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Title: A YOUNG GIANT MOLECULAR CLOUD FORMED AT THE INTERFACE OF TWO COLLIDING SUPERSHELLS: OBSERVATIONS MEET SIMULATIONS

Dense, star-forming gas is believed to form at the stagnation points of large-scale interstellar medium flows, but observational examples of this process in action are rare. We here present a giant molecular cloud (GMC) sandwiched between two colliding Milky Way supershells, which we argue shows strong evidence of having formed from material accumulated at the collision zone. Combining {sup 12}CO, {sup 13}CO, and C{sup 18}O(J = 1-0) data with new high-resolution, three-dimensional hydrodynamical simulations of colliding supershells, we discuss the origin and nature of the GMC (G288.5+1.5), favoring a scenario in which the cloud was partially seeded by pre-existing denser material, but assembled into its current form by the action of the shells. This assembly includes the production of some new molecular gas. The GMC is well interpreted as non-self-gravitating, despite its high mass (M{sub H{sub 2}}∼1.7×10{sup 5} M{sub ⊙}), and is likely pressure confined by the colliding flows, implying that self-gravity was not a necessary ingredient for its formation. Much of the molecular gas is relatively diffuse, and the cloud as a whole shows little evidence of star formation activity, supporting a scenario in which it is young and recently formed. Drip-like formations along its lower edge may bemore » explained by fluid dynamical instabilities in the cooled gas.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [4]
  1. Department of Physics and Astronomy and MQ Research Centre in Astronomy, Astrophysics and Astrophotonics, Macquarie University, NSW 2109 (Australia)
  2. Service d'Astrophysique, CEA/DSM/IRFU Orme des Merisiers, Bat 709 Gif-sur-Yvette F-91191 (France)
  3. Department of Physics and Astrophysics, Nagoya University, Chikusa-ku, Nagoya (Japan)
  4. University Observatory Munich, Scheinerstr. 1, D-81679 München (Germany)
Publication Date:
OSTI Identifier:
22364481
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BUBBLES; CARBON 12; CARBON 13; CARBON 18; CLOUDS; COLLISIONS; GRAVITATION; INTERFACES; INTERSTELLAR SPACE; MASS; MILKY WAY; ORIGIN; RESOLUTION; STAGNATION POINT; STAR EVOLUTION; STARS; THREE-DIMENSIONAL CALCULATIONS