M57

Object: M57 Camera: Meade DSI Pro II
Date: 5/19/2009 Telescope: Meade 80mm ED refractor
Total Exposure: LRGB - 87':30':30':30' Subexposures: 3 minutes each
Mount: Orion Sirius EQ-G Guiding: PHD - Orion StarShoot Auto Guider
Location: West Boylston, MA Guide Scope: Orion Short Tube 80
Processing:
  • Nebulosity Processing:
    1. Dark frame calibration
    2. Each color channel Aligned and Combined
    3. Each of those sets aligned with each other
  • Photoshop:
    1. Each channel imported using Fits Liberator plug-in
    2. Curves and Levels adjusted to each channel
    3. Red, Green and Blue channels RGB merged
    4. Luminance data added via Steve Cannistra's Luminance Corrected LRGB method
    5. More curves and levels adjustments to taste
    6. Ran NoeL Carbonni's "reduce small blue halo's" action
    7. Reduced background noise
    8. Adjusted background sky values for better balance
    9. Removed remaining gradient
 Description:
M57
AKA "The Ring Nebula"

Discovered by Antoine Darquier de Pellepoix in 1779.
The famous ring nebula M57 is often regarded as the prototype of a planetary nebula, and a showpiece in the northern hemisphere summer sky. Recent research has confirmed that it is, most probably, actually a ring (torus) of bright light-emitting material surrounding its central star, and not a spherical (or ellipsoidal) shell, thus coinciding with an early assumption by John Herschel. Viewed from this equatorial plane, it would thus more resemble the Dumbbell Nebula M27 or the Little Dumbbell Nebula M76 than its appearance we know from here: We happen to view it from near one pole.
This is contrary to the belief expressed e.g. in Kenneth Glyn Jones' book. There are even indications from investigations of deep observations such as George Jacoby's deep photos obtained at Kitt Peak National Observatory that the overall shape might be more that of a cylinder viewed along the direction of the axis than that of a ring, i.e., we are looking down a tunnel of gas ejected by a star at the end of its nuclear-burning life. Eventually, these observations have given evidence that the equatorial ring or cylinder has lobe-shaped extensions in polar directions, similar to those found in deep images of M76, but even more resembling other planetaries like NGC 6302, see e.g. the review by Sun Kwok (2000).