HUBBLE · WFPC2
The Retina Nebula
(IC 4406)
A bipolar planetary nebula seen edge-on, in five narrowband filters.
IC 4406 is a planetary nebula — the shell a dying star throws off once it has run out of fuel. What makes it worth looking at is the angle. The shell is a torus, and we see it edge-on, almost in the plane of its equator, which is why it reads as a rectangle rather than a ring. The Ring Nebula is the same object seen from above.
The dark lanes crossing the interior are what gave it its name. Each is around 160 astronomical units wide, and they show as silhouettes because their dust is a thousand times denser than the rest of the shell — they sit exactly where the hot glowing gas meets the neutral gas that only radio telescopes see. Whether they will survive the nebula's expansion or simply disperse is not known.
Les filaments sombres qui traversent l'intérieur lui ont donné son nom. Chacun mesure environ 160 unités astronomiques de large, et ils apparaissent en silhouette parce que leur poussière est mille fois plus dense que le reste de l'enveloppe — ils se situent exactement là où le gaz chaud rencontre le gaz neutre que seuls les radiotélescopes voient. Survivront-ils à l'expansion de la nébuleuse ou se disperseront-ils : on ne le sait pas.
Processed by Nicolas Rolland, Paris. Data from the NASA/ESA Hubble Space Telescope, obtained from MAST.