LDN 204: A Cold Spine of Dust Against a Crimson Glow
Stretching like a smoke trail across the summer Milky Way, LDN 204 (Lynds Dark Nebula 204) is a dense filament of cold interstellar dust located about 600 light-years away in the constellation Ophiuchus.
This striking dark nebula absorbs and obscures the light behind it, appearing here as a long, sharply defined shadow cutting across a softly glowing background of faint Hydrogen-alpha emission.
In this LRGB + Ha image, the fine structure of the dust is revealed: delicate wisps and branching tendrils surround a narrow, high-contrast core that runs vertically through the center of the field. The backdrop glows with diffuse red light from excited hydrogen gas in the region, gently lighting the periphery of the cloud like backlit fog.
LDN 204 is part of a larger complex of dark nebulae associated with the Sh2-27 H II region, surrounding the bright star Ophiuchi a runaway O-type star whose radiation and stellar winds are shaping the surrounding gas and dust, likely influencing the structure seen here.
Though starless to the eye, this dark river is rich with molecular gas, potentially harboring early-stage cores where future stars may one day form. The dark lanes seen here are among the coldest and densest objects in the interstellar medium—visible only because they block the light behind them.
Imaged in LRGB and H alpha on my Planewave DR 350 at Observatorio El Sauce, Chile.
Image Acquisition and Processing: Mike Selby