C / 1976 D1 (Bradfield)

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C / 1976 D1 (Bradfield) [i]
Properties of the orbit ( animation )
Period:  March 3rd, 1976 ( JD 2,442,840.5)
Orbit type long-period
Numerical eccentricity 0.9938
Perihelion 0.848 AU
Aphelion 273 AU
Major semi-axis 137 AU
Sidereal period ~ 1600 a
Inclination of the orbit plane 46.8 °
Perihelion February 24, 1976
Orbital velocity in the perihelion 45.7 km / s
history
Explorer WA Bradfield
Date of discovery 19th February 1976
Older name 1976 IV, 1976a
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1976 D1 (Bradfield) is a comet which in 1976 could only be observed with optical aids.

Discovery and observation

The comet was on the evening of February 19, 1976 (local time) by William A. Bradfield in Australia with a mm 150 - f / 5.5 - Refractor discovered. It was his fifth comet discovery, just three months after his last. During this period he had searched for comets for a total of 57 hours. Bradfield estimated the comet's brightness to be about 9 mag. The discovery was confirmed by several other observers the next day.

Shortly after its discovery, the comet could also be observed from the northern hemisphere . It did not become much brighter than when it was discovered; in April its brightness had already decreased again. The last observation was on May 28, 1976.

Orbit

For the comet, from 32 observation data over a period of 97 days, Marsden was able to determine an elliptical orbit with limited accuracy , which is inclined by around 47 ° to the ecliptic . At the point of the orbit closest to the sun ( perihelion ), which the comet passed on February 24, 1976, it was at 126.8 million km from the sun in the area between the orbits of Venus and Earth . On March 20, it approached Mars to within 138.5 million km and on March 21, it came to within about 0.41  AU / 61.9 million km.

The comet moves in an extremely elongated elliptical orbit around the sun. According to the orbital elements afflicted with a certain uncertainty, its orbit some time before the passage of the inner solar system in 1976 had an eccentricity of about 0.9916 and a semi-major axis of about 100 AU, so that its orbital period was about 995 years. The comet could therefore last have appeared in the Middle Ages around the year 980. Due to the gravitational pull of the planets, especially a very close passage of Jupiter on December 23, 1974 at a distance of only about 1 ⅓ AU, the orbital eccentricity was increased to about 0.9938 and the semi-major axis to about 138 AU, so that its orbital period is increased to now increased for about 1622 years. When it reaches the point of its orbit furthest from the sun ( aphelion ) around the year 2785 , it will be 41.2 billion km from the sun, over 275 times as far as the earth and over 9 times as far as Neptune . Its orbital speed in the aphelion is only about 0.14 km / s. The comet's next perihelion is expected to take place around the year 3600.

Meteor shower

It was subsequently possible to calculate that on February 29, 1976 the earth was in the vicinity of the ascending node of the orbit of comet C / 1976 D1, at a distance of only 0.017 AU / 2.5 million km.

Dust left behind by the comet on its orbit could therefore cause a meteor shower on Earth every year around March 1st . The meteors would appear for about an hour from a starting point near the star β Tucanae and would only be visible from the southern hemisphere . A particularly favorable situation for observing the meteor shower of the β-Tucanids was expected for March 1, 2003. However, only one meteor was observed on an observation mission in South Africa and it is therefore not yet certain whether this meteor shower even exists.

The next favorable opportunities to observe the meteor shower of the β-tucanids arise in the years 2021 and 2032.

See also

Web links

Individual evidence

  1. ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Retrieved December 18, 2015 .
  2. ^ 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. 498-500.
  3. ^ BG Marsden, DWE Green, E. Roemer: Comets in 1976. In: Quarterly Journal of the Royal Astronomical Society. Vol. 26, 1985, pp. 68-80 ( bibcode : 1985QJRAS..26 ... 68M ).
  4. ↑ NASA JPL Small-Body Database Browser: C / 1976 D1 (Bradfield). Accessed December 23, 2015 .
  5. ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .
  6. ^ 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 ).
  7. ^ IAU Central Bureau for Astronomical Telegrams - IAUC 2933: 1976a. Accessed December 22, 2015 .
  8. ^ IAU Central Bureau for Astronomical Telegrams - IAUC 8079: 2003ax, 2003ay; Poss. Meteors from C / 1976 D1; C / 2002 Y1. Accessed December 22, 2015 .
  9. ↑ NASA Science News: A Rare Meteor Shower. Retrieved April 3, 2018 .
  10. ↑ P. Jenniskens: Meteor Showers and their Parent Comets. Cambridge University Press, Cambridge 2006, ISBN 978-0-521-85349-1 , p. 85.
  11. ↑ P. Jenniskens: Meteor Showers and their Parent Comets. Cambridge University Press, Cambridge 2006, ISBN 978-0-521-85349-1 , p. 617.