Chemical composition of A and F dwarfs members of the Hyades open cluster

Gebran, M.; Vick, M.; Monier, Richard; Fossati, L.

doi:10.1051/0004-6361/200913273

Cited by 73 publications

(100 citation statements)

References 56 publications

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“…Unfortunately, however, no lines of this element are suitable for measurement in our spectra of either system. Nevertheless, the overall abundance pattern in both SW CMa and HW CMa is quite similar to that found in many other studies of Am stars (see, e.g., Okyudo & Sadakane 1990;Hui-Bon-Hoa 2000;Yushchenko et al 2004;Iliev et al 2006;Fossati et al 2007;Gebran et al 2008Gebran et al , 2010.…”

Section: Radial Velocities and Spectroscopic Orbitsupporting

confidence: 88%

Absolute dimensions of eclipsing binaries

Torres

Clausen

Bruntt

et al. 2012

A&A

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Context. Accurate physical properties of eclipsing stars provide important constraints on models of stellar structure and evolution, especially when combined with spectroscopic information on their chemical composition. Empirical calibrations of the data also lead to accurate mass and radius estimates for exoplanet host stars. Finally, accurate data for unusual stellar subtypes, such as Am stars, also help to unravel the cause(s) of their peculiarities. Aims. We aim to determine the masses, radii, effective temperatures, detailed chemical composition and rotational speeds for the Am-type eclipsing binaries SW CMa (A4-5m) and HW CMa (A6m) and compare them with similar normal stars. Methods. Accurate radial velocities from the Digital Speedometers of the Harvard-Smithsonian Center for Astrophysics were combined with previously published uvby photometry to determine precise physical parameters for the four stars. A detailed abundance analysis was performed from high-resolution spectra obtained with the Nordic Optical Telescope (La Palma). Results. We find the masses of the (relatively evolved) stars in SW CMa to be 2.10 and 2.24 M , with radii of 2.50 and 3.01 R , while the (essentially zero-age) stars in HW CMa have masses of 1.72 and 1.78 M , radii of 1.64 and 1.66 R -all with errors well below 2%. Detailed atmospheric abundances for one or both components were determined for 14 elements in SW CMa (

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Section: Radial Velocities and Spectroscopic Orbitsupporting

confidence: 88%

Absolute dimensions of eclipsing binaries

Torres

Clausen

Bruntt

et al. 2012

A&A

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“…However, at the peak of the Balmer jump, it is also very prone to normalisation errors, which could easily be responsible for such small differences in observed line strength. Furthermore, this resonance line is extremely sensitive to the Ca abundance, which even in normal A stars shows large star-to-star scatter (up to 0.6 dex; Gebran et al 2010). From this example we conclude that 300-K discrepancies in T eff are easily introduced when a composite spectrum is interpreted as a single star.…”

Section: Appendix A: Undetected Binariesmentioning

confidence: 69%

A search for non-pulsating, chemically normal stars in the δ Scuti instability strip using Kepler data

Murphy

Bedding

Niemczura

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We identify stars in the δ Sct instability strip that do not pulsate in p modes at the 50-µmag limit, using Kepler data. Spectral classification and abundance analyses from high-resolution spectroscopy allow us to identify chemically peculiar stars, in which the absence of pulsations is not surprising. The remaining stars are chemically normal, yet they are not δ Sct stars. Their lack of observed p modes cannot be explained through any known mechanism. However, they are mostly distributed around the edges of the δ Sct instability strip, which allows for the possibility that they actually lie outside the strip once the uncertainties are taken into account. We investigated the possibility that the non-pulsators inside the instability strip could be unresolved binary systems, having components that both lie outside the instability strip. If misinterpreted as single stars, we found that such binaries could generate temperature discrepancies of ∼300 K -larger than the spectroscopic uncertainties, and fully consistent with the observations. After these considerations, there remains one chemically normal nonpulsator that lies in the middle of the instability strip. This star is a challenge to pulsation theory. However, its existence as the only known star of its kind indicates that such stars are rare. We conclude that the δ Sct instability strip is pure, unless pulsation is shut down by diffusion or another mechanism, which could be interaction with a binary companion.

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“…The line list used for spectral synthesis is the one used in Gebran et al ( , 2010. All transitions between 3000 and 7000 Å from Kurucz's gfall.dat 5 line list are selected for the calculation of the synthetic spectra.…”

Section: Spectrum Synthesismentioning

confidence: 99%

Normal A0−A1 stars with low rotational velocities

Royer

Gebran

Monier

et al. 2014

A&A

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Context. The study of rotational velocity distributions for normal stars requires an accurate spectral characterization of the objects in order to avoid polluting the results with undetected binary or peculiar stars. This piece of information is a key issue in the understanding of the link between rotation and the presence of chemical peculiarities. Aims. A sample of 47 low v sin i A0−A1 stars (v sin i < 65 km s −1 ), initially selected as main-sequence normal stars, are investigated with high-resolution and high signal-to-noise spectroscopic data. The aim is to detect spectroscopic binaries and chemically peculiar stars, and eventually establish a list of confirmed normal stars. Methods. A detailed abundance analysis and spectral synthesis is performed to derive abundances for 14 chemical species. A hierarchical classification, taking measurement errors into account, is applied to the abundance space and splits the sample into two different groups, identified as the chemically peculiar stars and the normal stars. Results. We show that about one third of the sample is actually composed of spectroscopic binaries (12 double-lined and five singlelined spectroscopic binaries). The hierarchical classification breaks down the remaining sample into 13 chemically peculiar stars (or uncertain) and 17 normal stars.

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Chemical composition of A and F dwarfs members of the Hyades open cluster

Cited by 73 publications

References 56 publications

Absolute dimensions of eclipsing binaries

Absolute dimensions of eclipsing binaries

A search for non-pulsating, chemically normal stars in the δ Scuti instability strip using Kepler data

Normal A0−A1 stars with low rotational velocities

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