C / 1979 Y1 (Bradfield)

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C / 1979 Y1 (Bradfield) [i]
Properties of the orbit ( animation )
Epoch:  January 25, 1980 ( JD 2,444,263.5)
Orbit type long-period
Numerical eccentricity 0.988
Perihelion 0.545 AU
Aphelion 90.0 AU
Major semi-axis 45.3 AU
Sidereal period ~ 304 a
Inclination of the orbit plane 148.6 °
Perihelion December 21, 1979
Orbital velocity in the perihelion 56.9 km / s
history
Explorer WA Bradfield
Date of discovery December 24, 1979
Older name 1979 X, 1979l
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1979 Y1 (Bradfield) is a comet that could be seen with the naked eye around the turn of the year 1979/80 .

Discovery and observation

The comet was on the morning of December 25, 1979 (local time) by William A. Bradfield in Australia with a 150 mm - f / 5.5 - Refractor discovered. It was his tenth comet discovery, exactly six months after his last. During this period he had searched for comets for a total of 67 hours. Bradfield estimated the comet's brightness to be 5 mag. A tail 1 ° long could already be observed.

At the time of its discovery, the comet was already moving away from the sun , but it was moving even closer to the earth . Its brightness therefore increased in the following weeks, at the beginning of January it reached 4 mag with a tail length of 4 °. Up until then, the comet could only be seen in the southern hemisphere . From the end of January 1980 it could also be seen in the northern hemisphere with decreasing brightness . At the beginning of March the brightness had dropped to about 10 mag, the last observation was made on March 17th.

Scientific evaluation

Due to its relatively close passage to the earth, the comet could be measured photometrically at several observatories in the southern and northern hemisphere from December 28, 1979 to March 10, 1980 , while it initially moved from 0.57 AU to 1.65 AU removed from her. There were thereby filter used specifically the emission lines of different compounds, including CN, C 2 , C 3 , OH and NH let through. It was possible to derive production rates of these compounds depending on the distance from the sun. In addition, an unusually large ratio between gas and dust could be determined, so that Comet Bradfield appeared to be one of the most gas-rich comets ever observed, comparable to Comet 2P / Encke .

On January 29, 1980, the comet was observed at ESO's La Silla Observatory in Chile in infrared light in the wavelength range 610–1100 nm. In the emission spectrum obtained , which was similar to that of comet C / 1969 T1 (Tago-Sato-Kosaka) , the lines of O, NH 2 , CN and C 2 could be detected.

After extensive spectroscopic examinations in the ultraviolet were carried out for the first time a few years earlier on comet C / 1975 V1 (West) , similar examinations were also carried out on comet Bradfield between the beginning of January and the beginning of March 1980 with the International Ultraviolet Explorer . The emission lines of H, O, C, S, CS, CO 2 + and OH were detected in the wavelength range from 120–320 nm . As in the visual spectrum, no lines of CO + could be found. The results of observing the emission lines of H, O and OH indicated that all of these radicals were likely caused by the decay of water . The production rate of water depending on the distance from the sun could be derived from this. It also supported the assumption that the comet's core consists mainly of water ice .

At the end of January / beginning of February 1980, the Nançay radio telescope was used to observe the 18 cm OH emission line at comet Bradfield. Only a weak signal was found.

The interaction of the comet's plasma with the solar wind can produce X-rays . On February 5, 1980, the Einstein Observatory at Comet Bradfield was searched for it, but without success. Only at comet C / 1996 B2 (Hyakutake) was it possible to detect strong X-rays with ROSAT .

On February 6, 1980, there was a rapid wave-like movement in the comet's plasma tail, which attracted a great deal of attention in specialist circles. An analysis of the data from several space probes , especially the data from Helios 2 , and from geophysical observatories on Earth could link this event to a strong fluctuation in the solar wind , which was caused by a flare on the sun three days earlier.

It has been assumed since 1949 that several comets known at the time with similar aphelion distances of around 85  AU and orbital times between 235 and 300 years form a separate comet family, as do the known families, each associated with the planets Jupiter and Saturn , Uranus and Neptune stand. Until 1991, the comet Bradfield was counted among the now grown to 10 members of the trans plutonic comet family and it was at that time trying to estimates of size, mass, brightness and current location of the hypothetical Planet X to make.

Orbit

An elongated elliptical orbit could be determined for the comet from 112 observation data over a period of 75 days , which is inclined by around 149 ° to the ecliptic . It thus runs in the opposite direction (retrograde) like the planets through its orbit. At the point of the orbit closest to the sun ( perihelion ), which the comet last traversed on December 21, 1979, it was located at a distance of 81.6 million km from the sun in the area between the orbits of Mercury and Venus . On November 19, it had already approached Venus up to around 28.3 million km and on December 20, it had come closest to Mercury with a distance of around 44.1 million km. On January 24, 1980, it passed Mars at a distance of about 133.9 million km , and on January 25, it came unusually close to Earth to about 0.20 AU / 29.6 million km.

The comet moves in an elongated elliptical orbit around the sun. In two earlier studies, parameters for the comet's original and future orbit were derived. According to the latest orbital elements , which are afflicted with a certain uncertainty, its orbit had an eccentricity of about 0.988 and a semi-major axis of about 44.2 AU, so that its orbit was about 294 years before its passage through the inner solar system in 1979/80 . It could have appeared as early as 1686 ( uncertainty ± 3.5 years). Due to the gravitational pull of the planets, in particular due to the passage of Jupiter on June 4, 1976 at a distance of about 9 ¾ AU and on February 2, 1980 at a distance of about 4 ⅔ AU, its orbital eccentricity remained almost unchanged, while its semi-major axis was slightly at about 45.2 AE was enlarged so that its orbital period increased to about 304 years. When it reaches the point of its orbit furthest from the sun (aphelion) around the year 2131 (uncertainty ± 2.1 years), it will be about 13.5 billion km from the sun, almost 90 times as far as the earth and three times as far as Neptune. Its orbital speed in aphelion is only about 0.34 km / s. The next perihelion of the comet will possibly take place around the year 2283 (uncertainty ± 3.7 years).

Meteor shower

In the vicinity of the descending node of its orbit, the comet C / 1979 Y1 moved in the immediate vicinity of the earth's orbit, at a distance of only 0.067 AU / 10.1 million km. It has therefore been suggested that the comet was the source of the weak meteor shower of the July pegasids , which occurs around July 9th every year. This could be confirmed by observations in the years 2008 to 2011.

Reception in the media

On March 7, 1986, on the occasion of the return of Halley's Comet, a special stamp for 300 francs was issued in the Comoros with a digitally post-processed image of a comet and the inscription "Comète de Bradfield 1980". Perhaps the picture shown is comet C / 1979 Y1, the main visibility of which fell in 1980, but comet C / 1980 Y1 would also be possible .

See also

Web links

Individual evidence

  1. ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Retrieved January 14, 2016 .
  2. ^ BG Marsden: Comets in 1979. In: Quarterly Journal of the Royal Astronomical Society. Vol. 26, 1985, pp. 106-114 ( bibcode : 1985QJRAS..26..106M ).
  3. ^ BG Marsden: Comets in 1980. In: Quarterly Journal of the Royal Astronomical Society. Vol. 26, 1985, pp. 156-167 ( bibcode : 1985QJRAS..26..156M ).
  4. ^ MF A'Hearn, RL Millis, PV Birch: Comet Bradfield 1979 X: The gassiest comet? In: The Astronomical Journal. Vol. 86, 1981, pp. 1559-1566 doi: 10.1086 / 113039 ( bibcode : 1981AJ ..... 86.1559A ).
  5. ↑ AC Danks, M. Denne field: Near-infrared spectroscopy of comet Bradfield 1979l. In: The Astronomical Journal. Vol. 86, 1981, pp. 314-317 doi: 10.1086 / 112890 ( bibcode : 1981AJ ..... 86..314D ).
  6. ↑ PD Feldman, HA Weaver, MC Festou, MF A'Hearn, WM Jackson, B. Donn, J. Rahe, AM Smith, P. Benvenuti: IUE observations of the UV spectrum of comet Bradfield. In: Nature. Vol. 286, 1980, pp. 132-135 doi: 10.1038 / 286132a0 ( PDF; 482 kB ).
  7. ^ MF A'Hearn, PD Feldman: Carbon in comet Bradfield 1979l. In: The Astrophysical Journal. Vol. 242, 1980, pp. L187-L190 doi: 10.1086 / 183429 ( bibcode : 1980ApJ ... 242L.187A ).
  8. ^ HA Weaver, PD Feldman, MC Festou, MF A'Hearn: Water production models for comet Bradfield (1979 X). In: The Astrophysical Journal. Vol. 251, 1981, pp. 809-819 doi: 10.1086 / 159525 ( bibcode : 1981ApJ ... 251..809W ).
  9. ↑ J. Crovisier, P. Colom, E. Gérard, D. Bockelée-Morvan, G. Bourgois: Observations at Nançay of the OH 18-cm lines in comets - The data base. Observations made from 1982 to 1999. In: Astronomy & Astrophysics. Vol. 393, 2002, pp. 1053-1064 doi: 10.1051 / 0004-6361: 20020673 ( PDF; 391 kB ).
  10. ↑ HS Hudson, W.-H. Ip, DA Mendis: An Einstein search for X-ray emission from Comet Bradfield (1979 l). In: Planetary and Space Science. Vol. 29, 1981, pp. 1373-1376 doi: 10.1016 / 0032-0633 (81) 90104-5 .
  11. ^ TE Cravens: X-ray Emissions from Comets. In: Science. Vol. 296, 2002, pp. 1042-1045 doi: 10.1126 / science.1070001 .
  12. ^ JC Brandt, JD Hawley, MB Niedner: A very rapid turning of the plasma-tail axis of comet Bradfield 1979l on 1980 February 6. In: The Astrophysical Journal. Vol. 241, 1980, pp. L51-54 doi: 10.1086 / 183359 ( bibcode : 1980ApJ ... 241L..51B ).
  13. ^ JF Le Borgne: Interpretation of the event in the plasma tail of comet Bradfield 1979 X on 1980 February 6. In: Astronomy and Astrophysics. Vol. 123, 1983, pp. 25-28 ( bibcode : 1983A & A ... 123 ... 25L ).
  14. ^ CH Schütte: Two New Families of Comets. In: Popular Astronomy. Vol. 57, 1949, pp. 176-182 ( bibcode : 1949PA ..... 57..176S ).
  15. ^ R. Neuhäuser, Johannes Feitzinger : Mass and orbit estimation of Planet X via a family of comets. In: Earth, Moon, and Planets. Vol. 54, 1991, pp. 193-202 doi: 10.1007 / BF00056320 ( bibcode : 1991EM & P ... 54..193N ).
  16. ↑ a b c NASA JPL Small-Body Database Browser: C / 1979 Y1 (Bradfield). Retrieved March 22, 2016 (English).
  17. ^ E. Everhart, BG Marsden: New original and future cometary orbits. In: The Astronomical Journal. Vol. 88, 1983, pp. 135-137 doi: 10.1086 / 113298 ( bibcode : 1983AJ ..... 88..135E ).
  18. ^ E. Everhart, BG Marsden: Original and future cometary orbits. III. In: The Astronomical Journal. Vol. 93, 1987, pp. 753-754 doi: 10.1086 / 114358 ( bibcode : 1987AJ ..... 93..753E ).
  19. ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .
  20. ^ IAU Meteor Data Center: 00175 JPE. Retrieved March 22, 2016 (English).
  21. ↑ P. Jenniskens: Meteor Showers and their Parent Comets. Cambridge University Press, Cambridge 2006, ISBN 978-0-521-85349-1 , p. 715.
  22. ↑ M. Ueda: Orbits of the July Pegasid meteors observed during 2008 to 2011. In: WGN, the Journal of the International Meteor Organization. Vol. 40, No. 2, 2012, pp. 59-64 ( bibcode : 2012JIMO ... 40 ... 59U ).
  23. ↑ Stamp World: Comores - Timbres-Poste (1986). Retrieved March 24, 2016 (French).