The enigma of lithium in roAp stars

Polosukhina, N. S.; Шаврина, А. В.; Драке, Н. А.; Tsymbal, V.; Hack, Margherita; North, P.; Khalack, V.; Zverko, J.; Ziznovsky, J.; Pavlenko, Ya. V.

doi:10.1017/s1743921305009555

Cited by 8 publications

(15 citation statements)

References 4 publications

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“…We find that T eff = 7650 ± 150 K provides a satisfactory fit to the hydrogen Hα and Hβ line wings. This effective temperature is slightly lower than, but nevertheless consistent with, the T eff = 7750 K adopted in other spectroscopic analyses of HR 3831 (Polosukhina et al 2000). The effective temperature of the star was determined using the phase-averaged profiles of the hydrogen lines.…”

Section: Fundamental Stellar Parameterssupporting

confidence: 81%

“…The results of our Doppler reconstruction of the lithium abundance map -the first Doppler mapping of this element for a peculiar A star -are presented in Fig. 7 and generally confirm the Li map inferred by Polosukhina et al (2000). Moreover, a more detailed nature of our analysis and, possibly, accounting for variable blending with the Pr  6706.70 Å line yielded a higher contrast abundance map showing some deviations from a strictly axisymmetric distribution, as the shapes of the Li spots close to the positive and negative magnetic poles appear to be somewhat different.…”

Section: Light Elementssupporting

confidence: 81%

“…• , and has much higher abundance in the spots, log(N Li /N tot ) ≈ −5.0, compared to the outcome of the trial-and-error spectral modelling (log(N Li /N tot ) = −8.5, Polosukhina et al 2000).…”

Section: Light Elementsmentioning

confidence: 92%

“…Polosukhina et al (2000) attempted to use information provided by this spectral feature in a trial-and-error analysis of the surface Li distribution. They suggested that a reasonably good description of the Li line profile variability can be achieved by assuming that the element is enhanced by ≈2.4 dex relative to the solar abundance in two circular spots (R spot ≈ 30…”

Section: Light Elementsmentioning

confidence: 99%

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Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831

Kochukhov

Драке

Piskunov

et al. 2004

A&A

111

144

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Abstract. We investigate magnetic field geometry and surface distribution of chemical elements in the rapidly oscillating Ap star HR 3831. Results of the model atmosphere analysis of the spectra of this star are combined with the Hipparcos parallax and evolutionary models to obtain new accurate estimates of the fundamental stellar parameters: T eff = 7650 K, log L/L = 1.09, M/M = 1.77 and an inclination angle i = 68• of the stellar axis of rotation. We find that the variation of the longitudinal magnetic field of HR 3831 and the results of our analysis of the magnetic intensification of Fe  lines in the spectrum of this star are consistent with a dipolar magnetic topology with a magnetic obliquity β = 87• and a polar strength B p = 2.5 kG. We apply a multi-element abundance Doppler imaging inversion code for the analysis of the spectrum variability of HR 3831, and recover surface distributions of 17 chemical elements, including Li, C, O, Na, Mg, Si, Ca, Ti, Cr, Mn, Fe, Co, Ba, Y, Pr, Nd, Eu. Our study represents the most thorough examination of the surface chemical structure in a magnetic Ap star and provides important observational constraints for modelling radiative diffusion in magnetic stars. The exceedingly high quality of some of our spectroscopic data allowed us to reconstruct unprecedented details of abundance distributions, demonstrating a high level of complexity in the surface structure down to the resolution limit of the Doppler maps. The Doppler imaging analysis of HR 3831 forms a basis for subsequent detailed observational investigations and theoretical modelling of non-radial oscillations in this star. We discuss the compound effect of the chemical nonuniformities and pulsational velocity field on the rapid line profile variations, and assess the possibility of identifying pulsation modes by using spatial filtering produced by an inhomogeneous abundance distribution. The results of our study of the surface chemical structure suggest that differences in pulsational behaviour of lines of different ions observed for HR 3831 are not a consequence of horizontal atmospheric inhomogeneities, but predominantly a depth effect.

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Section: Fundamental Stellar Parameterssupporting

confidence: 81%

Section: Light Elementssupporting

confidence: 81%

Section: Light Elementsmentioning

confidence: 92%

Section: Light Elementsmentioning

confidence: 99%

See 2 more Smart Citations

Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831

Kochukhov

Драке

Piskunov

et al. 2004

A&A

111

144

View full text Add to dashboard Cite

show abstract

“…North et al (1998) found evidence for Li-rich spots on the surface of the rapidlyoscillating Ap star HD 83368. A detailed study by Polosukhina et al (1999Polosukhina et al ( , 2000 revealed a very strong Li i λ6708 line with significant variations in the intensity and position with rotational phase. The behavior of this line was explained by the existence of two opposite Li-rich spots on the stellar surface using the oblique rotator model.…”

Section: Introductionmentioning

confidence: 99%

The Spotted Li abundance on the surface of the CP star HD 3980

et al. 2004

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Abstract.We report the results of the spectral monitoring of the chemically peculiar (CP2) star HD 3980 in the Li i λ6708 spectral region. High spectral resolution observations (R = 88000) were carried out at Mount Stromlo Observatory with the 74-inch telescope and the echelle spectrograph. HD 3980 is a late type Ap SrCrEu star with strong double-wave photometric variations in the visible and in the near infrared. We estimated the effective temperature, surface gravity, mass, luminosity, and radius of this star. The monitoring of this star shows strong spectral variations, especially in the profile of Li i λ6707.8. We studied the variations of the equivalent width and position of the Li i line as a function of the rotating phase and compared them with the magnetic field variations and light curves taken from the literature. The synchronism of the variations of the Li i line profile, light curve, and magnetic field strength can be explained in terms of the oblique magnetic rotator model. The strong variations of position and intensity of this line with the rotation phase enable us to consider this star as a new member of the intriguing group of "Li-spotted" CP stars.

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The enigma of lithium in roAp-CP stars. Some observational results obtained with different telescopes

Polosukhina¹,

Шаврина

Драке³

et al. 2005

Proc. IAU

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The international Project "Lithium in magnetic CP stars" has been put into operation using telescopes of the Crimean Astrophysical Observatory (2.6-m reflector ZTSH), European Southern Observatory (1.4-m CAT and 1.52-m with FEROS), Mount Stromlo Observatory (74-inch), Nordic Optical Telescope Scientific Association (2.4-m with SOFIN), and Special Astrophysical Observatory of the Russian Academy of Sciences (6-m BTA). Here we present an historical report of the different scientific results of this project since its beginning in 1996.

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The enigma of lithium in roAp stars

Cited by 8 publications

References 4 publications

Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831

Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831

The Spotted Li abundance on the surface of the CP star HD 3980

The enigma of lithium in roAp-CP stars. Some observational results obtained with different telescopes

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