C / 1908 R1 (Morehouse)

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C / 1908 R1 (Morehouse) [i]
Comet Morehouse on September 30, 1908 Photo by E. Barnard (1857–1923)
Comet Morehouse on September 30, 1908
Photo by E. Barnard (1857–1923)
Properties of the orbit ( animation )
Period:  November 6th, 1908 ( JD 2,418,251.5)
Orbit type hyperbolic
Numerical eccentricity 1,00065
Perihelion 0.945 AU
Inclination of the orbit plane 140.2 °
Perihelion December 26, 1908
Orbital velocity in the perihelion 43.3 km / s
history
Explorer DW Morehouse
Date of discovery September 2, 1908
Older name 1908 III, 1908c
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1908 R1 (Morehouse) is a comet that could be observed in 1908 and 1909. It was one of the most photographed comets of the early 20th century and gained some fame as a result.

Discovery and observation

The comet was discovered on September 2, 1908 by Daniel Walter Morehouse at the Yerkes Observatory on a photograph of the northern sky . The following night, another independent discovery was made by Alphonse Louis Nicolas Borrelly in Marseille . At this point in time the comet had a brightness of 9 mag and was still 2 AU from the sun . No tail could be seen visually , but the photo plate of the discovery photograph showed that the comet was very active and showed a long and conspicuous tail.

In the following weeks, the comet was therefore intensively photographed by many astronomers, including Max Wolf in Heidelberg , as well as Edward Barnard and Morehouse themselves.

The comet moved westward across the sky until mid-December, and then disappeared at dusk when it had reached a brightness just barely visible to the naked eye. During the time of its closest approach to the sun, the comet was close to the orbit of the earth , but at a point that was almost diametrically opposite the then position of the earth, as a result of which its apparent brightness was not very pronounced due to the great distance. Had the comet appeared six months earlier or later, it could have turned into an extraordinarily spectacular Great Comet for observers on Earth .

On January 2, 1909, the comet passed the sun at a distance of only 0.67 ° from Earth and could again be observed from the southern hemisphere at dawn from mid-January . In the following months it wandered high into the southern sky , where its brightness decreased again. The last observations were made in mid-May 1909.

Scientific evaluation

The development of astrophotography around the beginning of the 20th century, together with the favorable position of the comet Morehouse in the northern sky, made it possible to provide extensive material for the development of physical theories about comets through numerous photographs of the comet at short intervals. Barnard was able to acquire 350 images with the instruments of the Yerkes Observatory alone, all of which document the extraordinary appearances of the comet during its visibility period from September to December.

The comet Morehouse was characterized in particular by the development of a tail that was very pronounced in relation to the coma . The tail was characterized by dynamically developing cloudy condensations, tail rays, waves and spiral twists that changed within a night or even every hour. Several times it could even be observed that the tail was "torn off" from the head and then a new tail was formed again starting from the head. The dynamics of these phenomena were later examined by Nicholas Theodore Bobrovnikoff .

Striking parabolic envelopes could also be observed around the actual cometary coma, which Arthur Stanley Eddington studied in detail. He was able to trace its origin back to the material of the comet's nucleus , which was ejected like a fountain in the direction of the solar radiation ("fountain theory") and then deflected in an arc in the direction of the tail by the radiation pressure of the sun. This led to the appearance of a parabolic shell, which then merged into the outer boundaries of the dust tail. The unrealistically high values ​​for the ejection speed of the material from the core and the acceleration due to the radiation pressure assumed by Eddington (reluctantly but without a better alternative) to describe the phenomenon could be determined as unnecessary in later investigations, taking into account the rotation of the comet's core.

The light of the comet was intensively examined spectroscopically , u. a. by William Wallace Campbell and Sebastian Albrecht at the Lick Observatory , Johannes Franz Hartmann at the Astrophysical Observatory Potsdam , Aymar de La Baume Pluvinel and Fernand Baldet at the observatory in Juvisy-sur-Orge , Henri-Alexandre Deslandres and A. Bernard at the Paris Observatory , Edwin Brant Frost and John Adelbert Parkhurst at the Yerkes Observatory , and Hans Rosenberg in Göttingen .

The spectrograms showed typical emission lines , u. a. of C 2 and CN in the light of the cometary coma. As for the first time with comet C / 1907 L2 (Daniel) in the previous year, bands in the violet and blue color range were again found in the comet's tail, the cause of which was initially unknown. In 1909, Alfred Fowler was able to identify these spectral lines as emissions of the simply ionized carbon monoxide (CO + ) in a laboratory test . Another strong spectral line in the violet color range was recognized by de La Baume Pluvinel and Baldet as an emission of ionized nitrogen (N 2 + ).

The orbital elements of comet C / 1908 R1, along with those of 18 other extremely long-period comets, were used by Jan Hendrik Oort to derive his hypothesis of the Oort comet cloud .

Orbit

For the comet in 1978 was of 141 observations over a period of 250 days by Marsden a hyperbolic orbit to be determined. More recently, new values ​​for the orbital elements have been calculated from 54 observation data over a period of 88 days (only from the time during the approach to the sun) , but these differ only insignificantly from Marsden's values. The comet's orbit is accordingly inclined by around 140 ° to the ecliptic , so it 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 traversed on December 26, 1908, it was about 141.4 million km from the sun just within the range of the earth's orbit. On October 16, it had already come closest to this with about 1.03 AU / 154.7 million km. On January 24, 1909, the comet then passed Venus at a distance of about 73.0 million km and on February 15, Mars at a distance of about 121.9 million km . On March 27, there was a second approximation to Earth down to about 1.26 AU / 188.8 million km.

For the following information, Marsden's calculations are used, which are based on observations over a longer period of time. After these orbital elements, which are afflicted with a certain degree of uncertainty, the comet moved in an extremely elongated elliptical orbit around the sun before its passage through the inner solar system in 1908 and 1909 . It had an eccentricity of about 0.99984 and a semi-major axis of about 5750 AU, so that its orbit period was about 435,000 years. It may have been a “dynamic new” comet from the Oort cloud, or had only come close to the sun a few times before. During its passage through the inner solar system, the comet saw a number of relatively close passages of the great planets Jupiter , Saturn and Neptune :

Approaches of C / 1908 R1 to Large Planets
date planet Min. Distance (in AU)
February 15, 1896 Jupiter 25.6
August 10, 1898 Neptune 7.9
January 29, 1907 Jupiter 4.1
August 7, 1908 Saturn 8.2
September 22, 1909 Jupiter 3.4
June 27, 1915 Saturn 13.1
November 15, 1918 Jupiter 21.1
June 16, 1920 Neptune 9.8

Its orbital eccentricity was increased to around 1,00038 by their forces of attraction, so that the comet is now departing on a hyperbolic orbit. He will therefore not return to the inner solar system.

See also

Web links

Commons : 1908 R1 (Morehouse)  - collection of pictures, videos and audio files

Individual evidence

  1. ^ W. Sheehan: The Immortal Fire Within: The Life and Work of Edward Emerson Barnard. Cambridge University Press, Cambridge 1995, ISBN 0-521-44489-6 , pp. 359-360.
  2. ^ S. Hughes: Catchers of the Light: The Forgotten Lives of the Men and Women Who First Photographed the Heavens. ArtDeCiel Publishing, 2012, ISBN 978-1-62050-961-6 , p. 442.
  3. ↑ EE Barnard: On the Photographs of Comet c 1908 (Morehouse). In: Monthly Notices of the Royal Astronomical Society. No. LXIX, 1908, pp. 52–54 ( bibcode : 1908MNRAS..69 ... 52B , with pictures of the comet).
  4. ↑ EE Barnard: Comet c 1908 (Morehouse). In: Astrophysical Journal. No. 28, 1908, pp. 292–299 doi: 10.1086 / 141600 ( bibcode : 1908ApJ .... 28..292B , with pictures of the comet).
  5. ^ EE Barnard: Photographic Observations of Comet c 1908 (Morehouse). Second paper. In: Astrophysical Journal. No. 28, 1908, pp. 384–388 doi: 10.1086 / 141607 ( bibcode : 1908ApJ .... 28..384B , with pictures of the comet).
  6. ^ EE Barnard: Photographic Observations of Comet c 1908 (Morehouse). Third paper. In: Astrophysical Journal. No. 29, 1909, pp. 65–71 doi: 10.1086 / 141620 ( bibcode : 1909ApJ .... 29 ... 65B , with pictures of the comet).
  7. ↑ A. Kopff: About the tail development at the comet 1908 c (Morehouse). In: Astronomical News. Vol. 180, No. 8, 1909, pp. 121–124 doi: 10.1002 / asna.19091800802 ( bibcode : 1909AN .... 180..121K ).
  8. ↑ N. Th. Bobrovnikoff: Motion of matter in the tail of Comet 1908 III (Morehouse). In: Lick Observatory Bulletins. No. 398, University of California Press, Berkeley 1928, pp. 161-172 doi: 10.5479 / ADS / bib / 1928LicOB.13.161B ( bibcode : 1928LicOB..13..161B ).
  9. ^ JC Brandt, RD Chapman: Introduction to Comets. Cambridge University Press, Cambridge 2004, ISBN 0-521-80863-4 , p. 24.
  10. ^ AS Eddington: The Envelopes of Comet Morehouse (1908 c). In: Monthly Notices of the Royal Astronomical Society. Vol. LXX, 1910, pp. 442-458 doi: 10.1093 / mnras / 70.5.442 ( bibcode : 1910MNRAS..70..442E ).
  11. ^ SV Orlov: Radial Systems in the Head of the Comet 1908 III (Morehouse). In: Soviet Astronomy. Vol. 1, 1957, pp. 231-234 ( bibcode : 1957SvA ..... 1..231O ).
  12. ^ WW Campbell, S. Albrecht: The Spectrum of Comet c 1908 (Morehouse). In: Astrophysical Journal. Vol. 29, 1909, pp. 84-87 doi: 10.1086 / 141623 ( bibcode : 1909ApJ .... 29 ... 84C ).
  13. ^ J. Hartmann: The spectrum of the comet 1908c (Morehouse). In: Astronomical News. Vol. 181, 1909, p. 21 doi: 10.1002 / asna.19091810204 ( bibcode : 1909AN .... 181 ... 21H ).
  14. ^ A. de La Baume Pluvinel, F. Baldet: Sur le Specter de la Comète 1908 c (Morehouse). In: Bulletin de la Société Astronomique de France et Revue Mensuelle d'Astronomie, de Météorologie et de Physique du Globe. Vol. 22, 1908, pp. 532-534 ( bibcode : 1908BSAFR..22..532B ).
  15. ↑ H. Deslandres, A. Bernard: Recherches spectrales sur la comète Morehouse c 1908. In: Comptes rendus hebdomadaires des séances de l'Académie des sciences. Tome 147 e , Paris 1908, pp. 774-777.
  16. ^ EB Frost, JA Parkhurst: Spectrum of Comet Morehouse (1908c). In: Astrophysical Journal. Vol. 29, 1909, pp. 55-64 ( bibcode : 1909ApJ .... 29 ... 55F , with pictures of the comet).
  17. ^ H. Rosenberg: The Spectrum of Comet 1908 c (Morehouse). In: Astrophysical Journal. Vol. 30, 1909, pp. 267-283 doi: 10.1086 / 141701 ( bibcode : 1909ApJ .... 30..267R ).
  18. ^ D. Leverington: Babylon to Voyager and Beyond: A History of Planetary Astronomy . Cambridge University Press, Cambridge 2003, ISBN 978-0-521-80840-8 , pp. 341-342.
  19. ^ A. Fowler: Investigations relating to the Spectra of Comets. In: Monthly Notices of the Royal Astronomical Society. Vol. LXX, 1910, pp. 484-496 ( bibcode : 1910MNRAS..70..484F ).
  20. ^ A. de La Baume Pluvinel, F. Baldet: Spectrum of Comet Morehouse (1908 c). In: Astrophysical Journal. Vol. 34, 1911, pp. 89-104 doi: 10.1086 / 141873 ( bibcode : 1911ApJ .... 34 ... 89D ).
  21. ^ JH Oort: The Structure of the Cloud of Comets Surrounding the Solar System, and a Hypothesis Concerning Its Origin. In: Bulletin of the Astronomical Institutes of the Netherlands. Vol. 11, No. 408, 1950, pp. 91-110 ( bibcode : 1950BAN .... 11 ... 91O ).
  22. ^ PA Dybczyński: On the famous Oort table. Retrieved November 18, 2015 .
  23. ↑ a b B. G. Marsden, Z. Sekanina, E. Everhart: New Osculating Orbits for 110 Comets and Analysis of Original Orbits for 200 Comets. In: The Astronomical Journal. Vol. 83, no. 1, 1978, pp. 64-71 doi: 10.1086 / 112177 ( bibcode : 1978AJ ..... 83 ... 64M ).
  24. ↑ C / 1908 R1 (Morehouse) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt
  25. ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .