NGC 7088

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In NGC 7088 , also known as Baxendell's Unphotographable Nebula ( dt. "Baxendells unfotografierbarer Fog"), is a well-nonexistent fog about 30 ' north of the globular cluster Messier 2 in Aquarius . After it was "discovered" by the astronomer Joseph Baxendell in Birkdale in 1880 and initially visually confirmed by other astronomers, it was not visible on any photograph . Today it is assumed that the observations were optical illusions and that there is no fog at the corresponding position.

history

On the night of September 28, 1880, Joseph Baxendell observed with his T. Cooke & Sons 6 "telescope in his private observatory in the garden at 14 Liverpool Road, Birkdale a faint, extensive mist in Aquarius, which was new to him and which he never found In his catalog or on a card he owned. In a letter to William Christie dated November 1, 1880, which appeared in the November 12, 1880 edition of the Royal Astronomical Society's Monthly Notices , Baxendell describes the nebula as having an irregular oval shape, the southern limit of which is about 7 ′ north of Messier 2 (M 2) is located and has an extension of 75 '× 52'. Furthermore, Baxendell compares it with the Merope Nebula (NGC 1435), a reflection nebula in the area of ​​the Pleiades (M 45), only that the nebula found is not so bright.

Johan Ludvig Emil Dreyer recorded it in his New General Catalog in 1888 under the number 7088. There he describes it as a very large and diffuse nebula with a length of 45 ′. The nebula was not included in Edward Barnard's catalog of dark clouds in the versions from 1919 and 1927. In the revision of the New General Catalog by Johann Georg Hagen at the Vatican Observatory (1922), it is included in the introduction with 16 other ominous nebulae by Dreyer a density of III – IV on a five-point scale; it is not listed in the catalog itself. Further visual observations of the nebula with different telescopes at different observatories followed until 1930 (→ sightings ).

When relatively sensitive emulsions were available, people began to want to photograph the fog, but no traces of the fog could be found in either the blue or yellow spectral range. Josef Hopmann tried to explain this in a work from 1930 by attributing an extensive, continuous spectrum to the fog.

In 1937, Marcel de Kérolyr from the Observatoire de Haute-Provence was awarded the Klumpke-Roberts Prize for the second time after 1933 for his photographs of the Herschel fields H12, H14, H15, H20, H21, H33, H41 and the Baxendell Nebula NGC 7088 . Two images of NGC 7088 were taken: one on July 18 and the other on September 2, 1934. This was regarded as the first photographic evidence of the nebula. However, Wolfgang Strohmeier and Adalbert Güttler stated in their 1952 publication on NGC 7088 a correspondence from April 4, 1951 with G. Courtés from the Observatoire de Haute-Provence, in which it says that “there is no trace of a fog” on the images gives.

As early as 1927, Max Wolf suspected that the glow of the nebula must be in the red spectral range. Karl Haidrich tried to take photos with an Hα emulsion NGC 7088 in 1936 after the previously used silver bromide emulsions had not produced any results. He also found faint signs of fog, but Haidrich's emulsion at 656 nm was already on the steeply sloping part of the sensitivity curve. In 1947 and 1949, Strohmeier tried to photograph the nebula with an Isopan Ultra emulsion from the Agfa company , whose sensitivity reached up to 680 nm, but did not receive any evidence on any of the photos.

The current state of research assumes that no fog exists at this point. It is assumed that the observations were visual illusions, triggered by reflections from the neighboring Messier 2 in the instrument. The sightings were all done with refractors , the attempted photographs, however, with reflector telescopes .

Sightings

observer time instrument annotation
Baxendell September 28, 1880 6 ″ refractor, Birkdale "I've seen him several nights and no doubt about his existence."
Dreyer between 1881 and 1888 10 ″ refractor, Armagh "I saw it in the Armagh 10" refractor with no difficulty. "
Bigourdan October 27, 1888 12 ″ refractor, Paris "Very slight fog traces in a region 8 ′ more south than assumed by Dreyer."
No sighting on October 5, 1888 and August 2, 1889.
Hagen 1915 and 1917 16 ″ refractor, Vatican
wolf 1927 6 ″ refractor, Heidelberg
O'Connor 1929 15 "refractor, Stonyhurst "Without difficulty"
Franks October 6, 1929 6 "refractor, East Grinstead "On closer inspection, there seems to be a small difference in density between the nebula and the surrounding star zones."
Becker 1930 12 ″ refractor, Potsdam
Lehner 1930 4 ″ refractor, Erfurt

Photographic proof attempts

observer year instrument Emulsion , filter Exposure time Result
Duncan 1919 1.5m mirror, Mount Wilson blue 55 min no evidence
wolf 1927 6 ″ refractor, 16 ″ refractor , 71 cm mirror, Heidelberg blue ? no evidence
Baade 1929 1 m mirror (3 m focal length), Hamburg u. a. panchromatic emulsion + yellow filter 1.5 h -4 h no evidence
de Kérolyr 1931 80 cm mirror, Haute-Provence Opto-Lumière 12 h no evidence
Shapley 1931 40 cm Metcalf Telescope, Harvard Yellow plate + yellow filter 1.5 h no evidence
Helwan 1931 40 cm mirror, Helwan ? 1 h no evidence
de Kérolyr 1934 80 cm mirror, Haute-Provence Lumière-Ortho-Super-Opta 2.5 h no evidence
de Kérolyr 1934 80 cm mirror, Haute-Provence Lumière-Ortho-Super-Fulgur 4.8 h no evidence
Haidrich 1936 21 cm mirror, Vienna Imperial Eclipse Panchromatic 45 min faint signs of blackening
Strohmeier 1947 10 cm Schmidt mirror, Munich Agfa-Isopan-Ultra + red filter RG2 1.5 h no evidence
Strohmeier-Güttler 1949 6.5 cm xenons, Munich Agfa-Isopan-Ultra + red, green, blue filters 6 h no evidence

See also

swell

literature

  • J. Baxendell : A New Nebular . In: Monthly Notices of the Royal Astronomical Society . Vol. 48, 1888, pp. 48 , bibcode : 1880MNRAS..41 ... 48B (English).
  • F. Becker : Cosmic clouds in the vicinity of V and UW Draconis . In: Astronomical News . tape 224 , no. 5359 , 1925, Sp. 113 / 114–117 / 118 , bibcode : 1925AN .... 224..113B .
  • F. Becker: About interstellar masses and the absorption of star light in space . In: Results of the exact natural sciences . tape 9 . Julius Springer, Berlin 1930, p. 1-37 ( Library Archive National Mining University of Ukraine ).
  • G. Bigourdan : Observations de nébuleuses et d'amas stellaires . In: Annales de l'Observatoire de Paris . Observations 1897, 1899, p. G.1 – G.136 , bibcode : 1899AnPOb..46G ... 1. (French).
  • JLE Dreyer : A New General Catalog of Nebulae and Clusters of Stars, being the Catalog of the late Sir John FW Herschel, Bart., Revised, corrected, and enlarged . In: Memoirs of the Royal Astronomical Society . Vol.XLIX, Part I. Royal Astronomical Society, London 1888, pp. 225 (English, archive.org ).
  • JG Hagen : On the significance of Baxendell's nebulosity . In: Monthly Notices of the Royal Astronomical Society . Vol. 90, No. 3, 1930, p. 331–333 , bibcode : 1930MNRAS..90..331H (English).
  • K. Haidrich : The photographic capture of the red fog clouds . In: Astronomical News . tape 258 , no. 6187 , 1936, col. 321 / 322–329 / 330 , bibcode : 1936AN .... 258..321H .
  • A. Latußeck: William Herschel's fifty-two fields of extensive diffused nebulosity - a revision . In: Journal of Astronomical History and Heritage . Vol. 11, No. 3, 2008, p. 235–246 , bibcode : 2008JAHH ... 11..235L (English).
  • R. Pearson: The Brockhurst Observatory . Revised 2014. Astronomy & Space, Nottingham 2014, ISBN 978-1-326-01840-5 , pp. 46-47 (English).
  • W. Steinicke: Baxendell's 'Unphotographable Nebula' . In: Observing and Cataloging Nebulae and Star Clusters . From Herschel to Dreyer's New General Catalog. Cambridge University Press, Cambridge 2010, ISBN 978-0-521-19267-5 , pp. 384-385 (English).
  • W. Strohmeier & A. Güttler : On the question of the existence of the Baxendell nebula NGC 7088 . (Publications of the Munich Observatory, Vol. 4 No. 8). In: Astronomical News . tape 280 , no. 5 , 1952, pp. 254-258 , bibcode : 1952AN .... 280..254S .

Individual evidence

  1. ↑ a b “ A very large and very diffused nebulosity north of the cluster M 2. I have seen it without difficulty in the Armagh 10-inch Refractor. It seems to extend about 35 ′ northwards from the parallel of the [star] 10 ′ [north following] M 2, and to be about 45 ′ in length. ”( Dreyer, 1888 , p. 225)
  2. ^ Entries by Barnard and Hagen cited from Hagen, 1930 , p. 332.
  3. ↑ J. Hopmann : Why can't Hagen's "dark clouds" be photographed? In: Astronomical News . tape 238 , no. 5706 , 1930, col. 285 / 286-293 / 294 , bibcode : 1930AN .... 238..285H .
  4. ^ D. Klumpke Roberts : Presentation of photographs of Sir William Herschel's fields H 12, H 14-15, H 20-21, H 33, H 41 of extensive diffuse nebulosity and of the Baxendell nebulosity NGC 7088 . In: Quarterly magazine of the Astronomical Society . tape 70 , 1935, pp. 330-335 (English).
  5. ↑ «  M. de Kérolyr a bien tenté de photographier la nébuleuse de Baxendell NGC 7088 le 18 July 1934 on 'Super opta' avec 2h30m de pose, et le 2 septembre 1934 sur 'Super fulgur' avec 4h45m de pose. Sur ces deux clichés il n'y a pas la moindre trace de nébuleuse.  »( Strohmeier & Güttler, 1952 , p. 257)
  6. ↑ “ I have, however, seen it on several nights, and have no doubt of its existence. ”( Baxendell, 1881 , p. 48)
  7. ^ "  Traces excessivement faibles de nébulosité que l'on soupçonne en plusieurs endroits dans une région plus australe de 8 ′ que la position de GC  " ( Bigourdan, 1899 , SG83)
  8. ↑ “ On careful attention there does seem to be a slight difference in density between the neb [ula] and surrounding starry zones. ”( Pearson, 2014 , p. 47)

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