Improved Ti II log(gf) Values and Abundance Determinations in the Photospheres of the Metal-Poor Star HD 84937

TL;DR

This paper reports improved atomic transition probabilities for Ti II lines, leading to more accurate titanium abundance measurements in the Sun and the metal-poor star HD 84937, enhancing our understanding of stellar compositions.

Contribution

It provides new, more precise Ti II transition probabilities using advanced spectrometry, reducing systematic errors and improving stellar abundance determinations.

Findings

Ti II transition probabilities are more accurate.

Ti abundances in the Sun and HD 84937 are consistent with previous studies.

Supports the trend of Ti/Fe ratio versus metallicity.

Abstract

Atomic transition probability measurements for 364 lines of Ti II in the UV through near IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrometer are combined with published radiative lifetimes to determine these transition probabilities. The new results are in generally good agreement with previously reported FTS measurements. Use of the new echelle spectrometer, independent radiometric calibration methods, and independent data analysis routines enables a reduction of systematic errors and overall improvement in transition probability accuracy over previous measurements. The new Ti II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ti abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. The Ti abundances derived using Ti II for these two stars match those derived using Ti I and support the relative Ti/Fe abundance ratio versus metallicity seen in previous studies.