J. C. Berengut, V. V. Flambaum, A. Ong, J. K. Webb, John D. Barrow, M. A. Barstow, S. P. Preval, J. B. Holberg
We propose a new probe of the variation of the fine structure constant, alpha, in a strong gravitational field using metal lines in the spectra of white dwarf stars. Comparison of laboratory spectra with far-UV astronomical spectra from the white dwarf star G191-B2B recorded by the Hubble Space Telescope Imaging Spectrograph gives limits on the fractional variation of alpha of (Delta alpha/alpha)=(4.2 +- 1.6)x10^(-5) and (-6.1 +- 5.8)x10^(-5) from Fe V and Ni V spectra, respectively, at a dimensionless gravitational potential relative to Earth of (Delta phi) ~ 5x10^(-5). With better determinations of the laboratory wavelengths of the lines employed these results could be improved by up to two orders of magnitude.
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http://arxiv.org/abs/1305.1337
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