The VLT-FLAMES Tarantula Survey. IX. (van Loon et al.)

Vol. 550
In section 6. Interstellar and circumstellar matter

The VLT-FLAMES Tarantula Survey. IX. The interstellar medium seen through diffuse interstellar bands and neutral sodium

The Tarantula Nebula (or 30 Doradus), a bright star-forming region in the Large Magellanic Cloud (LMC), has been mapped to observe in absorption the diffuse interstellar bands (DIBs), derive hints to their carriers, and probe the diffuse, cool-warm gas in front of it. They observed over 800 early-type stars with the VLT-Flames instrument in the Tarantula, and derived DIB absorption maps for the Galactic and LMC gas, including a smaller region near the central cluster R136. The DIB lines were compared to the neutral sodium (Na) lines. Both in the LMC and the solar neighborhood, the 4428,5780-97 and 6614 A DIBs features are correlated with Na absorption and visual extinction, and they are destroyed in irradiated and harsh environments. Only the 4428 feature is already present at low Na density, and is more robust. Its carrier must be large, compact, and neutral. Stellar winds from the central cluster R136 have created an expanding shell. Some infalling gas is also detected and is reminiscent of a galactic "fountain".