A ghostly bubble adrift in space — IC 5148.
About 3,000 light years away in the constellation Grus, this planetary nebula formed when a Sun-like star exhausted its fuel and shed its outer layers, leaving behind an intensely hot white dwarf that now illuminates the expanding gas. Spanning about 2 light years across and appearing roughly 2 arcminutes wide on the sky, IC 5148 is often nicknamed the “Spare Tyre Nebula.” However that name mainly reflects what short exposures show — just the bright inner ring. This deep image goes far beyond that, revealing the vast, delicate halo of gas flowing outward and the complex structures surrounding the core.
Look closely and you’ll see multiple faint outer shells from successive pulses of mass loss, subtle asymmetries shaped by the surrounding interstellar medium, and even fine radial filaments tracing ionization fronts racing through space. The nebula’s central star is blisteringly hot — about 110,000 K — making IC 5148 a textbook example of a high-excitation planetary nebula. That’s why the teal [O III] light dominates so strongly over Hα (red): oxygen atoms are stripped of two electrons and radiate powerfully as they recombine, especially in the rarefied outer halo where hydrogen emission is faint.
A dying star’s final breaths, written in light and drifting into the darkness.
Imaged in Ha OIII and RGB on my Planewave CDK 1000 at Observatorio El Sauce, Chile.
Image acquisition and processing: Mike Selby