C / 1932 Y1 (Dodwell-Forbes)

from Wikipedia, the free encyclopedia
C / 1932 Y1 (Dodwell-Forbes) [i]
Properties of the orbit ( animation )
Epoch:  January 8, 1933 ( JD 2,427,080.5)
Orbit type long-period
Numerical eccentricity 0.972
Perihelion 1.13 AU
Aphelion 80.8 AU
Major semi-axis 40.9 AU
Sidereal period ~ 262 a
Inclination of the orbit plane 24.5 °
Perihelion December 30, 1932
Orbital velocity in the perihelion 39.3 km / s
history
Explorer AFI Forbes , GF Dodwell
Date of discovery December 15, 1932
Older name 1932 X, 1932n
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1932 Y1 (Dodwell-Forbes) is a comet that could be observed in 1932 and 1933.

Discovery and observation

The comet was on the evening of December 15 1932 by Alexander Forbes from his private observatory in Hermanus at Cape Town in South Africa with an 8-inch - Reflector discovered. It was his third comet discovery. Separately, the comet was discovered two days later on December 17th by George F. Dodwell , the Government Astronomer in Adelaide , Australia . It was his only comet discovery. Dodwell's sighting report was received by the IAU before that of Forbes , which is why the comet was given the double name Dodwell-Forbes .

Its brightness when discovered was about 10 mag. It could first be observed from the southern hemisphere with increasing brightness up to 8 mag at the end of December, but from January 1933 also from the northern hemisphere , when a tail 1 ° long was observed. The last position was determined on April 22, 1933 at the Lick Observatory in California .

Scientific evaluation

As early as 1949, an investigation suggested that comet Dodwell-Forbes could be a member of a new comet family of at least 8 comets known at the time with similar aphelion distances of around 85  AU and orbital times between 235 and 300 years. Based on the analogy to the established comet families, which are each related to the planets Jupiter , Saturn , Uranus and Neptune , the existence of a transplutonic family and a transplutonic planet was also considered probable. Under the same assumption and with the including of the comet Dodwell Forbes grown to 10 members of the trans plutonic comet family was tried in 1991, estimates of size, mass, brightness and current location of the hypothetical Planet X to make.

Orbit

An elliptical orbit could be determined for the comet from 155 observation data over a period of 125 days , which is inclined by around 25 ° to the ecliptic . At the point of the orbit closest to the sun ( perihelion ), which the comet last traversed on December 30, 1932, it was located at a distance of 169.2 million km from the sun in the area slightly outside the orbit of the earth . On January 10, 1933, it came close to Earth to within 0.93 AU / 138.9 million km.

The comet moves in an extremely elongated elliptical orbit around the sun. According to the orbital elements , which are afflicted with a certain uncertainty, its orbit had an eccentricity of about 0.9723 and a semi-major axis of about 40.7 AU some time before the passage through the inner solar system in 1932 , so that its orbit was about 260 years. The comet could therefore have last appeared around 1673, although it apparently remained undiscovered. Due to the gravitational pull of the planets, in particular by passing close by Saturn on September 29, 1929 in only a little more than 2 AU and on Jupiter on December 25, 1933 in a distance of slightly less than 3 AU, the orbital eccentricity was about 0.9720 and the size Semi-axis reduced to about 40.6 AU, so that its orbital period was shortened to about 258 years. When it reaches the point of its orbit furthest from the sun ( aphelion ) around the year 2062 , it will be 12.0 billion km from the sun, 80 times as far as Earth and over 2½ times as far as Neptune . Its orbital speed in aphelion is only about 0.56 km / s. The comet's next perihelion is expected to take place around the year 2190.

See also

Individual evidence

  1. ^ TP Cooper: A history of comet discovery from South Africa. In: Monthly Notes of the Astronomical Society of Southern Africa. Vol. 62, 2003, pp. 170-179. ( bibcode : 2003MNSSA..62..170C )
  2. ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Retrieved May 31, 2016 .
  3. ^ G. van Biesbroeck: Comet Notes. In: Popular Astronomy. Vol. 41, 1933, pp. 116-117. ( bibcode : 1933PA ..... 41..116V )
  4. ^ AD Maxwell: The Orbit of Comet 1932n. In: The Astronomical Journal. Vol. 45, 1936, pp. 65-69 doi: 10.1086 / 105331 ( bibcode : 1936AJ ..... 45 ... 65M ).
  5. ^ CH Schütte: Two New Families of Comets. In: Popular Astronomy. Vol. 57, 1949, pp. 176-182 ( bibcode : 1949PA ..... 57..176S ).
  6. ^ 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 ).
  7. ↑ C / 1932 Y1 (Dodwell-Forbes) in the Small-Body Database of the Jet Propulsion Laboratory (English).
  8. ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .