A 100 pc elliptical and twisted ring of cold and dense molecular clouds revealed by Herschel around the galactic center

Molinari, S., Bally, J., Noriega-Crespo, A., Compiegne, M., Bernard, J.P., Paradis, D., Martin, P., Testi, L., Barlow, M., Moore, T., Plume, R., Swinyard, B., Zavagno, A., Calzoletti, L., M. Di Giorgio, A., Elia, D., Faustini, F., Natoli, P., Pestalozzi, Michele, Pezzuto, S., Piacentini, F., Polenta, G., Polychroni, D., Schisano, E., Traficante, A., Veneziani, M., Battersby, C., Burton, M., Carey, S., Fukui, Y., Li, J.Z., Lord, S.D., Morgan, L., Motte, F., Schuller, F., Stringfellow, G.S., Tan, J.C., Thompson, Mark, Ward-Thompson, D., White, G. and Umana, G. (2011) A 100 pc elliptical and twisted ring of cold and dense molecular clouds revealed by Herschel around the galactic center. Astrophysical Journal Letters, 735 (2): L33. ISSN 2041-8213

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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 × 107 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.

Item Type	Article
Identification Number	10.1088/2041-8205/735/2/L33
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Keywords	galaxy : center, ism : clouds, stars : formation
Date Deposited	15 May 2025 12:11
Last Modified	10 Feb 2026 06:42