C / 1980 E1 (Bowell)

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C / 1980 E1 (Bowell) [i]
Properties of the orbit ( animation )
Epoch:  January 3, 1982 ( JD 2,444,972.5)
Orbit type hyperbolic
Numerical eccentricity 1.0577
Perihelion 3,364 AU
Inclination of the orbit plane 1.7 °
Perihelion March 12, 1982
Orbital velocity in the perihelion 23.3 km / s
history
Explorer Edward LG Bowell
Date of discovery March 13, 1980
Older name 1982 I, 1980 b
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1980 E1 (Bowell) is a comet that could be observed with telescopes from 1980 for a period of almost seven years . During its flight through the solar system, the comet experienced very strong influences from the forces of attraction of the planets , so that it will leave the solar system on an unusually strongly hyperbolically shaped orbit.

Discovery and observation

The American astronomer ELG Bowell from the Lowell Observatory in Arizona discovered this comet on a photographic plate that was exposed on March 13, 1980 on a 33 cm astrograph . At this point the comet was very close to Jupiter when viewed from Earth and its brightness was about 16 mag. Bowell did not check his discovery with further recordings until March 14th and 16th before reporting it. The dwarf planet Pluto had been discovered with the same telescope exactly 50 years earlier .

It was initially feared that the proximity to Jupiter would make it difficult to determine the comet's orbit, but Bowell also found the comet afterwards on a photograph taken on February 11th. Now a preliminary orbit could be determined by Brian Marsden and it was also shown that the comet was only in the line of sight next to Jupiter, but was still significantly further away from the sun than this. At the time of its discovery it was still 7.3  AU from the sun and 6.3 AU from the earth , making it the second most distant comet when it was discovered (after C / 1976 D2 (Schuster) ). His orbital inclination was lower than that of all other comets with a parabola- ready or almost ready track. The determination of the orbit also predicted that the comet would actually experience a very close passage of Jupiter in December 1980.

The comet could be observed photographically at the Kiso Observatory in Japan at the beginning of June , then it was too close to the sun for observers on earth. It was found again by its discoverer in mid-November and observed again in December in Kiso and at the Perth Observatory in Australia .

In 1981 the comet was widely observed by observatories in the southern and northern hemisphere , including the Lowell Observatory, the Mt John University Observatory in New Zealand , the Yebes Observatory in Spain , the Argentine observatory El Leoncito , as well as amateur astronomers in Japan . Its brightness increased from 14 mag to 12 mag in October; for the rest of the year the comet was too close to the sun and could not be observed.

In January 1982 the comet in England was again found visually through a telescope at dawn at a brightness of 10.5 mag. In the following months the brightness seemed to decrease again, and when the comet neared its perihelion in March it was only 12 mag. Until the end of August, when the comet was last seen, the brightness remained in the 10–12 mag range. In mid-September it was possible to take photographs again at around 14 mag, but the comet was only observed sporadically until the end of the year.

At the beginning of 1983 the comet was again close to the sun and it was not found again until dawn at the Chamberlin Observatory in Colorado in June . It was observed again and again by its discoverer, but also at the Oak Ridge Observatory in Massachusetts and the Kleť Observatory in the Czech Republic . At the beginning of October the brightness had dropped to around 17 mag.

In 1984 the comet was only observed three times, in July at Oak Ridge and in September at Lowell Observatory. Another observation at Oak Ridge on October 19 was a record for a non-periodic comet, 56 months after its discovery and 8.8 AU from the Sun.

During the first half of 1985 the comet was again too close to the Sun and it was not until early November that an observation was made at the Kitt Peak National Observatory in Arizona , followed by another in early December. At that time the comet only had a brightness of 21 mag. He was last seen on December 29th and 30th, 1986 at Kitt Peak.

From October to the beginning of December 1991, three more attempts were made with the 3.58 m New Technology Telescope at the European Southern Observatory in Chile to photograph the comet at the calculated position at a distance of almost 24 AU from the sun. This was unsuccessful, although objects down to 27.5 mag were within reach. From the observations it was possible to infer a maximum radius of the core of 5.4 km.

Scientific evaluation

As early as April 1980, at a distance of over 7 AU from the sun, a spectrum of the comet was obtained with a 2.1 m telescope at the Kitt Peak National Observatory. It showed no emission lines , but the already widespread coma indicated an active comet, the coma of which is made up of solid particles.

With the 1.5 m telescope at the Palomar Observatory in California , spectrograms of several comets were recorded in visible light, including Comet Bowell between December 1980 and May 1981 at a distance of about 5 AU from the sun. In April 1981 observations were also carried out on the 5 m telescope in the infrared . The emission lines of C 2 and NH 2 were identified.

The International Ultraviolet Explorer (IUE) recorded ultraviolet spectrograms of a large number of comets, including one from Comet Bowell in late April 1981. It already showed clear emission lines from OH , which had never been discovered before in a comet at a distance of 3.4 AU from the sun. The production rate was already very high, with CN, which was also detected, it was significantly lower.

After observing the comet for a year, Zdenek Sekanina analyzed the changing appearance of the coma and the formation of the comet's tail . He found that the tail had already started to form at a distance of 10–12 AU from the sun and that the dust particles forming it only moved away from the core at a low speed of less than 1 m / s. This could not be explained by the fact that outgassing volatile substances carried away the dust particles from the core, as is the case with other comets, but Sekanina suspected that the comet had been surrounded by a cloud of dust and small particles since the time it was formed which only pretends that the comet's nucleus is active. He also gave an estimate for the mass of these particles and for the position of the comet's axis of rotation . He recommended observing the comet further as it approaches the sun in order to gain arguments for or against his theory from the results.

Further research therefore concentrated heavily on observations of the cometary coma. Observations of the comet in visible and infrared light were evaluated with regard to the speed of propagation of the solid particles in the coma. In order to find connections between the properties of comets, dust colors, dust production rates and the mass ratios between dust and gas were determined for six comets, including Comet Bowell. Dusty comets like Comet Bowell show a reddish color compared to sunlight, but here too the color can change into blue if the mass ratio of dust to gas is reduced.

While the comet almost covered a star, it was possible to measure the absorption of starlight by the comet's coma. From this, values ​​for the mass of the coma and an estimate of the very low albedo of the dust grains could be carried out. Even after passing through the perihelion, photometric measurements were carried out in June 1982, from which it was concluded that the production of OH probably originated from large, dirty grains of ice in the cometary coma.

Leaving the solar system, the comet was observed up to a distance of 13.6 AU. He still showed an extensive coma with the same slow expansion rate as in perihelion, but the coma production decreased significantly at a distance of about 10 AU, the same distance as the production had started when approaching the sun.

Orbit

A hyperbolic orbit could be determined for the comet from 179 observation data over a period of almost seven years , which is inclined by around 2 ° to the ecliptic . The comet's orbit is roughly in the same plane as the orbits of the planets. At the point closest to the Sun ( perihelion ), which the comet passed on March 12, 1982, it was still about 503.2 million km from the Sun and was thus in the area of ​​the asteroid belt between Mars and Jupiter. Since the comet did not reach the area of ​​the inner planets, there were no noteworthy approaches to them. The closest distance to the earth was reached on June 14, 1982 with about 371.0 million km (2.48 AU).

According to the orbital elements afflicted with a certain uncertainty , as they are given in the JPL Small-Body Database and which do not take into account non-gravitational forces on the comet, the comet would have been on an elliptical orbit with a long before its passage through the inner solar system Eccentricity of about 0.99992 and a semi-major axis in the order of about 40,000 AU, so that its period of rotation would have been about 8 million years. The comet's origin was in the Oort cloud and it may have come near the sun for the first time. Due to the gravitational pull of the planets, in particular due to a relatively close passage to Saturn on April 19, 1979 in about 2 ¾ AU distance and a very close passage to Jupiter on December 9, 1980 in only about 34.2 million km (0.23 AE) distance would change its orbit to a hyperbola with an exceptionally large eccentricity of around 1.05389, so that it would leave the solar system into interstellar space .

After B. Marsden calculated orbital elements shortly after the discovery of the comet, which indicated a slight inclination of the orbit and an unusually close encounter with Jupiter, the comet attracted the interest of many researchers who studied its orbit, including Marsden and I. Hasegawa, S. Nakano and S. Yabushita, as well as L. Buffoni, M. Scardia and A. Manara, who carefully analyzed the influences of the planets on the comet's orbit. In all calculations, however, no non-gravitational forces on the comet were taken into account, which resulted in partly elliptical but also hyperbolic characteristics for the original orbit shape of the comet. It was therefore considered possible that the comet could have an interstellar origin. In the following years Marsden and Nakano calculated again and again improved orbital elements when new observational data were available.

In 2013 R. Branham calculated new orbital elements for the comet from 203 observations. Although he also carried out a purely gravitational calculation, he came to the conclusion that the comet's orbit was originally elliptical and only became hyperbolic when it passed through the inner solar system.

In a study from 2014, however, M. Królikowska was able to show, using a total of 203 observations of the comet over a period of almost seven years, that the best agreement with the observed positions of the comet is obtained, even if non-gravitational forces are used on the comet (notwithstanding its great perihelion distance) and gave a set of such orbital elements. It also determined better values ​​for the original and future orbital shape long before and after the passage through the inner solar system. It received the result that the comet, before approaching the Sun, was on an elliptical orbit with an eccentricity of about 0.99983, a semiaxial major axis of about 18,700 AU (uncertainty ± 7.3%) and an orbital period of about 2, 6 million years ago. For the future orbit, she determined a hyperbolic characteristic with an eccentricity of about 1.05373.

See also

Web links

Commons : C / 1980 E1 (Bowell)  - collection of pictures, videos and audio files

Individual evidence

  1. ^ BG Marsden: Comets in 1980. In: Quarterly Journal of the Royal Astronomical Society. Volume 26, 1985, pp. 156-167 bibcode: 1985QJRAS..26..156M . ( PDF; 181 kB )
  2. ^ BG Marsden: Comets in 1981. In: Quarterly Journal of the Royal Astronomical Society. Volume 26, 1985, pp. 300-309 bibcode: 1985QJRAS..26R.300M . ( PDF; 166 kB )
  3. ^ BG Marsden: Comets in 1982. In: Quarterly Journal of the Royal Astronomical Society. Volume 26, 1985, pp. 530-540 bibcode: 1985QJRAS..26R.530M . ( PDF; 207 kB )
  4. ^ BG Marsden: Comets in 1983. In: Quarterly Journal of the Royal Astronomical Society. Volume 27, 1986, pp. 102-118 bibcode: 1986QJRAS..27..102M . ( PDF; 398 kB )
  5. ^ BG Marsden: Comets in 1984. In: Quarterly Journal of the Royal Astronomical Society. Volume 27, 1986, pp. 590-606 bibcode: 1986QJRAS..27..590M . ( PDF; 378 kB )
  6. ^ 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. 666-670.
  7. ^ O. Hainaut, RM West, A. Smette, BG Marsden: Imaging of very distant comets: current and future limits. In: Astronomy & Astrophysics. Volume 289, 1984, pp. 311-324 bibcode: 1994A & A ... 289..311H . ( PDF; 327 kB )
  8. ^ AL Cochran, ML McCall: Spectrophotometric Observations of Comet Bowell (1980b). In: Publications of the Astronomical Society of the Pacific. Volume 92, No. 550, 1980, pp. 854-857 doi: 10.1086 / 130763 . ( PDF; 125 kB )
  9. ↑ DC Jewitt, BT Soifer, G. Neugebauer, K. Matthews, GE Danielson: Visual and infrared observations of the distant comets P / Stephan-Oterma (1980g), Panther (1980u), and Bowell (1980b). In: The Astronomical Journal. Volume 87, No. 12, 1982, pp. 1854-1866 doi: 10.1086 / 113275 . ( PDF; 1.29 MB )
  10. ^ MF A'Hearn, DG Schleicher, RL Millis, PD Feldman, DT Thompson: Comet Bowell 1980b. In: The Astronomical Journal. Volume 89, No. 4, 1984, pp. 579-591 doi: 10.1086 / 113552 . ( PDF; 1.33 MB )
  11. ↑ PD Feldman: Ultraviolet spectroscopy of cometary comae: An update. In: Advances in Space Research. Volume 4, No. 9, 1984, pp. 177-184 doi: 10.1016 / 0273-1177 (84) 90023-1 .
  12. ^ Z. Sekanina: Comet Bowell (1980b): An Active-Looking Dormant Object? In: The Astronomical Journal. Volume 87, No. 1, 1982, pp. 161-169 doi: 10.1086 / 113092 . ( PDF; 881 kB )
  13. ↑ D. Jewitt: Coma expansion and photometry of comet Bowell (1980b). In: Icarus. Vol. 60, No. 2, 1984, pp. 373-385 doi: 10.1016 / 0019-1035 (84) 90196-9 .
  14. ↑ GC Sanzovo, PD Singh, WF Huebner: Dust colors, dust release rates, and dust-to-gas ratios in the comae of six comets. In: Astronomy & Astrophysics Supplement Series. Volume 120, No. 2, 1996, pp. 301-311 doi: 10.1051 / aas: 1996294 . ( PDF; 52.53 MB )
  15. ↑ SM Larson, MF A'Hearn: Comet Bowell (1980b): Measurement of the optical thickness of the coma and particle albedo from a stellar occultation. In: Icarus. Volume 58, No. 3, 1984, pp. 446-450 doi: 10.1016 / 0019-1035 (84) 90090-3 .
  16. ↑ MS Hanner, H. Campins: Thermal emission from the dust coma of comet Bowell and a model for the grains. In: Icarus. Volume 67, No. 1, 1986, pp. 51-62 doi: 10.1016 / 0019-1035 (86) 90173-9 .
  17. ^ KJ Meech, D. Jewitt: Comet Bowell at record heliocentric distance. In: Nature. Volume 328, 1987, pp. 506-509 doi: 10.1038 / 328506a0 .
  18. ↑ C / 1980 E1 (Bowell) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt
  19. ↑ A. Vitagliano: SOLEX 12.1. Retrieved July 9, 2020 .
  20. ^ I. Hasegawa, S. Nakano, S. Yabushita: The preliminary results on the original orbit of comet Bowell (1980b). In: Monthly Notices of the Royal Astronomical Society. Volume 196, No. 1, 1981, pp. 45P-46P doi: 10.1093 / mnras / 196.1.45P . ( PDF; 64 kB )
  21. ↑ L. Buffoni, M. Scardia, A. Manara: The orbital evolution of comet Bowell (1980b). In: The Moon and the Planets. Volume 26, No. 3, 1982, pp. 311-315 doi: 10.1007 / BF00928013 . ( PDF; 214 kB )
  22. ^ RL Branham, Jr .: New Orbits for Comets C / 1960 M1 (Humason), C / 1980 E1 (Bowell), and Musings on Extrasolar Comets. In: Revista Mexicana de Astronomía y Astrofísica. Volume 49, No. 1, 2013, pp. 111-116. ( PDF; 889 kB )
  23. ^ C / 1980 E1 Bowell. In: SSDP Home Page of Near-Parabolic Comets. Solar System Dynamics & Planetology Group, 2013, accessed August 21, 2020 .
  24. ^ M. Królikowska: Warsaw Catalog of cometary orbits: 119 near-parabolic comets. In: Astronomy & Astrophysics. Volume 567, A126, 2014, pp. 1–31 doi: 10.1051 / 0004-6361 / 201323263 . ( PDF; 2.63 MB )