High-resolution Spectroscopy and Spectropolarimetry of Selected Delta Scuti Pulsating Variables

Abstract

The combination of photometry, spectroscopy and spectropolarimetry of the chemically peculiar stars often aims to study the complex physical phenomena such as stellar pulsation, chemical inhomogeneity, magnetic field and their interplay with stellar atmosphere and circumstellar environment. The prime objective of the present study is to determine the atmospheric parameters of a set of Am stars to understand their evolutionary status. Atmospheric abundances and basic parameters are determined using full spectrum fitting technique by comparing the high-resolution spectra to the synthetic spectra. To know the evolutionary status we derive the effective temperature and luminosity from different methods and compare them with the literature. The location of these stars in the H-R diagram demonstrate that all the sample stars are evolved from the Zero-Age-Main-Sequence towards Terminal-Age-Main-Sequence and occupy the region of $\delta$ Sct instability strip. The abundance analysis shows that the light elements e.g. Ca and Sc are underabundant while iron peak elements such as Ba, Ce etc. are overabundant and these chemical properties are typical for Am stars. The results obtained from the spectropolarimetric analysis shows that the longitudinal magnetic fields in all the studied stars are negligible that gives further support their Am class of peculiarity.

Accepted for publication in MNRAS

References in corpus (3)

• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy
• Fundamental parameters of 8 Am stars: comparing observations with theory

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• HERMES spectroscopy of normal A and Am stars
• High-precision photometric and high-resolution spectroscopic characterisation of HD 180347
• Chemical abundances and doppler imaging of the Ap Si/He-wk star HD 100357
• Asteroseismology of sz lyn using multi-band high time resolution photometry from ground and space
• Indo-Belgian co-operation in Astrophysics: From inception to future prospects
• High-precision K2/TESS Photometry and HERMES Spectroscopy of Four Bright Field Stars
• Photometric and Spectroscopic Analysis of Five Am Stars