Stellar laboratories

Abstract

IX. New Se v, Sr ivvii, Te vi, and I vi oscillator strengths and the Se, Sr, Te, and I abundances in the hot white dwarfs G191−B2B and RE 0503−289 ⋆,⋆⋆,⋆⋆⋆ ABSTRACT Context. To analyze spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model-atmosphere techniques are mandatory. Reliable atomic data is crucial for the calculation of such model atmospheres.Aims. We aim to calculate new Sr iv-vii oscillator strengths to identify for the first time Sr spectral lines in hot white dwarf (WD) stars and to determine the photospheric Sr abundances. To measure the abundances of Se, Te, and I in hot WDs, we aim to compute new Se v, Te vi, and I vi oscillator strengths. Methods. To consider radiative and collisional bound-bound transitions of Se v, Sr ivvii, Te vi, and I vi in our NLTE atmosphere models, we calculated oscillator strengths for these ions.Results. We newly identified four Se v, 23 Sr v, 1 Te vi, and three I vi lines in the ultraviolet (UV) spectrum of RE 0503−289. We measured a photospheric Sr abundance of 6.5 +3.8 −2.4 × 10 −4 (mass fraction, 9 500 -23 800 times solar). We determined the abundances of Se (1.6 +0.9 −0.6 × 10 −3 , 8 000 -20 000), Te (2.5 +1.5 −0.9 × 10 −4 , 11 000 -28 000), and I (1.4 +0.8 −0.5 × 10 −5 , 2 700 -6 700). No Se, Sr, Te, and I line was found in the UV spectra of G191−B2B and we could determine only upper abundance limits of approximately 100 times solar. Conclusions. All identified Se v, Sr v, Te vi, and I vi lines in the UV spectrum of RE 0503−289 were simultaneously well reproduced with our newly calculated oscillator strengths.

Quantum mechanical line widths of ionized oxygen, silicon, and aluminium; comparisons with recent experimental results

“…Secondly, the recent discovery of spectral lines emitted by heavy elements (Cu, Zn, Ga, Ge, As, Se, Br, Kr, Sr, Sn, Te, I, etc.) in the ultraviolet (UV) spectra of hot DO white dwarfs such as HD 149499B, PG 0109+111, RE 0503−89 (Werner et al 2018;Rauch et al 2020). These astrophysical objects were known before as composed only in hydrogen and helium.…”

Stark broadening for Br VI and Kr V-VII lines in hot star atmospheres

“…Many recent works (Werner et al 2012;Werner et al 2018a;Werner et al 2018b) have shown the existence of spectral lines emitted by heavy elements in the UV spectra of hot DO white dwarfs. Up to now, 18 trans-iron elements (Z ≥ 30) have been identified in the RE 0503-289 star (Rauch et al 2020), which is a hot DO-type white dwarf. A fur-ther eight trans-iron elements (Zn, Ga, Ge, Se, Sr, Sn, Te, I) were found in PG 0109+111 (Hoyer et al 2018).…”

Sr v–vi line widths in hot white dwarf atmospheres

“…These models should contain opacity of heavy elements. In the meantime, 18 trans-iron elements with atomic numbers in the range 𝑍 = 29 − 56 were detected in the RE 0503−289 hot white dwarf (WD) stars (Rauch et al (2020). Recently, Rauch et al (2017b) detected several heavy elements in hot white dwarfs (Se V, Sr V, Te VI and I VI).…”