Context. Atomic data is crucial for astrophysical investigations. To understand the formation and evolution of stars, we need to analyse their observed spectra. Analysing a spectrum of a star requires information about the properties of atomic lines, such as wavelengths and oscillator strengths. However, atomic data of some elements are scarce, particularly in the infrared region, and this paper is part of an effort to improve the situation on near-IR atomic data. Aims. This paper investigates the spectrum of neutral scandium, Sc i, from laboratory measurements and improves the atomic data of Sc i lines in the infrared region covering lines in R, I, J, and K bands. Especially, we focus on measuring oscillator strengths for Sc i lines connecting the levels with 4p and 4s configurations. Methods. We combined experimental branching fractions with radiative lifetimes from the literature to derive oscillator strengths (f - values). Intensity-calibrated spectra with high spectral resolution were recorded with Fourier transform spectrometer from a hollow cathode discharge lamp. The spectra were used to derive accurate oscillator strengths and wavelengths for Sc i lines, with emphasis on the infrared region. Results. This project provides the first set of experimental Sc i lines in the near-infrared region for accurate spectral analysis of astronomical objects. We derived 63 log(g f ) values for the lines between 5300Å and 24300Å. The uncertainties in the f -values vary from 5% to 20%. The small uncertainties in our values allow for an increased accuracy in astrophysical abundance determinations.
A laboratory plasma experiment for X-ray astronomy using a compact electron beam ion trap (EBIT)
The Institute of Space and Astronautical Science (ISAS), Japan Aerospace and Exploration Agency (JAXA)（宇宙科学研究所，日本宇宙航空研究开发机构）；RIKEN Pioneering Research Institute, RIKEN（理化学研究所先导研究院，理化学研究所）；Department of Physics, The University of Tokyo（东京大学物理学系）；European XFEL（欧洲X射线自由电子激光设施）；Faculty of Engineering, University of Miyazaki（宫崎大学工学部）；National Institute for Fusion Science（国立大学法人核融合科学研究所）；Institute for Laser Science, The University of Electro-Communications（电波研究所激光科学研究所，电气通信大学）；Department of Physics, Rikkyo University（立教大学物理学系）；RIKEN SPring-8 Center, RIKEN（理化学研究所SPring-8中心，理化学研究所）
