Iranian, English Researchers Provide a 3D Map of the Hot Local Bubble

Tuesday, July 9, 2019 - 12:57

Researchers of Iran Institute for Research in Fundamental Sciences and Keele University have provided a three-dimensional map of the hot Local Bubble by using diffuse interstellar bands.

According to the research, published in Nature Astronomy and carried out by Amin Farhang, Jacco Th. van Loon, Habib G. Khosroshahi, Atefeh Javadi and Mandy Bailey, the Solar System is located within a low-density cavity known as the Local Bubble, which appears to be filled with an X-ray-emitting gas at a temperature of 106 K (ref.).

Such conditions are too harsh for typical interstellar atoms and molecules to survive. The diffuse interstellar bands (DIBs), the carriers of which remain largely unidentified, often appear as absorption features in stellar spectra and can be used to trace interstellar gas.

Here researchers report the three-dimensional (3D) structure of the Local Bubble using two different DIB tracers (λ5,780 and λ5,797), which reveals that DIB carriers are present within the Bubble. The 3D map shows low values of λ5,797/λ5,780 inside the Bubble compared with the outside.

This finding proves that the carrier of the λ5,780 DIB can withstand X-ray photo dissociation and sputtering by fast ions, whereas the carrier of the λ5,797 DIB succumbs. This implies that DIB carriers are more stable than hitherto thought, and that the carrier of the λ5,780 DIB must be larger than that of the λ5,797 DIB.

Alternatively, small-scale denser (and cooler) structures that shield some of the DIB carriers must be prevalent within the Bubble, suggesting that such structures may be an intrinsic feature of supernova-driven bubbles.

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