分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2024-01-09 合作期刊: 《Research in Astronomy and Astrophysics》
摘要: HD 222925 is a rare r-process enhanced star in the Milky Way because of its metal abundance ([Fe/H] =−1.46 ± 0.10) and Eu abundance ([Eu/Fe] = 1.32 ± 0.08). Based on the very complete set of elemental abundances of HD 222925, we use the abundance decomposition method to fit the observed abundances of 58 elements in the sample star, which is also the largest number of elemental abundances fitted at the same time for a fixed star. We analyze the astrophysical origins of elements in HD 222925 by its abundance ratios and component ratios. It is found that the light elements and the iron group elements in HD 222925 mainly originate from the primary process of the Type II supernovae (SNe II) with the progenitor mass M > 10 M⊙ and have no contribution from SNe Ia and the first generation of very massive stars. The contribution of the weak r-process to Ga, Ge, and As is superior to that of the other processes, and its contribution decreases linearly with increasing atomic number. The main r-process that is likely derived from a neutron star merger plays a key role in the formation of neutron-capture elements (Z ≥ 38) in HD 222925.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: LAMOST-MRS-B is one of the sub-surveys of LAMOST medium-resolution (R~7500) spectroscopic survey. It aims at studying the statistical properties (e.g., binary fraction, orbital period distribution, mass ratio distribution) of binary stars and exotic stars. We intend to observe about 30000 stars (10 mag = 10, respectively. Most of the sources are B-, A-, and F-type stars with 0.6 < [Fe/H] < 0.4 dex. We also obtain 347 identified variable and exotic stars and about 250 stars with [Fe/H] < 1 dex. We measure radial velocities (RVs) by using 892233 spectra of the stars. The uncertainties of RV achieve about 1 km/s and 10 km/s1 for 95% of late- and early-type stars, respectively. The datasets presented in this paper are available at http://www.doi.org/10.57760/sciencedb.j00113.00035.