Little Ghost Nebula (NGC 6369)

NGC 6369
NGC 6369: Image taken with the Hubble Space Telescope. © ESA/Hubble & NASA [483]

History

This planetary nebula was discovered by William Herschel on 21 May 1784 using his 20 feet long reflecting telescope with 18.7 inch mirror diameter. He cataloged it as IV 11 and noted: «Pretty bright, round, pretty well defined planetary disk, 30 or 40" diameter.» [464] Herschels son John later cataloged the nebula as h 1981. [466] William Parsons, the 3rd Earl of Rosse, observed the nebula twice in 1851 with his «Leviathan of Parsonstown», the six feet wide reflector and noticed its annular shape and a brighter nordern edge. [486] John L. E. Dreyer added it as NGC 6369 in his famous «New General Catalogue» of 1888 with the description «very remarkable annular planetary, pretty bright, small, round.» [313]

Physical Properties

NGC 6369 is a double-shell planetary nebula. A bright annular inner shell with faint bipolar extensions is surrounded by a filamentary envelope. The inner shell can be described as a barrel-like structure shape with polar bubble-like protrusions. It reveals evidence for H2 and strong polycyclic aromatic hydrocarbons emission from a photodissociative region (PDR) with molecular inclusions located outside the bright inner shell. High-resolution HST narrow-band images reveal a complicated excitation structure of the inner shell and a system of ‘cometary’ knots. The knotty appearance of the envelope, the lack of kinematical evidence for shell expansion and the apparent presence of emission from ionized material outside the PDR suggests that the envelope of NGC 6369 is not a real shell, but a flattened structure at its equatorial regions. Irregular knots and blobs of diffuse emission in low-excitation and molecular line emission have been discovered up to 80 arcsec from the central star. The filaments associated to the polar protrusions have spatial extents consistent with post-shock cooling phases. They likely represent regions of interaction of these structures with surrounding material. [489]

Simbad lists measured distances ranging from 1088 pc to 1139 pc. Magnitudes in different filters are: B 16.6, V 12.0, J 12.452 H 11.873, K 11.475. [145]

«Strasbourg-ESO Catalogue of Galactic Planetary Nebulae» Acker et al., 1992 [141]
DesignationsPN G002.4+05.8: NGC 6369, PK 2+05.1, ARO 51, ESO 520- 03, He 2-232, My 101, Sa 2-207, VV 101, VV' 199, Wray 16- 277
Right Ascension (J2000.0)17h 29m 21s
Declination (J2000.0)-23° 45' 32"
Dimensions 38." (optical)
Distance 2.0 kpc
Radial Velocity-101.0 km/s ± 2.0 km/s
Expansion Velocity 41.6 km/s (O-III)
C-Star DesignationsAG82 243, CD -23 13397, GCRV 10105, HD 158269
C-Star Magnitude16.99 mag (B filter), 15.94 mag (V filter)
C-Star Spectral TypeWC 4
DiscovererHERSCHEL 1784

Finder Chart

The planetary nebula NGC 6369 is located in the constellation obj. The best observation time is in the months March through August.

Chart Little Ghost Nebula (NGC 6369)
Little Ghost Nebula (NGC 6369) in constellation Ophiuchus. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

Visual Observation

400 mm Aperture: In the 21 mm Ethos eyepiece (85x), the planetary nebula is clearly visible as a pale ring with a somewhat darker centre. An O-III filter makes the sky darker while the brightness of the PN remains the same, but does not reveal more details. At slightly higher magnification (16 mm Nagler, 112x) the ring structure is more clearly visible. At even higher magnification, the attraction of the sight fades. — 400 mm f/4.5 Taurus Dobsonian, Glaubenberg, 2. 8. 2022, 21:15, SQM 21.16, Bernd Nies

More Objects Nearby (±15°)

References

141Strasbourg-ESO Catalogue of Galactic Planetary Nebulae; A. Acker, F. Ochsenbein, B. Stenholm, R. Tylenda, J. Marcout, C. Schohn; European Southern Observatory; ISBN 3-923524-41-2 (1992); cdsarc.unistra.fr/viz-bin/cat/V/84 (2021-02-18)
145SIMBAD astronomical database; simbad.u-strasbg.fr/simbad
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
313«A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged» Dreyer, J. L. E. (1888); Memoirs of the Royal Astronomical Society. 49: 1–237; Bibcode:1888MmRAS..49....1D
464«Catalogue of a second thousand of new nebulae and clusters of stars; with a few introductory remarks on the construction of the heavens» William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1789; DOI:10.1098/rstl.1789.0021
466«Observations of nebulæ and clusters of stars, made at Slough, with a twenty-feet reflector, between the years 1825 and 1833» John Frederick William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1833, Pages: 359-505; DOI:10.1098/rstl.1833.0021
483NGC 6369: The Little Ghost Nebula - Astronomy Picture of the Day, 2017 October 28; apod.nasa.gov/apod/ap171028.html (2022-02-04)
486«On the construction of specula of six-feet aperture; and a selection from the observations of nebulæ made with them» William Parsons; Philosophical Transactions of the Royal Society of London, Volume 151, published 1 January 1861; DOI:10.1098/rstl.1861.0029
489«Optical and infrared imaging and spectroscopy of the multiple-shell planetary nebula NGC 6369» G. Ramos-Larios, M. A. Guerrero, R. Vázquez, J. P. Phillips; Monthly Notices of the Royal Astronomical Society, Volume 420, Issue 3, March 2012, Pages 1977–1989; DOI:10.1111/j.1365-2966.2011.20075.x