First detection of bromine and antimony in hot stars

Werner, K.; Rauch, T.; Knoerzer, M.; Kruk, J. W.

doi:10.1051/0004-6361/201832723

Cited by 20 publications

(19 citation statements)

References 27 publications

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“…Several lines in the IUE spectrum return a non-detection compatible with this upper limit, for example Mo v λλ 1586.898, 1774.317 Å. As for HD 127493 Mo v λλ 1586.898, 1590.414, 1653.541 1661.215 1774.317 Å exclude abundances higher than log Mo/H ≤ −6.1 ± 0.4 (2200 times solar) Werner et al (2018). have recently measured photospheric abundances of antimony in two DO white dwarfs: RE 0503−289 and PG 0109+111.…”

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confidence: 72%

Heavy metals in intermediate He-rich hot subdwarfs: the chemical composition of HZ 44 and HD 127493

Dorsch¹,

Latour

Heber³

2019

A&A

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Context. Hot subluminous stars can be spectroscopically classified as subdwarf B (sdB) and O (sdO) stars. While the latter are predominantly hydrogen deficient, the former are mostly helium deficient. The atmospheres of most sdOs are almost devoid of hydrogen, whereas a small group of hot subdwarf stars of mixed H/He composition exists, showing extreme metal abundance anomalies. Whether such intermediate helium-rich (iHe) subdwarf stars provide an evolutionary link between the dominant classes is an open question.Aims. The presence of strong Ge, Sn, and Pb lines in the UV spectrum of HZ 44 suggests a strong enrichment of heavy elements in this iHe-sdO star and calls for a detailed quantitative spectral analysis focusing on trans-iron elements. Methods. Non-LTE model atmospheres and synthetic spectra calculated with TLUSTY/SYNSPEC are combined with high-quality optical, UV and FUV spectra of HZ 44 and its hotter sibling HD 127493 to determine their atmospheric parameters and metal abundance patterns.Results. By collecting atomic data from literature we succeeded to determine abundances of 29 metals in HZ 44, including the transiron elements Ga, Ge, As, Se, Zr, Sn, and Pb and provide upper limits for 10 other metals. This makes it the best described hot subdwarf in terms of chemical composition. For HD 127493 the abundance of 15 metals, including Ga, Ge, and Pb and upper limits for another 16 metals were derived. Heavy elements turn out to be overabundant by one to four orders of magnitude with respect to the Sun. Zr and Pb are among the most enriched elements.Conclusions. The C, N, and O abundance for both stars can be explained by nucleosynthesis of hydrogen burning in the CNO cycle along with their helium enrichment. On the other hand, the heavy-element anomalies are unlikely to be caused by nucleosynthesis. Instead diffusion processes are evoked with radiative levitation overcoming gravitational settlement of the heavy elements.

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confidence: 72%

Heavy metals in intermediate He-rich hot subdwarfs: the chemical composition of HZ 44 and HD 127493

Dorsch¹,

Latour

Heber³

2019

A&A

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“…For example, new Ar VI [1] and Ar VII [2] lines have been discovered in hot stars and white dwarfs. Werner et al [3] detected Br VI, Sb V and Sb VI ions for the first time in heliumrich white dwarfs. The analysis of the spectra needs atomic and line broadening data: for the evaluation of the abundance of Ba V, Ba VI, and Ba VII [4] and of the Se V, Sr IV-VII, Te VI, and I VI ions [5] in the white dwarfs' G191-B2B and RE 0503-289, the authors calculated the oscillator strengths of the emitted lines and included them in their atmosphere-model calculations.…”

Section: Introductionmentioning

confidence: 99%

Radiative, collisional atomic and Stark broadening data for Ar XII and Ar XIV ions: Quantum mechanical calculations

Aloui

Elabidi

Sahal‐Bréchot

2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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We present in this work Stark broadening calculations for 12 Ar XII and 12 Ar XIV lines. We present also their radiative atomic and collision data (energy levels, radiative decay rates, line strengths, oscillator strengths and collision strengths). Our Stark broadening data have been obtained using our quantum method in the impact approximation frame and including fine structure effects in the structure study. Our results are provided for the range of temperatures from 5×10 5 to 5×10 6 K of interest for plasmas investigations, and at electron density N e = 10 18 cm −3 . The radiative atomic data have been calculated using the UCL code SUPERSTRUCTURE. The collision strengths have been calculated using the two UCL codes DISTORTED WAVE and JAJOM. Good agreement have been found between our atomic results and other theoretical and experimental ones. Our Stark broadening data are the first to be published, so no comparisons have been performed for them.

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“…Contrary to Doppler broadening, Stark broadening depends on the electron density, and then there is a significant difference between Stark and Doppler broadening in white dwarf atmospheres (Aloui et al 2019a). 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.…”

Section: Introductionmentioning

confidence: 99%

“…We focus in the present work on two ions: firstly Br VI, lines of which have been detected in the spectrum of the DO white dwarfs RE 05030-289 and HD 149499 B (Werner et al 2018a), and secondly Kr V-VII ions, lines of which have been detected for the first time in the far ultraviolet (FUV) spectrum of the DO white dwarf RE 05030-289 (Werner et al 2012;Rauch et al 2016b). Spectra have been taken with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope (HST).…”

Section: Introductionmentioning

confidence: 99%

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

Elabidi

2021

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Context. This paper provides missing Stark broadening of the Br VI and Kr V-VII lines recently discovered in the ultraviolet spectrum of the hot white dwarf RE 0503–289 and investigates the importance of the Stark broadening mechanism versus the Doppler mechanism in that star. As far as we know, this is the first time that Stark widths of Br VI and Kr V-VII lines have been calculated. Aims. The recent discovery of new lines of Br VI and Kr V-VII encourages us to provide their Stark broadening to enrich the STARK-B database and for use in interpretations of the observed spectra. Methods. We used our quantum mechanical method for calculating electron impact broadening to provide Stark widths. The method starts with an evaluation of the structure and collision parameters using the University College London codes SUPERSTRUCTURE/DISTORTED WAVE/JAJOM, which are adapted to the line broadening calculations. We then used the collision parameters to calculate the line widths using our programs. Results. We provide the missing widths of 35 lines of Br VI and Kr V-VII at different electron temperatures and at density Ne = 1017 cm−3. We find that the Stark broadening mechanism is preponderant compared to the Doppler one for almost all the plasma conditions of the considered DO white dwarf atmospheres.

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First detection of bromine and antimony in hot stars

Cited by 20 publications

References 27 publications

Heavy metals in intermediate He-rich hot subdwarfs: the chemical composition of HZ 44 and HD 127493

Heavy metals in intermediate He-rich hot subdwarfs: the chemical composition of HZ 44 and HD 127493

Radiative, collisional atomic and Stark broadening data for Ar XII and Ar XIV ions: Quantum mechanical calculations

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

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