NGC 7293

Planetary Nebula NGC 7293 (= Bennett 129) in Aquarius

The Helix Nebula

Right Ascension 22 : 29.6 (h:m)

Declination -20 : 48 (deg:m)

Distance 0.45 (kly)

Visual Brightness 7.3 (mag)

Apparent Dimension 16 / 28 (arc min)

Right Ascension	22 : 29.6 (h:m)
Declination	-20 : 48 (deg:m)
Distance	0.45 (kly)
Visual Brightness	7.3 (mag)
Apparent Dimension	16 / 28 (arc min)

Discovered by Karl Ludwig Harding before 1824.

Overlooked by previous astronomers, notably F.W. Herschel, this nebula was discovered by Karl Ludwig Harding in the course of his sky surveys before 1824 (Harding 1824).

The Helix Nebula is one of the closest of all planetary nebulae: Lying at a distance of perhaps 450 light years, it is the only planetary nebula for which a parallax could be obtained by ground-based observations. Nevertheless, its distance is quite uncertain: The first determination by A. Van Maanen yielded about 85 light-years, Becvar (1961) has 590, L. Kohoutek (1962) 280, I.S. Shlovskii (1956) and P.A. Ianna & H.A. McAlister (1974) 160, the Sky Catalogue 2000.0 gives about 300 ly, and C.R. O'Dell (1963) obtains 450 light-years.

It is also one of the apparently largest planetaries known: Its apparent size covers an area of 16 arc minutes diameter, more than half of that of the full moon; it halo extends even further to 28 arc minutes or almost the moon's apparent diameter (These dimensions were taken from Stephen J. Hynes who quotes AAT and ESO photos). Although the nebula is quite bright, its light is spread over this large area so that it is not an easy object for visual observing; the Herschels have apparently never cataloged or observed it.

The popular name Helix Nebula refers to the nebula's appearance on photographs.

Our image was obtained by David Malin with the Anglo-Australian Telescope. This image is copyrighted by the Australian Astronomical Observatory; see their usage policy.

More information on thie image (David Malin)

In the SAC 110 best NGC object list. In the RASC's Finest N.G.C. Objects Objects list. In John Caldwell's list. Caldwell 63.

Bill Arnett's Helix Nebula NGC 7293 page (former The Web Nebula page).

Hubble Space Telescope images of the Helix Nebula NGC 7293:

Details in the Helix Nebula (STScI PR 1996-13)
Full Mosiac with the new ASC (STScI PR 2003-11)

SIMBAD Data of NGC 7293

Publications on NGC 7293 (NASA ADS)

Observing Reports for NGC 7293 (IAAC Netastrocatalog)

NGC Online data for NGC 7293

References

Karl Ludwig Harding, 1824. Astronomische Nachrichten,Beobachtungen des diesjährigen Kometen, dessen Doppelschweif etc., neue Nebelflecke, und über den Anblick des gestirnten Himmels in Egypten, aus einem Schreiben des Hrn. Dr. Westphal, mitgetheilt vom Hrn. Prof. und Astronomen Harding in Göttingen, unterm 28. April c. Astronomisches Jahrbuch für das Jahr 1827, pp. 131-135. Here p. 134.

Hartmut Frommert
Christine Kronberg
[contact]

Last Modification: June 9, 2008