Abundance analysis of prime B-type targets for asteroseismology

Niemczura, E.; Morel, Thierry; Aerts, C.

doi:10.1051/0004-6361/200911931

Cited by 36 publications

(47 citation statements)

References 64 publications

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“…The first scenario deals with the observed relative underabundances of elements with second ionization potentials close to the ionization potential of hydrogen, and the second one explains the dependence of the relative abundances of chemical elements on the condensation temperatures of these elements. We will show the abovementioned dependencies for ρ Pup, δ Sct, several other B-Ftype stars with well-defined abundance patterns, and also for 140 A-F stars from Erspamer & North (2003) and 89 B-A stars investigated by Niemczura et al (2009). Figure 6 shows the relative abundances of chemical elements versus the second ionization potentials (χ) of these elements.…”

Section: Discussionmentioning

confidence: 94%

“…The last accretion scenario is investigated in the atmospheres of B-F-type stars using the best abundance patterns published for δ Sct, HD 65949, HD 175640, f Her, χ Lup, and also the abundances of 140 A-F stars and 89 late B stars investigated by Erspamer & North (2003) and Niemczura et al (2009), respectively. The correlations between the relative and absolute abundances of chemical elements, and also the second ionization potentials versus the condensation temperatures of these elements, and the projected rotational velocities are found.…”

Section: Introductionmentioning

confidence: 99%

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THE CHEMICAL COMPOSITION OFρPUPPIS AND THE SIGNS OF ACCRETION IN THE ATMOSPHERES OF B–F-TYPE STARS

Yushchenko

Gopka

Kang

et al. 2015

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We investigated the chemical composition of ρ Pup using high-resolution spectral observations taken from the Very Large Telescope and the IUE archives and also spectra obtained at the 1.8 m telescope of the Bohyunsan observatory in Korea. The abundances of 56 chemical elements and the upper limits of Li and Be abundances were determined. The abundance pattern of ρ Pup was found to be similar to that of Am-type stars. The possibility of the influence of the accretion of interstellar gas and dust on the abundance patterns of B-F-type stars is discussed. The plots of the relative abundances of chemical elements in the atmospheres of ρ Pup and δ Sct versus the second ionization potentials of these elements show the correlations. The discontinuities at 13.6 and 24.6 eV-the ionization potentials of hydrogen and helium, respectively, are also exhibited in these plots. These discontinuities can be explained by interaction of the atoms of interstellar gas, mainly hydrogen and helium atoms, with the atoms of stellar photospheres (so-called charge-exchange reactions). Note that only the jumps near 13.6 and 24.6 eV were pointed out in previous investigations of relative abundances versus the second ionization potentials for Am-type stars. The dependencies of the relative abundances of chemical elements on the second ionization potentials of these elements were investigated using the published abundance patterns of B-F-type stars. The correlations of relative and absolute abundances of chemical elements, second ionization potentials, and projected rotational velocities are clearly detected for stars with effective temperatures between 7,000 and 12,000 K. If the correlation of relative abundances and second ionization potentials can be explained by the accretion of interstellar gas on the stellar surfaces, the investigation of these correlations can provide valuable information on the density and velocities of interstellar gas in different regions of the Galaxy and also on the influence of this phenomenon on stellar evolution. The dependencies of the relative abundances of chemical elements on the condensation temperatures of these elements were also found in the atmospheres of ρ Pup, δ Sct, and other B-F-type stars. Ten possible λ Boo-type stars were detected. The effective temperatures of these objects are between 10,900 and 14,000 K.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

THE CHEMICAL COMPOSITION OFρPUPPIS AND THE SIGNS OF ACCRETION IN THE ATMOSPHERES OF B–F-TYPE STARS

Yushchenko

Gopka

Kang

et al. 2015

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“…1, and part of the chemical compositions of stars with known abundances are provided in Table 2. In the framework of a preparatory programme for CoRoT (Solano et al 2005), the objects HD 46179, HD 181440, HD 182198 and HD 170935 were analysed spectroscopically by Niemczura et al (2009) and Lefever et al (2010). To obtain a consistent determination of the fundamental parameters (T eff , log g, and E(B − V)) for the whole sample, we fitted Kurucz atmosphere models (Kurucz 1993) to the literature photometry for these stars, assuming the average extinction curve for the Milky Way with R v = 3.1 (Chiar & Tielens 2006) and solar metallicity.…”

Section: Sample Descriptionmentioning

confidence: 99%

“…At least three binaries are included, which is expected Notes. The abundance of an element X is given as log (X), where log (H) = 12 (taken from Niemczura et al 2009). Solar abundances from Asplund et al (2005).…”

Section: Sample Descriptionmentioning

confidence: 99%

CoRoT’s view on variable B8/9 stars: spots versus pulsations

Degroote

Acke

Samadi

et al. 2011

A&A

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Context. There exist few variability studies of stars in the region in the Hertzsprung-Russell diagram between the A and B-star pulsational instability strips. With the aid of the high precision continuous measurements of the CoRoT space satellite, low amplitudes are more easily detected, making a study of this neglected region worthwhile. Aims. We collected a small sample of B stars observed by CoRoT to determine the origin of the different types of variability observed. Methods. We combine literature photometry and spectroscopy to measure the fundamental parameters of the stars in the sample, and compare asteroseismic modelling of the light curves with (differentially rotating) spotted star models. Results. We found strong evidence for the existence of spots and differential rotation in HD 174648, and formulated hypotheses for their origin. We show that the distinction between pulsations and rotational modulation is difficult to make solely based on the light curve, especially in slowly rotating stars.

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“…These two values are supported by the analysis of other metal ions (Ti ii, Cr ii, and Mn ii). We closely followed the methodology presented by Niemczura et al (2009) to determine the chemical abundances.…”

Section: Fundamental Parameters and Chemical Compositionmentioning

confidence: 99%

A search for pulsations in the HgMn star HD 45975 with CoRoT photometry and ground-based spectroscopy

Morel

Briquet

Auvergne

et al. 2013

A&A

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The existence of pulsations in HgMn stars is still being debated. To provide the first unambiguous observational detection of pulsations in this class of chemically peculiar objects, the bright star HD 45975 was monitored for nearly two months by the CoRoT satellite. Independent analyses of the light curve provide evidence of monoperiodic variations with a frequency of 0.7572 d −1 and a peak-topeak amplitude of ∼2800 ppm. Multisite, ground-based spectroscopic observations overlapping the CoRoT observations show the star to be a long-period, single-lined binary. Furthermore, with the notable exception of mercury, they reveal the same periodicity as in photometry in the line moments of chemical species exhibiting strong overabundances (e.g., Mn and Y). In contrast, lines of other elements do not show significant variations. As found in other HgMn stars, the pattern of variability consists in an absorption bump moving redwards across the line profiles. We argue that the photometric and spectroscopic changes are more consistent with an interpretation in terms of rotational modulation of spots at the stellar surface. In this framework, the existence of pulsations producing photometric variations above the ∼50 ppm level is unlikely in HD 45975. This provides strong constraints on the excitation/damping of pulsation modes in this HgMn star.

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Abundance analysis of prime B-type targets for asteroseismology

Cited by 36 publications

References 64 publications

THE CHEMICAL COMPOSITION OFρPUPPIS AND THE SIGNS OF ACCRETION IN THE ATMOSPHERES OF B–F-TYPE STARS

THE CHEMICAL COMPOSITION OFρPUPPIS AND THE SIGNS OF ACCRETION IN THE ATMOSPHERES OF B–F-TYPE STARS

CoRoT’s view on variable B8/9 stars: spots versus pulsations

A search for pulsations in the HgMn star HD 45975 with CoRoT photometry and ground-based spectroscopy

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