Hell N, Miskovicova I, Brown GV, Wilms J, Clementson J, Hanke M, Beiersdorfer P, Liedahl D, Pottschmidt K, Porter FS, Kilbourne CA, Kelley RL, Nowak MA, Schulz NS (2013)
Publication Status: Published
Publication Type: Conference contribution
Publication year: 2013
Publisher: IOP PUBLISHING LTD
Book Volume: T156
Article Number: ARTN 014008
DOI: 10.1088/0031-8949/2013/T156/014008
Strong, relatively short, absorption dips have been observed in the x-ray light curves measured from the high mass x-ray binary system Cygnus X-1. With increasing strength of the dips, which are believed to be caused by 'clumps' of cold material present in the stellar wind of Cyg X-1's companion star, K-shell absorption lines in L-shell ions of Si and S develop. To determine the bulk motion of the clumps via the Doppler shifts of these lines with high accuracy, we measured their reference energies using the Lawrence Livermore National Laboratory electron beam ion trap EBIT-I and EBIT Calorimeter Spectrometer. Our findings-shifts consistent with zero velocity of the absorber throughout all ionization states at orbital phase zero-provide evidence for an onion-like ion structure of the clumps.
APA:
Hell, N., Miskovicova, I., Brown, G.V., Wilms, J., Clementson, J., Hanke, M.,... Schulz, N.S. (2013). Low charge states of Si and S in Cygnus X-1. IOP PUBLISHING LTD.
MLA:
Hell, Natalie, et al. "Low charge states of Si and S in Cygnus X-1." IOP PUBLISHING LTD, 2013.
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