Limits on the dependence of the fine-structure constant on gravitational potential from white-dwarf spectra

Berengut, J. C. and Flambaum, V. V. and Ong, A. and Webb, J. K. and Barrow, John D. and Barstow, M. A. and Preval, S. P. and Holberg, J. B. (2013) Limits on the dependence of the fine-structure constant on gravitational potential from white-dwarf spectra. Physical Review Letters, 111 (1). ISSN 0031-9007

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Abstract

We propose a new probe of the dependence of the fine-structure constant α on 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 of Δα/α=(4. 2±1.6)×10-5 and (-6.1±5.8)×10-5 from FeV and NiV spectra, respectively, at a dimensionless gravitational potential relative to Earth of Δp≈5×10-5. With better determinations of the laboratory wavelengths of the lines employed these results could be improved by up to 2 orders of magnitude.