C / 1995 Q1 (Bradfield)

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C / 1995 Q1 (Bradfield) [i]
Properties of the orbit ( animation )
Period:  August 31, 1995 ( JD 2,449,960.5)
Orbit type long-period
Numerical eccentricity 0.9980
Perihelion 0.436 AU
Aphelion 441 AU
Major semi-axis 221 AU
Sidereal period ~ 3,280 a
Inclination of the orbit plane 147.4 °
Perihelion August 31, 1995
Orbital velocity in the perihelion 63.7 km / s
history
Explorer WA Bradfield
Date of discovery 17th August 1995
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1995 Q1 (Bradfield) is a comet that was observed in 1995.

Discovery and observation

The comet was on the evening of August 17, 1995 (local time) by William A. Bradfield in Australia with a mm 150 - f / 5.5 - Refractor discovered. It was his seventeenth comet discovery, a little over three years after his last. During this period he had searched for comets for a total of 289 hours. Bradfield estimated the comet's brightness to be about 6 mag and observed a tail over 1 ° long.

At first the comet could only be seen from the southern hemisphere , where it was so favorably positioned in the sky that it should actually have been found with telescopes as early as June and in July it should have been faintly visible to the naked eye. Its brightness increased to 5.3 mag by the end of August. After passing the sun , it quickly moved away from it and from September onwards moved almost exactly north, so that it could also be observed from the northern hemisphere , albeit with decreasing brightness. It was 6.7 mag in the second half of September and around 10.5 mag at the end of December. The comet could be observed until February 1996.

Scientific evaluation

From the end of August to the end of September 1995, observations of the 18 cm OH emission line at Comet Bradfield were made with the Nançay radio telescope . A clear signal was found, from which the production rate of the OH radical could be derived.

In November 1995 the Extreme Ultraviolet Explorer was used to search for ultraviolet radiation ( XUV ) emanating from comet C / 1995 Q1. No such radiation was detected.

Orbit

For the comet could from 140 observational data for a period of 173 days by Marsden an elliptical orbit are determined, which by about 147 ° against the ecliptic is inclined. 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 passed on August 31, 1995, it was located at a distance of about 65.3 million km from the sun in the area between the orbits of Mercury and Venus . On July 26th it had already come close to the earth to about 0.46  AU / 68.9 million km and on August 25th it had approached Mercury to about 31.4 million km. On September 8th, it passed Venus at a distance of about 36.5 million km.

The comet moves in an extremely elongated elliptical orbit around the sun. Based on the currently known orbital elements , its orbit some time before its passage through the inner solar system in 1995 still had an eccentricity of about 0.9985 and a semi-major axis of about 224 AU, so that its orbital period was about 3350 years. Due to the gravitational pull of the planets, especially due to the relatively close passages of Saturn on April 16, 1994 in about 4 ½ AU and on August 15, 1998 in about 5 ¾ AU, and on Jupiter on August 7, 1995 in about 4 ¾ AU and on January 27, 1999 at a distance of about 9½ AU, its orbital eccentricity was reduced to about 0.9977 and its semi-major axis to about 189 AU, so that its orbital period was shortened to about 2600 years. When it reaches the point of its orbit furthest from the sun ( aphelion ) around the year 3300 , it will be about 57 billion km from the sun, 380 times as far as the earth and almost 13 times as far as Neptune . Its orbit speed in the aphelion is only 0.06 km / s. The comet's next perihelion is expected to occur around the year 4600.

See also

Web links

Individual evidence

  1. ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Retrieved March 3, 2016 .
  2. ^ JD Shanklin: The comets of 1995. In: Journal of the British Astronomical Association. Vol. 110, No. 6, 2000, pp. 311-322 ( bibcode : 2000JBAA..110..311S ).
  3. ↑ 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 ).
  4. ^ DWE Green: IAUC 6667: 1997cn; Comets 6P / D'Arrest and C / 1995 Q1 (Bradfield); C / 1995 O1. May 22, 1997, accessed March 3, 2016 .
  5. ↑ NASA JPL Small-Body Database Browser: C / 1995 Q1 (Bradfield). Retrieved March 3, 2016 .
  6. ↑ SOLEX 11.0 A. Vitagliano. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .