Planetary Nebula NGC 6894

Object Description

The planetary nebula NGC 6894 was discovered by William Herschel on July 17, 1784. With an angular diameter of around 40 arc minutes, it appears about as large as Jupiter, but is much fainter: around 14 magnitudes. The distance is about 1669 pc (about 5400 light years). [196]

NGC 6894
NGC 6894: Planetary nebula in Cygnus; 500 mm Cassegrain 5800 mm f/11.4; SBIG STL11K; 50+10+10+10 min LRGB; Bernese Highlands; © 2005 Radek Chromik
NGC 6894
NGC 6894: Planetary nebula in Cygnus; Takahashi Mewlon 250 CR (f=2500 mm / f10), SBIG ST-8300; 17L x 600 sec 1×1, 9R, 11G, 12B 2×2 x 600 sec; Bernese Highlands; © 2016 Bernhard Blank, Dragan Mihajlovic
NGC 6894
NGC 6894: Deep field of NGC 6894 in Hα light with the 1.2m telescope on Mount Hopkins, Arizona in 1992. The inclined lines labeled «b» are galactic latitudes [321]

At first glance, NGC 6894 looks like what appears to be a typical planetary nebula, with a diffuse, spherical outer shell and a tortuous inner structure. The pink color of this nebula could be due to the reddening of the light by intervening clouds of gas and dust in our line of sight. However, this planetary nebula holds a unique surprise, which only becomes apparent on images taken with a particularly long exposure time (deep field): Northwest of the nebula there are faint gas stripes, which are ionized by the central star of NGC 6894 and shine in Hα light. Presumably this gas comes from the halo of the planetary nebula, which hit the interstellar medium. Notably, these streaks of glowing gas are parallel to the galactic plane. It is believed that they aligned along the galactic magnetic field. [321]

«Strasbourg-ESO Catalogue of Galactic Planetary Nebulae» Acker et al., 1992 [141]
DesignationsPN G069.4-02.6: NGC 6894, PK 69-02.1, ARO 110, HE 2- 460, VV 254, VV' 530
Right Ascension (J2000.0)20h 16m 24s
Declination (J2000.0)30° 33' 55"
Dimensions 40." (optical), 55." (radio)
Distance1.5 kpc - 1.9 kpc
Radial Velocity-58.0 km/s ± 6.0 km/s
Expansion Velocity 43.0 km/s (O-III)
C-Star DesignationsAG82 404, CSI +30 -20144 2, GCRV 12649, VES 128
C-Star Magnitude18.1 mag (B filter)
DiscovererHERSCHEL 1823

Finder Chart

The planetary nebula NGC 6894 is located in the constellation Cygnus. The months of April to November are the best observation times.

Chart NGC 6894
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

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)
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
196Celestial Atlas by Curtney Seligman; cseligman.com/text/atlas.htm (2020-12-28)
321«The interaction of the planetary nebula NGC 6894 with the ISM magnetic field» Soker, Noam; Zucker, Daniel B.; Monthly Notices of the Royal Astronomical Society, Volume 289, Issue 3, pp. 665-670.; August 1997; DOI:10.1093/mnras/289.3.665; Bibcode:1997MNRAS.289..665S