Diffuse x-ray emission from the quiescent superbubble M17, the omega nebula

Bryan C. Dunne, You Hua Chu, C. H. Rosie Chen, Justin D. Lowry, Leisa Townsley, Robert A. Gruendl, Martín A. Guerrero, Margarita Rosado

Research output: Contribution to journalArticlepeer-review


The emission nebula M17 contains a young ∼1 Myr old open cluster; the winds from the OB stars of this cluster have blown a superbubble around the cluster. ROSAT observations of M17 detected diffuse X-ray emission peaking at the cluster and filling the superbubble interior. The young age of the cluster suggests that no supernovae have yet occurred in M17; therefore, it provides a rare opportunity to study hot gas energized solely by shocked stellar winds in a quiescent superbubble. We have analyzed the diffuse X-ray emission from M17 and compared the observed X-ray luminosity of ∼2.5 × 1033 ergs s-1 and the hot gas temperature of ∼8.5 × 10 6 K and mass of ∼1 M⊙ to model predictions. We find that bubble models with heat conduction overpredict the X-ray luminosity by 2 orders of magnitude; the strong magnetic fields in M17, as measured from H I Zeeman observations, have most likely inhibited heat conduction and associated mass evaporation. Bubble models without heat conduction can explain the X-ray properties of M17, but only if cold nebular gas can be dynamically mixed into the hot bubble interior and the stellar winds are clumpy with mass-loss rates reduced by a factor of ≥3. Future models of the M17 superbubble must take into account the large-scale density gradient, small-scale dumpiness, and strong magnetic field in the ambient interstellar medium.

Original languageEnglish (US)
Pages (from-to)306-313
Number of pages8
JournalAstrophysical Journal
Issue number1 I
StatePublished - Jun 10 2003


  • H II regions
  • ISM: bubbles
  • ISM: individual (M17)
  • Stars: early-type
  • Stars: winds, outflows

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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