On the Origin of Neutron-capture Elements in r-I and r-II Stars: A Differential-abundance Analysis
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| Format: | Preprint |
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2025
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| _version_ | 1866911102868127744 |
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| author | Saraf, Pallavi Sivarani, Thirupathi Beers, Timothy C. Hirai, Yutaka Tanaka, Masaomi Prieto, Carlos Allende Karinkuzhi, Drisya |
| author_facet | Saraf, Pallavi Sivarani, Thirupathi Beers, Timothy C. Hirai, Yutaka Tanaka, Masaomi Prieto, Carlos Allende Karinkuzhi, Drisya |
| contents | We present a strictly line-by-line differential analysis of a moderately $r$-process-enhanced star ($r$-I: HD~107752) with respect to a strongly $r$-process-enhanced star ($r$-II: CS~31082-0001) to investigate the possible common origin of their heavy-element nucleosynthesis with high-precision abundances. This study employs ESO data archive high-resolution and high signal-to-noise spectra taken with the UVES (VLT) spectrograph. Considering only the lines in common in both spectra, we estimate differential abundances of 16 light/Fe-peak elements and 15 neutron-capture elements. Abundances of O, Al, Pr, Gd, Dy, Ho, Er, and detection of Tm in HD~107752 are presented for the first time. We found three distinct features in the differential-abundance pattern. Nearly equal abundances of light elements up to Zn are present for both the stars, indicating a common origin for these elements; in addition to no noticable odd-even differential pattern. In the case of neutron-capture elements, the $r$-I star exhibits mildly depleted light $r$-process elements and more depleted heavier $r$-process elements relative to $r$-II star. We also show that among $r$-I and $r$-II stars, the ratio of lighter-to-heavier $r$-process elements (e.g. [(Sr,Y,Zr)/Eu]) exhibits a decreasing trend with respect to the overall $r$-process enhancement, forming a continuous sequence from $r$-I and $r$-II stars. Finally, we discuss the necessity of multiple sites for the formation of $r$-I stars. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2508_08847 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | On the Origin of Neutron-capture Elements in r-I and r-II Stars: A Differential-abundance Analysis Saraf, Pallavi Sivarani, Thirupathi Beers, Timothy C. Hirai, Yutaka Tanaka, Masaomi Prieto, Carlos Allende Karinkuzhi, Drisya Solar and Stellar Astrophysics We present a strictly line-by-line differential analysis of a moderately $r$-process-enhanced star ($r$-I: HD~107752) with respect to a strongly $r$-process-enhanced star ($r$-II: CS~31082-0001) to investigate the possible common origin of their heavy-element nucleosynthesis with high-precision abundances. This study employs ESO data archive high-resolution and high signal-to-noise spectra taken with the UVES (VLT) spectrograph. Considering only the lines in common in both spectra, we estimate differential abundances of 16 light/Fe-peak elements and 15 neutron-capture elements. Abundances of O, Al, Pr, Gd, Dy, Ho, Er, and detection of Tm in HD~107752 are presented for the first time. We found three distinct features in the differential-abundance pattern. Nearly equal abundances of light elements up to Zn are present for both the stars, indicating a common origin for these elements; in addition to no noticable odd-even differential pattern. In the case of neutron-capture elements, the $r$-I star exhibits mildly depleted light $r$-process elements and more depleted heavier $r$-process elements relative to $r$-II star. We also show that among $r$-I and $r$-II stars, the ratio of lighter-to-heavier $r$-process elements (e.g. [(Sr,Y,Zr)/Eu]) exhibits a decreasing trend with respect to the overall $r$-process enhancement, forming a continuous sequence from $r$-I and $r$-II stars. Finally, we discuss the necessity of multiple sites for the formation of $r$-I stars. |
| title | On the Origin of Neutron-capture Elements in r-I and r-II Stars: A Differential-abundance Analysis |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2508.08847 |