Slowly Rotating Peculiar Star BD+001659 as a Benchmark for Stratification Studies in Ap/Bp Stars
arXiv:2409.17855 · doi:10.3390/galaxies12050055
Abstract
We present the results of a self-consistent analysis of the magnetic silicon star BD+001659, based on its high-resolution spectra taken from the ESPaDOnS archive (R = 68,000). This narrow-lined star shows the typical high Si abundance and Si II-III anomaly, making it an ideal prototype for investigating the vertical distribution of Si and Fe in the stellar atmosphere. The derived abundances, ranging from helium to lanthanides, confirm the star's classification as a silicon Bp spectral type. Silicon and iron are represented by lines of different ionisation stages (Fe I-III, Si I-III), indicating an ionisation imbalance interpreted as evidence of atmospheric stratification. Our stratification analysis reveals that there is a jump in iron and silicon abundances of 1.5 dex at atmospheric layers with an optical depth of = 0.85-1.00. Non-LTE calculations for iron in this stratified atmosphere show minor non-LTE effects. Our results can be applied to studying the impact of stratification on the emergent flux in rapidly rotating Si stars with similar atmospheric parameters and abundance anomalies (for example, MX TrA), where direct stratification analysis is challenging due to line~blending.
arXiv comment13 pages, 10 figures, 2 tables
References in corpus (18)
- Astrophysical parameters of Galactic open clusters
- An Analysis of the Shapes of Interstellar Extinction Curves. VII. Milky Way Spectrophotometric Optical-through-Ultraviolet Extinction and Its R-Dependence
- Testing common classical LTE and NLTE model atmosphere and line-formation codes for quantitative spectroscopy of early-type stars
- Hyperfine Splitting in the VALD Database of Spectral-line Parameters
- NLTE line formation for Mg\ione\ and Mg\ii\ in atmospheres of B-A-F-G-K stars
- Abundances determined using Si II and Si III in B-type stars: evidence for stratification
- Non-LTE line formation for Si I-II-III in A-B stars and the origin of Si II emission lines in iota Her
- A self-consistent empirical model atmosphere, abundance and stratification analysis of the benchmark roAp star alpha Circini
- Non-LTE Sodium Abundance in Galactic Thick- and Thin-Disk Red Giants
- Non-LTE line formation for Pr II and Pr III in A and Ap stars
- NLTE carbon abundance determination in selected A- and B-type stars and the interpretation of C\ione\ emission lines
- A NLTE line formation for neutral and singly-ionised calcium in model atmospheres of B-F stars
- Chemical diversity among A-B stars with low rotational velocities: non-LTE abundance analysis
- Influence of Collisions with Hydrogen on Titanium Abundance Determinations in Cool Stars
- The Lorentz force in atmospheres of CP stars: 56 Arietis
- Neon Abundances of B-stars in the Solar Neighborhood
- Doppler imaging of a southern ApSi star HD 152564
- NLTE abundances of C, O, Ca, Ti, and Fe in the reference BAF-type stars