Abundances and search for vertical stratification in the atmospheres of four HgMn stars

Thiam, Mouhamadou; Leblanc, F.; Khalack, V.; Wade, G. A.

doi:10.1111/j.1365-2966.2010.16539.x

Cited by 20 publications

(32 citation statements)

References 43 publications

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“…The comparison with the abundances by Thiam et al (2010) has shown close agreement between the two determinations. Because Thiam et al (2010) use an ATLAS9 model computed for solar abundances, the ATLAS12 model computed for an individual abundance may be estimated as unnecessary.…”

Section: Model Parameters and Abundances Of Hd 71066supporting

confidence: 48%

“…Previous studies of HD 71066 (κ 2 Vol, HR 3302) have pointed out the isotopic anomaly of Hg (Dolk et al 2003;Thiam et al 2010). No vertical abundance stratification for Ti, Cr, and Fe is found by Thiam et al (2010).…”

Section: The Hgmn Star Hd 71066mentioning

confidence: 96%

“…No vertical abundance stratification for Ti, Cr, and Fe is found by Thiam et al (2010). No presence of magnetic field is found both from the inspection of the equivalent widths of the Fe ii lines at 6147.7 Å and 6149.2 Å (Hubrig et al 1999) and after using the FORS 1 spectropolarimeter at the VLT (Hubrig et al 2006).…”

Section: The Hgmn Star Hd 71066mentioning

confidence: 99%

“…To be consistent with the other papers, we present here an abundance analysis of HD 71066, which was studied with the same methods as adopted for the other stars. A previous work on HD 71066, related to vertical abundance stratification in HgMn stars, was performed by Thiam et al (2010), who adopted the same observations as are used in this paper. We note, however, that no mention about Xe ii was made in their study.…”

Section: Introductionmentioning

confidence: 99%

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Wavelengths and oscillator strengths of Xe II from the UVES spectra of four HgMn stars

Yüce

Castelli

Hubrig

2011

A&A

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Aims. In spite of large overabundances of Xe ii observed in numerous mercury-manganese (HgMn) stars, Xe ii oscillator strengths are only available for a very limited number of transitions. As a consequence, several unidentified lines in the spectra of HgMn stars could be due to Xe ii. In addition, some predicted Xe ii lines are redshifted by about 0.1 Å from stellar unidentified lines, raising the question about the wavelength accuracy of the Xe ii line data available in the literature. For these reasons we investigated the Xe ii lines lying in the 3900-4521 Å, 4769-7542 Å, and 7660-8000 Å spectral ranges of four well-studied HgMn stars. Methods. We compared the Xe ii wavelengths listed in the NIST database with the position of the lines observed in the high-resolution UVES spectrum of the xenon-overabundant, slowly rotating HgMn star HR 6000, and we modified them when needed. We derived astrophysical oscillator strengths for all the Xe ii observed lines and compared them with the literature values, when available. We checked the stellar atomic data derived from HR 6000 by using them to compute synthetic spectra for three other xenon-overabundant, slowly rotating HgMn stars, HD 71066, 46 Aql, and HD 175640. In this framework, we performed a complete abundance analysis of HD 71066, while we relied on our previous works for the other stars. Results. We find that all the lines with wavelengths related to the 6d and 7s energy levels have a corresponding unidentified spectral line, blueshifted by the same quantity of about 0.1 Å in all the four stars, so that we identified these lines as coming from Xe ii and modified their NIST wavelength value according to the observed stellar value. We find that the Xe ii stellar oscillator strengths may differ from one star to another from 0.0 dex to 0.3 dex. We adopted the average of the oscillator strengths derived from the four stars as final astrophysical oscillator strength.

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Section: Model Parameters and Abundances Of Hd 71066supporting

confidence: 48%

Section: The Hgmn Star Hd 71066mentioning

confidence: 96%

Section: The Hgmn Star Hd 71066mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Wavelengths and oscillator strengths of Xe II from the UVES spectra of four HgMn stars

Yüce

Castelli

Hubrig

2011

A&A

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“…Although there is no compelling observational evidence of this phenomenon in HgMn stars (Savanov & Hubrig 2003;Thiam et al 2010;Makaganiuk et al 2012), an accumulation at different layers is supported by theoretical calculations (Sect. 4).…”

Section: Fundamental Parameters and Chemical Compositionmentioning

confidence: 83%

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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Atomic diffusion and element mixing in pulsating stars

Alecian¹

2013

Proc. IAU

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Stellar plasmas are multicomponent anisotropic gases. Each component (chemical element) of these gases experiences specific forces related to its properties, which leads each element to diffuse with respect to the others. There is no reason why a stellar plasma should remain homogeneous except if mixing motions enforce homogeneity. Because atomic diffusion is a very slow process, the element separation only occurs in places where mixing motions are weak enough not to erase the effect of the ineluctable tendency of chemical elements to migrate. In this talk, I will present how atomic diffusion and mixing processes compete in stars (interiors as well as atmospheres), and I will show various cases where atomic diffusion is believed to have noticeable effects. This concerns several types of stars throughout the H-R diagram, including pulsating ones.

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Abundances and search for vertical stratification in the atmospheres of four HgMn stars

Cited by 20 publications

References 43 publications

Wavelengths and oscillator strengths of Xe II from the UVES spectra of four HgMn stars

Wavelengths and oscillator strengths of Xe II from the UVES spectra of four HgMn stars

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

Atomic diffusion and element mixing in pulsating stars

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