Near-infrared spectra of chemically peculiar stars and applications to kilonova spectra

@misc{domoto2026nearinfrared,
  title = {{Near-infrared spectra of chemically peculiar stars and applications to kilonova spectra}},
  author = {Nanae Domoto and Masaomi Tanaka and Wako Aoki and Salma Rahmouni and Tomoyuki Kudo and Hiroki Harakawa and Teruyuki Hirano and Takayuki Kotani and Takashi Kurokawa and Masayuki Kuzuhara and Jun Nishikawa and Takuma Serizawa and Motohide Tamura and Akitoshi Ueda},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.30835},
  eprint = {2609.30835},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.30835},
}

TY  - UNPB
TI  - Near-infrared spectra of chemically peculiar stars and applications to kilonova spectra
AU  - Nanae Domoto
AU  - Masaomi Tanaka
AU  - Wako Aoki
AU  - Salma Rahmouni
AU  - Tomoyuki Kudo
AU  - Hiroki Harakawa
AU  - Teruyuki Hirano
AU  - Takayuki Kotani
AU  - Takashi Kurokawa
AU  - Masayuki Kuzuhara
AU  - Jun Nishikawa
AU  - Takuma Serizawa
AU  - Motohide Tamura
AU  - Akitoshi Ueda
PY  - 2026
DA  - 2026/09/25
PB  - arXiv
DO  - 10.48550/arxiv.2609.30835
UR  - https://arxiv.org/abs/2609.30835
AB  - Kilonova spectra provide information on rapid neutron-capture nucleosynthesis in neutron star mergers. However, it remains challenging to identify individual elements in kilonova spectra, primarily due to incomplete atomic data for heavy elements at near-infrared wavelengths. Recent work demonstrated that spectra of chemically peculiar stars offer excellent laboratory for studying kilonova spectra. In this paper, to expand our understanding of strong transitions of heavy elements at near-infrared wavelengths, we present high-resolution near-infrared spectra of 14 chemically peculiar stars covering a range of effective temperatures, surface gravities, and abundance patterns, obtained with Subaru/IRD. The Sr II, Ce III, and Gd III lines, previously suggested to be among the strongest transitions, are detected in the spectra of most of our targets, confirming their intrinsic importance. In addition, Eu II and Nd III lines are detected in several stars. By comparing observed equivalent widths and abundance ratios, we show that under a highly heavy-element-enriched abundance pattern, Eu II and Nd III lines may contribute to kilonova spectral features comparably to Sr II. Importantly, we find no unidentified lines systematically stronger than these transitions despite the larger stellar sample. These results further support the primary importance of the Sr II and Ce III transitions and provide new insights into the potential contribution of Eu II and Nd III.
ER  -