Turtle Nebula (NGC 6210)

NGC 6210
NGC 6210: Image taken with the Hubble Space Telescope. © ESA/Hubble & NASA, Judy Schmidt [165]

History

This planetary nebula was first recorded on 22 March 1799 by the French astronomer Jérôme Lalande. He measured its position very accurately for his star catalogue «Histoire céleste française» which appeared in 1801. But Lalande did not recognize the true nature of what he thought was a star and hence Dreyer credited Wilhelm Struve for its discovery. Struve found the object in 1825 while he was searching for double stars with the 9.6 inch f/17.8 Fraunhofer refractor at Dorpat (Tartu) in Estland. He found 13 NGC objects which he published in 1827. [196]

John Herschel observed this planetary nebula on 25 May 1830. He cataloged it as h 1970 and noted: «Struve's fifth nebula in the list at the end of the Dorpat Catalogue of double stars. Very bright equal to a star 8 or 8.9 magnitude. 8" diameter, and of a uniform light, but with the edges boiling and ragged. A fine object like a star out of focus. Viewed between clouds. Struve's place.» [466]

Physical Properties

The dying central star of the planetary nebula NGC 6210 is surrounded by a complicated structure, which looks like a «nautilus shell». The remarkable features of this nebula are the numerous holes in the inner shells with jets of material streaming from them. These jets produce column-shaped features that are mirrored in the opposite direction. The multiple shells of material ejected by the dying star give this planetary nebula its odd form. The fainter outer structure resembles a «tortoise» (sea turtle). This is how the PN got its nickname «Turtle Nebula».

Material flung off by this central star is streaming out of holes it punched in the nautilus shell. At least four jets of material can be seen: a pair near 6 and 12 o'clock and another near 2 and 8 o'clock. In each pair, the jets are directly opposite each other, exemplifying their bipolar nature. The jets are thought to be driven by a fast wind – material propelled by radiation from the hot central star. In the inner shell, bright rims outline the escape holes created by this wind. This same wind appears to give rise to the prominent outer jet in the same direction. The hole in the inner shell acts like a hose nozzle, directing the flow of material.

NGC 6210 is about 6,600 light-years away. The nebula measures 1.6 light-years from the very top of the turtle-shaped form to the tip of the bottom. The inner nautilus shell is about 0.5 light-years in diameter. [482]

«Strasbourg-ESO Catalogue of Galactic Planetary Nebulae» Acker et al., 1992 [141]
DesignationsPN G043.1+37.7: NGC 6210, PK 43+37.1, ARO 5, EM* CDS 904;VV 82, VV' 143
Right Ascension (J2000.0)16h 44m 29s
Declination (J2000.0)+23° 47' 48"
Dimensions 16.2" (optical)
Radial Velocity-36.2 km/s ± 1.1 km/s
Expansion Velocity 21.0 km/s (O-III), 35.5 km/s (N-II)
C-Star DesignationsAG +23 1564, AG82 216, BD +24 3048A, GCRV 9624, HD 151121, IDS 16403+23.59A, PLX 3808
C-Star Magnitude12.44 mag (B filter), 12.66 mag (V filter)
C-Star Spectral TypeO6, O(H)
DiscovererSTRUVE 1827

Finder Chart

The planetary nebula NGC 6210 is located in the constellation Hercules. The best observation time is from March to October.

Chart Turtle Nebula (NGC 6210)
Turtle Nebula (NGC 6210) in constellation Hercules. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

More Objects Nearby (±25°)

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
165Flickr: Judy Schmidt; flickr.com/people/geckzilla (2021-01-02)
196Celestial Atlas by Curtney Seligman; cseligman.com/text/atlas.htm (2020-12-28)
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
482A Turtle-Shaped Nebula, NGC 6210, and the Structure around its Star; hubblesite.org/contents/media/images/1998/36/720-Image.html (2022-02-03)