Astronomy:Comet Arend–Roland

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C/1956 R1 (Arend–Roland)
(Great Comet of 1957)
Comet Arend-Roland photographed from the Palomar Observatory on 27 April 1957
Discovery
Discovered bySylvain Arend
Georges Roland
Discovery date6 November 1956
Alternative
designations		1957h[1]
1956 III
Orbital characteristics A
Epoch9 July 1957 (JD 2436028.5)
Number of
observations		57
Orbit typeOort cloud / Hyperbolic
Perihelion0.31604 AU
Eccentricity1.000199
Inclination119.94°
Earth MOID0.239 AU
Jupiter MOID1.610 AU
Comet total
magnitude (M1)		5.4
Last perihelion8 April 1957
Next perihelionejection

Comet Arend–Roland was discovered on November 6, 1956, by Belgian astronomers Sylvain Arend and Georges Roland on photographic plates. As the eighth comet found in 1956, it was named Arend–Roland 1956h after its discoverers. Because it was the third comet to pass through perihelion during 1957, it was then renamed 1957 III.[2] Finally, it received the standard IAU designation C/1956 R1 (Arend–Roland), with the "C/" indicating that it was a non-periodic comet and the "R1" showing that it was the first comet reported as discovered in the half-month designated by "R". The last is equivalent to the period September 1–15.[3]

Observations

In November 1956, a double astrograph at the Uccle Observatory in Brussels was being used for routine investigation of minor planets. On 6 November 1956, the Belgian astronomers Sylvain Arend and Georges Roland discovered a comet on their photographic plates. At that time the comet was at visual magnitude 10, with a strong central condensation and a short tail. The early discovery of this comet allowed observing programs and equipment to be prepared well in advance.[4]

The orbital elements for this comet were computed by Michael Philip Candy, who predicted perihelion passage on 8 April 1957. As the comet was already well developed, he predicted that the object would present a prominent display during April in the northern hemisphere. In early December the comet was 2.5 AU from the Sun and 1.7 AU from the Earth. It was in the constellation Pisces until February, when it reached magnitude 7.5–8.[4]

The comet on May 4.97, 1957

During the April perihelion passage, the tail of the comet reached a length of 15° of arc. The appearance of the tail varied, with streamers on April 16 and May 5, and the tail splitting into three beams on April 29. By April 22 the comet also displayed a prominent anomalous tail (or antitail) spanning 5°. This antitail stretched out to span 12° on April 25,[5] reaching its maximal extent. The antitail had disappeared by 29 April.[6]

Following perihelion on 8 April, the comet began to fade rapidly from its maximal brightness of magnitude −1.[7] At the start of May it was measured at visual magnitude 5.46. By 8 May it had decreased to magnitude 7, well below the sensitivity limit of the unaided human eye. On 29 May it had dropped to magnitude 8.55.[8]

This was the first comet for which attempts were made to detect it at various radio frequencies. However, these efforts were unsuccessful. No comets were successfully detected in the radio band until the 1973 passage of comet Kohoutek.[9]

Comet Arend–Roland was the subject of the first edition of the BBC's long-running astronomy program The Sky at Night on 24 April 1957.[10]

Astronomer Carl Sagan relates an anecdote on page 80 of his 1980 book Cosmos about being on duty in an observatory near Chicago in 1957 when a late-night phone call from an inebriated man asked what was the "fuzzy thing" they were seeing in the sky. Sagan told the man that it was a comet (Arend–Roland). The man asked what a comet was, and Sagan answered that it was "a snowball, one mile wide". After a long pause, the man said, quoting Sagan: "Lemme talk to a real 'shtronomer!".

Properties

It was traveling on a hyperbolic orbit, that is, traveling fast enough to escape from the Solar System entirely, hence implying that it will never be seen again by earthbound observers. Observations of the comet over a period of 520 days allowed precise orbital elements to be computed. However, the distribution of the orbital elements showed a wavy pattern that suggested a non-gravitational influence. Alternatively, the comet may have originated from interstellar space rather than from the Oort cloud.[11] When an orbital solution is computed that includes non-gravitational forces that vary as the inverse square of the heliocentric distance, somewhat different values are derived (see the Marsden (1970) column in the table below).[12]

Orbital element Sekanina (1968)[11] Marsden (1970)[12]
Epoch of periastron (T) 1957 April 8.03232 ET 1957 April 8.03201 ET
Perihelion distance (q) 0.3160540 ± 0.0000008 AU 0.3160361 ± 0.0000024 AU
Inverse semi-major axis (1/a) −0.0007886 ± 0.0000045 AU−1 −0.0006377 ± 0.0000213 AU−1
Eccentricity (e) 1.0002492 ± 0.0000014 1.0002015 ± 0.0000067
Inclination (i) 119.94936° ± 0.00005° 119.94930° ± 0.00006°
Longitude of periastron (ω) 307.78084° ± 0.00004° 308.77725° ± 0.00048°
Position angle of the ascending node (Ω) 215.15900° ± 0.00006° 215.15968° ± 0.00008°

At perihelion, the comet was emitting an estimated 7.5 × 104 kg/s (83 tons/s) of dust and was releasing roughly 1.5 × 1030 gas molecules per second. It is believed that an outburst of dust occurred on April 2, six days before perihelion. The antitail was formed from particles released between February 6 and 1 March 1957.[13] Estimates of the total amount of dust released into the zodiacal cloud range from 3 × 108 to 5 × 1010 kg.[14]

References

Notes

Citations

  1. ↑ "Comet Names and Designations". http://www.icq.eps.harvard.edu/names1.html. 
  2. ↑ J. B. Kaler (2002). The Ever-changing Sky: A Guide to the Celestial Sphere. Cambridge University Press. p. 358. ISBN 978-0-521-49918-7. 
  3. ↑ "Cometary Designation System". International Astronomical Union. http://www.minorplanetcenter.org/iau/lists/CometResolution.html. 
  4. ↑ 4.0 4.1 M. J. Hendrie (1996). "The Two Bright Comets of 1957". Journal of the British Astronomical Association 106 (6): 315–330. Bibcode: 1996JBAA..106..315H. https://ui.adsabs.harvard.edu/link_gateway/1996JBAA..106..315H/ADS_PDF. 
  5. ↑ G. Larsson-Leander (1959). "Physical observations of Comet Arend–Roland (1956 h)". Arkiv för Astronomi 2: 259–271. Bibcode: 1959ArA.....2..259L. https://ui.adsabs.harvard.edu/link_gateway/1959ArA.....2..259L/ADS_PDF. 
  6. ↑ F. L. Whipple (1957). "The Sunward Tail of Comet Arend–Roland". Nature 179 (4572): 1240. doi:10.1038/1791240a0. Bibcode: 1957Natur.179.1240W. https://www.nature.com/articles/1791240a0.pdf. 
  7. ↑ "Arend-Roland, Comet". http://www.daviddarling.info/encyclopedia/A/Arend-Roland.html. 
  8. ↑ A. Wehlau; W. Wehlau (1959). "Photoelectric photometry of Comet Arend–Roland (1956h)". Astronomical Journal 64: 463–467. doi:10.1086/107974. Bibcode: 1959AJ.....64..463W. https://ui.adsabs.harvard.edu/link_gateway/1959AJ.....64..463W/ADS_PDF. 
  9. ↑ W. J. Altenhoff; F. Bertoldi; K. M. Menten; A. Sievers et al. (2002). "Radio continuum observations of Comet C/1999 S4 (LINEAR) before, during, and after break-up of its nucleus". Astronomy & Astrophysics 391 (1): 353–360. doi:10.1051/0004-6361:20020783. Bibcode: 2002A&A...391..353A. https://www.aanda.org/articles/aa/pdf/2002/31/aah3432.pdf. 
  10. ↑ "A History of The Sky at Night". 24 April 1957. http://www.bbc.co.uk/science/space/skyatnight/patrickmoore_article2.shtml. 
  11. ↑ 11.0 11.1 Z. Sekanina (1968). "A dynamic investigation of Comet Arend–Roland 1957 III". Bulletin of the Astronomical Institute of Czechoslovakia 19: 343–350. Bibcode: 1968BAICz..19..343S. https://ui.adsabs.harvard.edu/link_gateway/1968BAICz..19..343S/ADS_PDF. 
  12. ↑ 12.0 12.1 B. G. Marsden (1970). "Comets and Non-gravitational Forces. III". Astronomical Journal 75: 75–84. doi:10.1086/110945. Bibcode: 1970AJ.....75...75M. https://ui.adsabs.harvard.edu/link_gateway/1970AJ.....75...75M/ADS_PDF. 
  13. ↑ M. Finson; R. Probstein (1968). "A Theory of Dust Comets. II. Results for Comet Arend–Roland". Astrophysical Journal 154: 353–380. doi:10.1086/149761. Bibcode: 1968ApJ...154..327F. https://ui.adsabs.harvard.edu/link_gateway/1968ApJ...154..327F/ADS_PDF. 
  14. ↑ M. Fulle (1988). "Meteoroids from comets Arend–Roland (1957 III) and Seki-Lines (1962 III)". Astronomy and Astrophysics 189 (1–2): 281–291. Bibcode: 1988A&A...189..281F. https://ui.adsabs.harvard.edu/link_gateway/1988A&A...189..281F/ADS_PDF. 

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