English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present a detailed analysis of a very high resolution (R\approx 112,000)spectrum of the quasar HE 0515-4414 obtained using the High Accuracy Radialvelocity Planet Searcher (HARPS) mounted on the ESO 3.6 m telescope at the LaSilla observatory. The HARPS spectrum, of very high wavelength calibrationaccuracy (better than 1 m\AA), is used to search for possible systematicinaccuracies in the wavelength calibration of the UV Echelle Spectrograph(UVES) mounted on the ESO Very Large Telescope (VLT). We have carried outcross-correlation analysis between the Th-Ar lamp spectra obtained with HARPSand UVES. The shift between the two spectra has a dispersion around zero of\sigma\simeq 1 m\AA. This is well within the wavelength calibration accuracy ofUVES (i.e \sigma\simeq 4 m\AA). We show that the uncertainties in thewavelength calibration induce an error of about, \Delta\alpha/\alpha\le10^{-6}, in the determination of the variation of the fine-structure constant.Thus, the results of non-evolving \Delta\alpha/\alpha reported in theliterature based on UVES/VLT data should not be heavily influenced by problemsrelated to wavelength calibration uncertainties. Our higher resolution spectrumof the z_{abs}=1.1508 damped Lyman-\alpha system toward HE 0515-4414 revealsmore components compared to the UVES spectrum. Using the Voigt profiledecomposition that simultaneously fits the high resolution HARPS data and thehigher signal-to-noise ratio UVES data, we obtain,\Delta\alpha/\alpha=(0.05\pm0.24)x10^{-5} at z_{abs}=1.1508. This result isconsistent with the earlier measurement for this system using the UVES spectrumalone.Comment: 14 pages, 13 figures, Accepted in A&

Variation of the fine-structure constant: very high resolution spectrum of QSO HE 0515-4414