Show simple item record

dc.contributor.authorVennes, Stéphane
dc.contributor.authorKawka, Adéla
dc.contributor.authorNémeth, Péter
dc.date.accessioned2014-10-05T21:39:20Z
dc.date.available2014-10-05T21:39:20Z
dc.date.issued2011-06-01
dc.identifier.citationVennes, S., Kawka, A., & Németh, P. (2011). Pressure shifts and abundance gradients in the atmosphere of the DAZ white dwarf GALEX J193156.8+011745. Monthly Notices of the Royal Astronomical Society, 413(4), 2545-2553.en_US
dc.identifier.urihttp://hdl.handle.net/11141/329
dc.description.abstractWe present a detailed model atmosphere analysis of high-dispersion and high signal-to-noise ratio spectra of the heavily polluted DAZ white dwarf GALEX J1931+0117. The spectra obtained with the Very Large Telescope (VLT)-Kueyen/UV-Visual Echelle Spectrograph show several well-resolved Siii spectral lines enabling a study of pressure effects on line profiles. We observed large Stark shifts in silicon lines in agreement with theoretical predictions and laboratory measurements. Taking into account Stark shifts in the calculation of synthetic spectra, we reduced the scatter in individual line radial velocity measurements from ∼3 to ≲1kms-1. We present revised abundances of O, Mg, Si, Ca and Fe based on a critical review of line-broadening parameters and oscillator strengths. The new measurements are generally in agreement with our previous analysis with the exception of magnesium with a revised abundance of a factor of 2 lower than previously estimated. The magnesium, silicon and iron abundances exceed solar abundances, but the oxygen and calcium abundances are below solar. Also, we compared the observed line profiles to synthetic spectra computed with variable accretion rates and vertical abundance distributions assuming diffusive steady state. The inferred accretion rates vary from for calcium to 2 × 109gs-1 for oxygen. We find that the accretion flow must be oxygen rich while being deficient in calcium relative to solar abundances. The lack of radial velocity variations between two measurement epochs suggests that GALEX J1931+0117 is probably not in a close binary and that the source of the accreted material resides in a debris disc.en_US
dc.language.isoenen_US
dc.rightsThis article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2011 The authors. Published by Oxford University Press. All rights reserved.en_US
dc.rights.urihttp://www.oxfordjournals.org/en/access-purchase/rights-and-permissions/self-archiving-policyp.htmlen_US
dc.titlePressure shifts and abundance gradients in the atmosphere of the DAZ white dwarf GALEX J193156.8+011745en_US
dc.typeArticleen_US
dc.identifier.doi10.1111/j.1365-2966.2011.18323.x


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record