Vanadium abundances in early A stars

Abstract

Vanadium-to-hydrogen ratios have been determined for o Peg, HR 6127, HR 465 (rare earth minimum), and HR 8216. With respect to the solar system, vanadium is overabundant in the first two stars, possibly normal in the third, and underabundant in the fourth. The range in the V/H ratio in these four stars is between one and two orders of magnitude. An intercomparison of the four spectra shows that the strong V n lines occur in the stars with weaker Cr and Fe spectra. The vanadium anomaly is thus suggestive of the well-known calcium anomaly in peculiar A stars, but we believe that vanadium and calcium abundances are not closely correlated.

Project VeSElkA: abundance analysis of chemical species in HD 41076 and HD 148330

“…In this case, the Hipparcos B − V color of HD 148330 (ESA 1997) is reduced to (B − V) 0 ≈-0.003 mag and the photometric temperature calibration (Netopil et al 2008) provides for this star its T eff = 9322±180 K, which also is close to our estimate. It should be pointed out that our estimate of effective temperature and the aforementioned results for T eff obtained for this star from photometric calibrations are significantly smaller than the value T eff =9750K derived by Zabriskie (1977) and Cowley et al (1978), but higher than the value T eff =9164K obtained by Mihalas (1970). Nevertheless, our estimate of effective temperature is close to the value T eff = 9400±480 K derived by (Sokolov 1998) from the analysis of slope of the Balmer continuum in spectrum of HD 148330.…”

Abundances and chemical stratification analysis in the atmosphere of Cr-type Ap star HD 204411

“…No vanadium lines are measured in our spectrum. To estimate the vanadium abundance we have used equivalent widths published by Cowley et al (1978). Vanadium is deficient by 0.7 dex compared to the normal A star HD 32115 (Bikmaev et al 2002) and the Sun.…”

Measurements of hyperfine structure in51V II

“…In an earlier study of vanadium abundances in early A stars, Cowley et al [8,9] noted that the strengths of the V II lines varied markedly from star to star, with sharp-lined 'normal' stars having strong V II lines and many Ap stars having weak V II lines. This variation became even stronger if one looked at the ratio of the abundance of V II to other iron peak elements, and is important evidence for understanding the origin of abundance anomalies in Ap stars.…”