English: This image shows a ROSAT PSPC false-color image of a portion of a nearby stellar wind superbubble stretching across the constellations Eridanus and Orion and known as the Orion-Eridanus Bubble. Soft X-rays are emitted by hot gas (T ~ 2-3 million degrees Celsius) in the interior of this superbubble, and this bright object forms the background for this image of the "shadow" of a filament of gas and dust. The filament is shown by the overlaid contours, which represent 100 micron emission from dust at a temperature of about 30 degrees Kelvin (30 degrees Celsius above absolute zero) as measured by the infrared IRAS satellite. This filament absorbs the soft X-rays in this image (which is made from X-rays of energies between 100 and 300 eV), indicating that the hot gas is located behind the filament. This filament may be part of the shell of neutral gas that surrounds the hot bubble, whose interior is energized by UV light and stellar winds from hot stars in the Orion OB1 association. These stars energize a superbubble about 1200 light years across which is observed in the optical (H alpha) and X-ray portions of the spectrum.