Messier 57 (M57) planetary nebula, also known as the "Ring Nebula", is often regarded as the prototype of a planetary nebula. Observations have 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.

This image was obtained and processed by members of the IAC astrophotography group (A. Oscoz, D. López, P. Rodríguez-Gil and L. Chinarro).

Credit: Daniel López (IAC).

Date: 2009.

Technical information:
Telescope: 2.5-m Isaac Newton Telescope.
Instrument: Wide Field Camera.
Detector: EEV.
Filters and exposure times: It is a three-colour composite made from data collected using filters to isolate the light emitted by hydrogen alpha (H-alpha), doubly ionised oxygen (OIII) and ionised sulfur (SII) atoms, and coded in the image as red, green and blue respectively.

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