The Herschel Space Observatory has uncovered a weird ring of dusty material while obtaining one of the sharpest scans to date of a huge cloud of gas and dust, called NGC 7538. The gigantic ring structure is situated at the center-top of this image. The odd ovoid possesses the mass of 500 suns, with its long axis spanning about 35 light-years and its short axis about 25 light-years.
A weird ring of dusty material seen while Herschel scanned a huge cloud of gas and dust, called NGC 7538. The blue and green colors in this image represent 70- and 160-micron data, respectively, from Herschel's Photoconductor Array Camera and Spectrometer (PACS) instrument. The red colors are 250-micron observations obtained from Herschel's Spectral and Photometric Imaging Receiver (SPIRE) instrument. Image credit: ESA/NASA/JPL-Caltech/Whitman College
Astronomers often see ring and bubble-like structures in cosmic dust clouds. The strong winds cast out by the most massive stars, called O-type stars, can generate these expanding puffs, as can their explosive deaths as supernovas. But no energetic source or remnant of a deceased O-type star, such as a neutron star, is apparent within the center of the ring. It is possible that a big star blew the bubble and, because stars are all in motion, subsequently left the scene, escaping detection.
"Herschel reveals massive cold clumps in NGC 7538." C. Fallscheer, et al. C. Fallscheer et al. 2013 ApJ 773 102 The Astrophysical Journal Volume 773 Number 2. doi:10.1088/0004-637X/773/2/102
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