Nested shells reveal the rejuvenation of the Orion-Eridanus superbubble
  The Orion-Eridanus superbubble is the prototypical superbubble due to its
proximity and evolutionary state. Here, we provide a synthesis of recent
observational data from WISE and Planck with archival data, allowing to draw a
new and more complete picture on the history and evolution of the
Orion-Eridanus region. We discuss the general morphological structures and
observational characteristics of the superbubble, and derive quantitative
properties of the gas- and dust inside Barnard's Loop. We reveal that Barnard's
Loop is a complete bubble structure which, together with the lambda Ori region
and other smaller-scale bubbles, expands within the Orion-Eridanus superbubble.
We argue that the Orion-Eridanus superbubble is larger and more complex than
previously thought, and that it can be viewed as a series of nested shells,
superimposed along the line of sight. During the lifetime of the superbubble,
HII region champagne flows and thermal evaporation of embedded clouds
continuously mass-load the superbubble interior, while winds or supernovae from
the Orion OB association rejuvenate the superbubble by sweeping up the material
from the interior cavities in an episodic fashion, possibly triggering the
formation of new stars that form shells of their own. The steady supply of
material into the superbubble cavity implies that dust processing from interior
supernova remnants is more efficient than previously thought. The cycle of
mass-loading, interior cleansing, and star formation repeats until the
molecular reservoir is depleted or the clouds have been disrupted. While the
nested shells come and go, the superbubble remains for tens of millions of
years.
