is counted among the " Great Comets ".

Discovery and observation

Few bright comets in history have stood as unfavorably in the sky as this one. It has theoretically been shown that the geometrical conditions for the visibility of a comet can be such that its observation becomes impossible. This comet was close to this worst of all cases. If it hadn't turned out so extraordinarily bright, it could easily have been overlooked in the short time it had appeared.

The comet was first noticed by at least 10 people in the morning sky of November 27, 1927. It is impossible to say how many independent and undetected discoveries there were in late November and early December. One of the first discoveries was made in New Zealand on November 28th, but news of this was unfortunately delayed. The first report that reached the relevant authorities was from John Francis Skjellerup , a South African who was living in Melbourne at the time and had found the short-period comet 26P / Grigg-Skjellerup five years earlier . His discovery was a godsend as he had no intention of looking for comets. He was rudely woken up early in the morning by a noise because a cat had knocked something over. When he found that the sky was clear, he wanted to take the opportunity and quickly found the new comet.

The next morning there was another independent discovery by an observer in New Plymouth and then another by Edmundo Maristany in La Plata on December 6th. At that time the comet had already reached a magnitude of 2 mag and had a tail 3 ° long. Due to its strong southern declination , the comet could be seen in both the morning and evening skies in early December, but only low over the horizon at dusk . It appeared as a brightly glittering yellow object with a pale yellow tail that widened towards the end.

At the time of its perihelion , the comet stood north and very close to the sun for a short time and could then also be observed from the northern hemisphere . On the morning of December 15, the comet was discovered by chance during a solar observation at the Kodaikanal solar observatory in India ; further observations were made on the following days in Hanover and at the observatories in Bergedorf , Sonneberg , Potsdam , Yerkes , Wellesley and Harvard , as brightnesses of 1 mag and tail lengths of 8 ° have been reported.

On these few days around the middle of December, the comet was a conspicuous object and could often be observed in the daytime sky. Skjellerup himself could see him only 2 ° from the sun on December 15th. The comet became brighter than the Great January Comet C / 1910 A1 and reached at least –6 mag on December 16. It was therefore also brighter than the Große Sonnenstreifer C / 1843 D1 , C / 1882 R1 and C / 1965 S1 (Ikeya-Seki) . This extreme brightness was not only due to its short perihelion distance, but also to the effect of the forward scattering of sunlight by the ice and dust particles around the comet's core when it stood almost between the sun and earth. Just two days later, the brightness had already dropped to around –1 mag and on December 20, the last observation of the daytime sky was only possible with a telescope .

Soon after, the comet was again south of the sun and the brightness quickly decreased. On the last days of December and the first days of January, however, tail lengths of up to 35 ° were reported. The tail observations on January 3, 1928 were the last sightings of the comet with the naked eye, during February the brightness dropped from 9 to 10 mag and the last sighting took place on April 28 in Johannesburg .

The comet reached a magnitude of 1 mag on December 8th. According to other information, the maximum brightness reached -6 mag.

Scientific evaluation

On December 16, the comet was spotted in the daytime sky by a forest worker in Flagstaff , who reported his observation to the Lowell Observatory , which apparently had previously received no information about the comet. Carlotto Lampland put then in the following days for the first time ever measurements of a comet in infrared light on by a he him in the day sky radiometer through a 42- inch - reflecting telescope surveyed. Not until comet C / 1965 S1 (Ikeya-Seki) were observations made again in the infrared.

Due to the strong forward scattering of sunlight in the dust of the comet's envelope during the time the comet passed between the sun and earth, the continuum in the comet's spectrum covered all emission lines that might have been seen. This spectroscopic behavior was similar to that of January comet C / 1910 A1. As with this one, strong sodium lines could be seen a few days later.

Orbit

Orbit elements calculated shortly after the appearance of the comet were initially interpreted to mean that it could be a return of comet 122P / de Vico from 1846. This later proved to be a false assumption.

Brian Marsden was able to determine an elliptical orbit for the comet from 34 observation data over a period of 115 days , which is inclined by around 85 ° to the ecliptic . The comet thus runs in an orbit that is almost perpendicular to the planets of the planets. At the point of the orbit closest to the sun ( perihelion ), which the comet passed on December 18, it was located at a distance of about 26.4 million km from the sun, well within the orbit of Mercury . Already on December 12th, the closest approach to Earth was 0.75 AU / 112.1 million km away, and on December 14th it had reached the smallest distance to Venus with 97.5 million km . On December 31, the comet passed Mercury at a distance of 38.6 million km, and on February 6, 1928, it passed through Mars in an exceptionally close manner at a distance of only 28.6 million km.

The comet moves on an extremely elongated elliptical orbit around the sun that is almost perpendicular to the ecliptic . According to the orbital elements , which are afflicted with a certain uncertainty, its orbit before its passage through the inner solar system in 1927 still had an eccentricity of about 0.99970 and a semi-major axis of about 600 AU, so that its orbit was about 15,000 years. Due to the gravitational pull of the planets, however, its orbital eccentricity was increased to around 0.99984 and its semi-major axis to over 1100 AU, so that its orbital time more than doubled. Accordingly, it may not return to the inner solar system for 36,500 years.

See also

Individual evidence

  1. ^ G. van Biesbroeck: Comet Notes. Comet 1927k (Skjellerup-Maristany). In: Popular Astronomy. Vol. 36, 1928, p. 117 ( bibcode : 1928PA ..... 36..117V ).
  2. ^ J. Hartmann: Comet Skjellerup-Maristany. In: Astronomical News. Vol. 231, 1928, Col. 413-416 ( bibcode : 1928AN .... 231..413Z ).
  3. ^ A b D. AJ Seargent: The Greatest Comets in History: Broom Stars and Celestial Scimitars . Springer, New York 2009, ISBN 978-0-387-09512-7 , pp. 146-151.
  4. ^ Peter Grego: Blazing a Ghostly Trail: ISON and Great Comets of the Past and Future . Springer, Cham 2013, ISBN 978-3-319-01774-7 , pp. 130-133.
  5. ^ Donald K. Yeomans: NASA JPL Solar System Dynamics: Great Comets in History. Retrieved September 19, 2014 .
  6. ^ P. Moore, R. Rees: Patrick Moore's Data Book of Astronomy . Cambridge University Press, Cambridge 2011, ISBN 978-0-521-89935-2 , p. 271.
  7. ↑ JN Marcus: Another Unsung Lowell Observatory Achievement: The First Infrared Observation of a Comet. In: ASP Conference Proceedings. Vol. 471. Astronomical Society of the Pacific, San Francisco 2013, p. 181. ( arxiv : 1301.7269 ).
  8. ↑ Maud W. Makemson: Concerning the Identification of Comet Skjellerup-Maristany. In: Popular Astronomy. Vol. 36, 1928, pp. 284-286 ( bibcode : 1928PA ..... 36..284M ).
  9. ↑ Skjellerup-Maristany 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 .