Astrochemistry

Spectroscopic Determination Of C, N, and O Abundances Of Solar-Analog Stars Based On The Lines Of Hydride Molecules

By Keith Cowing
Press Release
astro-ph.GA
December 14, 2022
Filed under ,
Spectroscopic Determination Of C, N, and O Abundances Of Solar-Analog Stars Based On The Lines Of Hydride Molecules
The results of C, N, and O abundances for the Sun (A ; logarithmic number abundance in the usual normalization of AH = 12), which were derived from the fitting analysis of solar (Vesta) spectrum in each region, are plotted against the corresponding region number. The left, middle, and right panels are for C, N, and O, respectively. The reference solar CNO abundances published by Anders & Grevesse (1989) (8.56, 8.05, 8.93) and Asplund et al. (2009) (8.43, 7.83, 8.69) are indicated by the horizontal dashed and solid lines, respectively. — astro-ph.GA

Photospheric C, N, and O abundances of 118 solar-analog stars were determined by applying the synthetic-fitting analysis to their spectra in the blue or near-UV region comprising lines of CH, NH, and OH molecules, with an aim of clarifying the behaviors of these abundances in comparison with [Fe/H].

It turned out that, in the range of -0.6<[Fe/H]<+0.3, [C/Fe] shows a marginally increasing tendency with decreasing [Fe/H] with a slight upturn around [Fe/H]~0, [N/Fe] tends to somewhat decrease towards lower [Fe/H], and [O/Fe] systematically increases (and thus [C/O] decreases) with a decrease in [Fe/H]. While these results are qualitatively consistent with previous determinations mostly based on atomic lines, the distribution centers of these [C/Fe], [N/Fe], and [O/Fe] at the near-solar metallicity are slightly negative by several hundredths dex, which is interpreted as due to unusual solar abundances possibly related to the planetary formation of our solar system.

However, clear anomalies are not observed in the [C,N,O/Fe] ratios of planet-host stars. Three out of four very Be-deficient stars were found to show anomalous [C/Fe] or [N/Fe] which may be due to mass transfer from the evolved companion, though its relation to Be depletion mechanism is still unclear.

Yoichi Takeda

Comments: 18 pages (including 7 figures and 4 tables) with online materials; accepted for publication in Research in Astronomy and Astrophysics
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2212.05842 [astro-ph.SR] (or arXiv:2212.05842v1 [astro-ph.SR] for this version)
Submission history
From: Yoichi Takeda
[v1] Mon, 12 Dec 2022 11:59:48 UTC (9,296 KB)
https://arxiv.org/abs/2212.05842
Astrobiology, Astrochemistry

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.