Fe i Lines in 0.91–1.33 μm Spectra of Red Giants for Measuring the Microturbulence and Metallicities

Kondo, Sohei; Fukue, Kei; Matsunaga, Noriyuki; Ikeda, Yuji; Taniguchi, Daisuke; Kobayashi, Naoto; Sameshima, Hiroaki; Hamano, Satoshi; Arai, Akira; Kawakita, Hideyo; Yasui, Chikako; Izumi, Natsuko; Mizumoto, Misaki; Otsubo, Shogo; Takenaka, Keiichi; Watase, Ayaka; Asano, Akira; Yoshikawa, Tomohiro; Tsujimoto, Takuji

Abstract

For a detailed analysis of stellar chemical abundances, high-resolution spectra in the optical have mainly been used, while the development of near-infrared (NIR) spectrograph has opened new wavelength windows. Red giants have a large number of resolved absorption lines in both the optical and NIR wavelengths, but the characteristics of the lines in different wave passbands are not necessarily the same. We present a selection of Fe I lines in the z′, Y, and J bands (0.91–1.33 μm). On the basis of two different lists of lines in this range, the Vienna Atomic Line Database (VALD) and the catalog published by Meléndez & Barbuy in 1999 (MB99), we selected sufficiently strong lines that are not severely blended and compiled lists with 107 Fe I lines in total (97 and 75 lines from VALD and MB99, respectively). Combining our lists with high-resolution (λ/Δλ=28,000) and high signal-tonoise (>500) spectra taken with an NIR spectrograph, WINERED, we present measurements of the iron abundances of two prototype red giants: Arcturus and μLeo. A bootstrap method for determining the microturbulence and abundance together with their errors is demonstrated. The standard deviations of log Fe values from individual Fe I lines are significantly smaller when we use the lines from MB99 instead of those from VALD. With the MB99 list, we obtained x = 1.20  0.11 km s-1 and log Fe = 7.01  0.05 dex for Arcturus, and x = 1.54  0.17 km s-1 and log Fe = 7.73  0.07 dex for μLeo. These final values show better agreements with previous values in the literature than the corresponding values we obtained with VALD.

Citation

Kondo, S., Fukue, K., Matsunaga, N., Ikeda, Y., Taniguchi, D., Kobayashi, N., …Tsujimoto, T. (2019). Fe i Lines in 0.91–1.33 μm Spectra of Red Giants for Measuring the Microturbulence and Metallicities. Astrophysical Journal, 875(2), https://doi.org/10.3847/1538-4357/ab0ec4

• Journal Article Type: Article
• Acceptance Date: Mar 3, 2019
• Online Publication Date: Apr 23, 2019
• Publication Date: Apr 23, 2019
• Deposit Date: May 10, 2019
• Publicly Available Date: May 10, 2019
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 875
• Issue: 2
• DOI: https://doi.org/10.3847/1538-4357/ab0ec4
• Public URL: https://durham-repository.worktribe.com/output/1301731