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Published July 10, 2011 | Published + Submitted
Journal Article Open

A 100 pc Elliptical and Twisted Ring of Cold and Dense Molecular Clouds Revealed by Herschel Around the Galactic Center

Abstract

Thermal images of cold dust in the Central Molecular Zone of the Milky Way, obtained with the far-infrared cameras on board the Herschel satellite, reveal a ~3 × 10^7 M_☉ ring of dense and cold clouds orbiting the Galactic center. Using a simple toy model, an elliptical shape having semi-major axes of 100 and 60 pc is deduced. The major axis of this 100 pc ring is inclined by about 40° with respect to the plane of the sky and is oriented perpendicular to the major axes of the Galactic Bar. The 100 pc ring appears to trace the system of stable x_2 orbits predicted for the barred Galactic potential. Sgr A⋆ is displaced with respect to the geometrical center of symmetry of the ring. The ring is twisted and its morphology suggests a flattening ratio of 2 for the Galactic potential, which is in good agreement with the bulge flattening ratio derived from the 2MASS data.

Additional Information

© 2011 The American Astronomical Society. Received 2011 February 14; accepted 2011 May 17; published 2011 June 21. Data processing and map production have been possible thanks to ASI support via contract I/038/080/0. We thank the referee M.Morris for useful comments that led to a more focused paper. We thank L. Spinoglio, N. Sacchi, and A. Marconi for useful discussions on AGNs. We also thank M. Pohlen and the SPIRE ICC for the preliminary analysis on the SPIRE "brightsource mode" calibration.

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Published - Molinari2011p15502Astrophys_J_Lett.pdf

Submitted - 1105.5486.pdf

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August 22, 2023
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