Orion–Eridanus Superbubble

The Orion–Eridanus Superbubble or Eridanus Soft X-ray Enhancement is a superbubble located west of the Orion Nebula. The region is formed from overlapping supernova remnants that were suspected to be associated with the Orion OB1 stellar association. The bubble is approximately 1200 ly across.^[1] It is the nearest superbubble to the Local Bubble containing the Sun, with the respective shock fronts being about 500 ly apart.^[1]

Soft X-ray image of the Orion-Eridanus Superbubble with ROSAT.

The Orion-Eridanus superbubble in Hydrogen-alpha, with the Barnard's Loop and Eridanus Loop. Image covers the same area of the sky as the left image.

Part of the Orion-Eridanus Superbubble with ROSAT. The contours are 100 Mircon IRAS observations and show the shielding of soft x-rays by a filament.

The Orion–Eridanus Superbubble is formed by the stellar wind of tens of massive stars and 10–20 supernovae.^[2] The superbubble likely formed from the Orion blue stream, which is composed of massive stars in front of the Orion Molecular Cloud Complex. The Orion blue stream begins at around 150 parsec and extends towards Orion OB1 at around 300 parsec. The stream could however include the Bellatrix cluster, which is around 80 parsec distant.^[3]

The structure was discovered from 21 cm radio observations by Carl Heiles and interstellar optical emission line observations by Reynolds and Ogden in the 1970s.^[4]

The Sun might have passed through the Orion–Eridanus Superbubble before it passed through the Local Bubble. This could explain an older peak of iron-60 found in deep sea sediments.^[5]

See also

• Barnard's Loop