Hubble Space Telescope image of NGC 2818 (red: nitrogen, green: hydrogen, blue: oxygen)
Observation data: J2000.0[1] epoch
Right ascension
09h 16m 01.656s[1]
Declination
−36° 37′ 38.76″ [1]
Distance
10,400 ly [2] ly
Apparent dimensions (V)
2' [2]
Constellation
Pyxis
Physical characteristics
Radius
3.25 ly [2] ly
Designations
NGC 2818,[1] PLN 261+8.1[2] ESO 372-PN13
See also: Lists of nebulae
NGC 2818 is a planetary nebula located in the southern constellation Pyxis (The Compass). It consists largely of glowing gases from the star's outer layers ejected during the final stages of its life when it had run out of the fuel necessary to sustain its core fusion processes. The remnants of its core will remain as a white dwarf.
[3]
It is often cited as a member of the open cluster NGC 2818A framing it, however, radial velocity differences between the planetary nebula and open cluster suggest a chance alignment.[4][5] The case is an example of a superimposed pair, similar to NGC 2438 and M46.[5][6]
Partly because of their small total mass, open clusters have relatively poor gravitational cohesion. Consequently, open clusters tend to disperse after a relatively short time, typically some 10 million years, because of external gravitational influences amid other factors. Under exceptional conditions, open clusters can remain intact for up to 100 million years.
Theoretical models predict that planetary nebulae can form from main-sequence stars of between 8 and 1 solar masses, which puts their age at 40 million years and older. Although there are a few hundred known open clusters within that age range, a variety of reasons limit the chances of finding a member of an open cluster in a planetary nebula phase. One such reason is that the planetary nebula phase for more massive stars belonging to younger clusters is on the order of thousands of years - a blink of the eye in cosmic terms. Only one association has been established between open clusters and nearby nebulae, the extremely distant nebula PHR 1315-6555.[5][7]
^ abcdSIMBAD, NGC 2818 (accessed 1 March 2009)
^ abcdScientificBlogging.com, NGC 2818 - A Nebula Within a Cluster Inside A Compass Archived 2013-02-02 at archive.today , staff writer , 2009 January 15th 01:00 AM (accessed 1 March 2009)
^"HubbleSite - NewsCenter - Hubble Snaps a Splendid Planetary Nebula (01/15/2009) - Release Images". hubblesite.org. Retrieved 13 October 2015.
^Mermilliod, J.-C., Clariá, J. J., Andersen, J., Piatti, A. E., Mayor, M. (2001).
Red giants in open clusters. IX. NGC 2324, 2818, 3960 and 6259, A&A
^ abcMajaess D. J., Turner D., Lane D. (2007). In Search of Possible Associations between Planetary Nebulae and Open Clusters, PASP, 119, 1349
^Kiss, L. L., Szabó, Gy. M., Balog, Z., Parker, Q. A., Frew, D. J. (2008). AAOmega radial velocities rule out current membership of the planetary nebula NGC 2438 in the open cluster M46, MNRAS
^"First planetary nebula associated with an open cluster discovered". Deep Sky Observer's Companion – the online database. September 16, 2010. Retrieved 8 November 2014.
NGC2818 is a planetary nebula located in the southern constellation Pyxis (The Compass). It consists largely of glowing gases from the star's outer layers...
is yet another example of a superposed pair, joining the famed case of NGC2818. This is a multi-shell planetary nebula with a bright inner nebula with...
obscuring our galaxy arm there. NGC2818 is a planetary nebula that lies within a dim open cluster of magnitude 8.2. NGC 2818A is an open cluster that lies...
makes for superimposed objects of interest, another instance perhaps being NGC2818. On the other hand, the illuminating star of the bipolar Calabash Nebula...
for a planetary nebula (i.e., a 4% distance solution). The cases of NGC2818 and NGC 2348 in Messier 46, exhibit mismatched velocities between the planetary...
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NGC 257 is a spiral galaxy in the Pisces constellation. It was discovered on December 29, 1790, by Frederick William Herschel. Skrutskie, Michael F.;...
NGC 2800, also known as PGC 26302, is an elliptical galaxy in the constellation Ursa Major. It was discovered February 17, 1831 by William Herschel. Skrutskie...
NGC 2509 is an open cluster in the constellation of Puppis. It was discovered on 3 December 1783 by William Herschel. It was described as "bright, pretty...
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