The calcium isotopic anomaly in magnetic CP stars

Abstract

Chemically peculiar stars in the magnetic sequence can show the same isotopic anomaly in calcium previously discovered for mercury-manganese stars in the non-magnetic sequence. In extreme cases, the dominant isotope is the exotic 48^Ca. Measurements of Ca II lines arising from 3d-4p transitions reveal the anomaly by showing shifts up to 0.2 AA for the extreme cases - too large to be measurement errors. We report measurements of miscellaneous objects, including two metal-poor stars, two apparently normal F-stars, an Am-star, and the N-star U Ant. Demonstrable anomalies are apparent only for the Ap stars. The largest shifts are found in rapidly oscillating Ap stars and in one weakly magnetic Ap star, HD 133792. We note the possible relevance of these shifts for the GAIA mission.

arXiv comment4 pages, 2 figures, accepted for publication as a letter in A&A

References in corpus (4)

• Spectroscopic survey of the Galaxy with Gaia I. Design and performance of the Radial Velocity Spectrometer
• Measurements of magnetic fields over the pulsation cycle in six roAp stars with FORS1 at the VLT
• New measurements of magnetic fields of roAp stars with FORS1 at the VLT
• The Core-Wing Anomaly of Cool Ap Stars: Abnormal Balmer Profiles

Cited by in corpus (11)

• Isotopic anomaly and stratification of Ca in magnetic Ap stars
• Emergence of granular-sized magnetic bubbles through the solar atmosphere. II. Non-LTE chromospheric diagnostics and inversions
• Part-per-billion measurement of the $4^2{S}_{1/2}\to 3^2{D}_{5/2}$ electric quadrupole transition isotope shifts between ${}^{42,44,48}$Ca${}^{+}$ and ${}^{40}$Ca${}^{+}$
• The effect of isotopic splitting on the bisector and inversions of the solar Ca II 854.2 nm line
• Unexpectedly large difference of the electron density at the nucleus in the 4p ${}^2$P${}_{1/2,3/2}$ fine-structure doublet of Ca${}^{+}$
• Heavy Calcium in CP Stars
• A high resolution study of isotopic composition and chemical abundances of blue horizontal branch stars in the globular clusters NGC6397 and NGC6752
• Stratification and Isotope Separation in CP Stars
• NLTE spectroscopic analysis of the ${}^3$He anomaly in subluminous B-type stars
• 3D non-LTE Ca II line formation in metal-poor FGK stars. I. Abundance corrections, radial velocity corrections, and synthetic spectra
• High resolution spectroscopy of HgMn stars: a time of surprises