A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455-282, WD0621-376, and WD2211-495

Abstract

Using newly obtained high-resolution data ($R\sim 1\times {10}^5$) from the \textit{Hubble Space Telescope}, and archival UV data from the \textit{Far Ultraviolet Spectroscopic Explorer} we have conducted a detailed UV survey of the three hot, metal-polluted white dwarfs WD0455-282, WD0621-376, and WD2211-495. Using bespoke model atmospheres we measured $T_{\mathrm{eff}}$, log $g$, and photospheric abundances for these stars. In conjunction with data from Gaia we measured masses, radii, and gravitational redshift velocities for our sample of objects. We compared the measured photospheric abundances with those predicted by radiative levitation theory, and found that the observed Si abundances in all three white dwarfs, and the observed Fe abundances in WD0621-376 and WD2211-495, were larger than those predicted by an order of magnitude. These findings imply not only an external origin for the metals, but also ongoing accretion, as the metals not supported by radiative levitation would sink on extremely short timescales. We measured the radial velocities of several absorption features along the line of sight to the three objects in our sample, allowing us to determine the velocities of the photospheric and interstellar components along the line of sight for each star. Interestingly, we made detections of circumstellar absorption along the line of sight to WD0455-282 with three velocity components. To our knowledge, this is the first such detection of multi-component circumstellar absorption along the line of sight to a white dwarf.

arXiv comment19 pages, 23 figures, 8 tables. Accepted for publication in the Monthly Notices of the Royal Astronomical Society

References in corpus (30)

• Overview of the Far Ultraviolet Spectroscopic Explorer Mission
• A disintegrating minor planet transiting a white dwarf
• An Improved Spectroscopic Analysis of DA White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• The frequency of planetary debris around young white dwarfs
• Spectroscopic Analysis of DA White Dwarfs: Stark Broadening of Hydrogen Lines Including Non-Ideal Effects
• A gaseous metal disk around a white dwarf
• The Structure of the Local Interstellar Medium V: Electron Densities
• A Comprehensive Spectroscopic Analysis of DB White Dwarfs
• Non-linear Least Squares Fitting in IDL with MPFIT
• Evidence for a systematic offset of -80 micro-arcseconds in the Gaia DR2 parallaxes
• 3D maps of the local ISM from inversion of individual color excess measurements
• Found: The missing blue opacity in atmosphere models of cool hydrogen white dwarfs
• A planetesimal orbiting within the debris disc around a white dwarf star
• Elemental Compositions of Two Extrasolar Rocky Planetesimals
• An aluminum/calcium-rich, iron-poor, white dwarf star: evidence for an extrasolar planetary lithosphere?
• Drifting Asteroid Fragments Around WD 1145+017
• High-speed photometry of the disintegrating planetesimals at WD1145+017: evidence for rapid dynamical evolution
• Evidence for an external origin of heavy elements in hot DA white dwarfs
• Heavy element abundance patterns in hot DA white dwarfs
• Carbon to oxygen ratios in extrasolar planetesimals
• Multiwavelength Transit Observations of the Candidate Disintegrating Planetesimals Orbiting WD 1145+017
• Circumstellar features in hot DA white dwarfs
• Evidence for Gas from a Disintegrating Extrasolar Asteroid
• The white dwarf mass-radius relation and its dependence on the hydrogen envelope
• The Gaia spectrophotometric standard stars survey - III. Short-term variability monitoring
• Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT19868
• A comprehensive near and far ultraviolet spectroscopic study of the hot DA white dwarf G191-B2B
• The distribution of metals in hot DA white dwarfs
• Constraining the magnetic field on white dwarf surfaces; Zeeman effects and fine structure constant variation
• Hot DA white dwarf model atmosphere calculations: Including improved Ni PI cross sections

Cited by in corpus (4)

• The spectral evolution of white dwarfs: where do we stand?
• Evidence for post-nebula volatilisation in an exo-planetary body
• The bright blue side of the night sky: Spectroscopic survey of bright and hot (pre-) white dwarfs
• Non-local thermodynamic equilibrium spectral analysis of five hot, hydrogen-deficient pre-white dwarfs