Chemical abundances and doppler imaging of the Ap Si/He-wk star HD 100357
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| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Dileep, Athul Joshi, Santosh Alexeeva, Sofya Kochukhov, Oleg Semenko, Eugene De Cat, Peter Zúñiga-Fernández, Sebastián Trust, Otto Pollard, Karen Crause, Lisa Barkaoui, Khalid Gillon, Michaël Jehin, Emmanuel Rathore, Neeraj |
| author_facet | Dileep, Athul Joshi, Santosh Alexeeva, Sofya Kochukhov, Oleg Semenko, Eugene De Cat, Peter Zúñiga-Fernández, Sebastián Trust, Otto Pollard, Karen Crause, Lisa Barkaoui, Khalid Gillon, Michaël Jehin, Emmanuel Rathore, Neeraj |
| contents | We present the results of time-resolved photometry, abundance analysis and Doppler imaging of an Ap star, HD 100357. The {\it TESS} photometry revealed rotational modulation with a period of 1.6279247 days. Upon inspecting the residuals after removing the rotational period and its harmonics, we found additional frequencies around 15.8054 d$^{-1}$ which we later confirmed with ground-based observations as originating from a nearby star. Using high-resolution spectroscopy, we identified HD 100357 as an Ap Si/He-wk star exhibiting rotational modulation caused by surface abundance spots. The stellar parameters of HD 100357 were determined as $T_{\rm eff}$ = 11,850 K, $\log g$ = 4.57, $\upsilon\sin i$ = 60 km\,s$^{-1}$, and an inclination angle $i$ = 72$^{\circ}$. The detailed abundance analysis revealed strongly overabundant stratified silicon, an overabundance of iron-peak elements and rare earth elements combined with remarkably deficient helium. Mapping of Fe and Cr abundances revealed the existence of ring-shaped regions with a lower concentration of the elements. Their geometry might reflect the orientation of the hypothetical magnetic field of the star, oriented $\sim$90$^{\circ}$ to the rotational axis. HD 100357, with its strong chemical peculiarities and indications of possible magnetic fields, represents an interesting candidate for follow-up spectropolarimetric observations aimed at investigating its magnetic field topology and stellar activity. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2508_20682 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Chemical abundances and doppler imaging of the Ap Si/He-wk star HD 100357 Dileep, Athul Joshi, Santosh Alexeeva, Sofya Kochukhov, Oleg Semenko, Eugene De Cat, Peter Zúñiga-Fernández, Sebastián Trust, Otto Pollard, Karen Crause, Lisa Barkaoui, Khalid Gillon, Michaël Jehin, Emmanuel Rathore, Neeraj Solar and Stellar Astrophysics We present the results of time-resolved photometry, abundance analysis and Doppler imaging of an Ap star, HD 100357. The {\it TESS} photometry revealed rotational modulation with a period of 1.6279247 days. Upon inspecting the residuals after removing the rotational period and its harmonics, we found additional frequencies around 15.8054 d$^{-1}$ which we later confirmed with ground-based observations as originating from a nearby star. Using high-resolution spectroscopy, we identified HD 100357 as an Ap Si/He-wk star exhibiting rotational modulation caused by surface abundance spots. The stellar parameters of HD 100357 were determined as $T_{\rm eff}$ = 11,850 K, $\log g$ = 4.57, $\upsilon\sin i$ = 60 km\,s$^{-1}$, and an inclination angle $i$ = 72$^{\circ}$. The detailed abundance analysis revealed strongly overabundant stratified silicon, an overabundance of iron-peak elements and rare earth elements combined with remarkably deficient helium. Mapping of Fe and Cr abundances revealed the existence of ring-shaped regions with a lower concentration of the elements. Their geometry might reflect the orientation of the hypothetical magnetic field of the star, oriented $\sim$90$^{\circ}$ to the rotational axis. HD 100357, with its strong chemical peculiarities and indications of possible magnetic fields, represents an interesting candidate for follow-up spectropolarimetric observations aimed at investigating its magnetic field topology and stellar activity. |
| title | Chemical abundances and doppler imaging of the Ap Si/He-wk star HD 100357 |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2508.20682 |