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An infrared ring around the magnetar SGR 1900+14


Magnetars1,2 are a special class of slowly rotating (period 5–12 s) neutron stars with extremely strong magnetic fields (>1014G)—at least an order of magnitude larger than those of the ‘normal’ radio pulsars. The potential evolutionary links and differences between these two types of object are still unknown; recent studies, however, have provided circumstantial evidence connecting magnetars with very massive progenitor stars3,4,5. Here we report the discovery of an infrared elliptical ring or shell surrounding the magnetar SGR 1900+14. The appearance and energetics of the ring are difficult to interpret within the framework of the progenitor’s stellar mass loss or the subsequent evolution of the supernova remnant. We suggest instead that a dust-free cavity was produced in the magnetar environment by the giant flare emitted by the source in August 1998. Considering the total energy released in the flare, the theoretical dust-destruction radius matches well with the observed dimensions of the ring. We conclude that SGR 1900+14 is unambiguously associated with a cluster of massive stars, thereby solidifying the link between magnetars and massive stars.

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Figure 1: The infrared ring around SGR 1900+14.


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This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory (JPL), California Institute of Technology (Caltech), under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This publication also makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/Caltech, funded by NASA and the NSF. J.G. gratefully acknowledges a Royal Society Wolfson Research Merit Award. V.V.D. acknowledges support from the NSF and discussions with R. McCray, A. Crotts and R. Chevalier. D.F. acknowledges support from NASA through the Long Term Space Astrophysics programme, and by the New York State Foundation for Science, Technology, and Innovation Faculty Development Program grant.

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Correspondence to S. Wachter.

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Supplementary Data

The file contains Supplementary Data which includes additional details regarding the light echo scenario, the dust heating considerations, and the flare energetics and anisotropy. (PDF 95 kb)

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Wachter, S., Ramirez-Ruiz, E., Dwarkadas, V. et al. An infrared ring around the magnetar SGR 1900+14. Nature 453, 626–628 (2008).

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