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

Kochukhov, Oleg; Драке, Н. А.; Piskunov, Nikolai; Reza, R. de la

doi:10.1051/0004-6361:20040517

Cited by 111 publications

(150 citation statements)

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“…Further information on the final linelist used for reconstructing abundance maps is given in the Table 2. The observed line profiles were inverted with the invers12 code (Kochukhov et al 2004). The code uses a regularized minimization algorithm and can treat many individual lines and their blends simultaneously.…”

Section: Basic Methodsmentioning

confidence: 99%

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Multi-element Doppler imaging of the CP2 star HD 3980

Nesvacil

Lüftinger

Shulyak

et al. 2012

A&A

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Context. In atmospheres of magnetic main-sequence stars, the diffusion of chemical elements leads to a number of observed anomalies, such as abundance spots across the stellar surface. Aims. The aim of this study was to derive a detailed picture of the surface abundance distribution of the magnetic chemically peculiar star HD 3980. Methods. Based on high-resolution, phase-resolved spectroscopic observations of the magnetic A-type star HD 3980, the inhomogeneous surface distribution of 13 chemical elements (Li, O, Si, Ca, Cr, Mn, Fe, La, Ce, Pr, Nd, Eu, and Gd) has been reconstructed. The INVERS12 code was used to invert the rotational variability in line profiles to elemental surface distributions. Results. Assuming a centered, dominantly dipolar magnetic field configuration, we find that Li, O, Mg, Pr, and Nd are mainly concentrated in the area of the magnetic poles and depleted in the regions around the magnetic equator. The high abundance spots of Si, La, Ce, Eu, and Gd are located between the magnetic poles and the magnetic equator. Except for La, which is clearly depleted in the area of the magnetic poles, no obvious correlation with the magnetic field has been found for these elements otherwise. Ca, Cr, and Fe appear enhanced along the rotational equator and the area around the magnetic poles. The intersection between the magnetic and the rotational equator constitutes an exception, especially for Ca and Cr, which are depleted in that region. Conclusions. No obvious correlation between the theoretically predicted abundance patterns and those determined in this study could be found. This can be attributed to a lack of up-to-date theoretical models, especially for rare earth elements.

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Section: Basic Methodsmentioning

confidence: 99%

“…The code uses a regularized minimization algorithm and can treat many individual lines and their blends simultaneously. A detailed description of the software and some practical applications are given by, e.g., Piskunov & Rice (1993), Lüftinger et al (2010), and Kochukhov et al (2004).…”

Section: Basic Methodsmentioning

confidence: 99%

Multi-element Doppler imaging of the CP2 star HD 3980

Nesvacil

Lüftinger

Shulyak

et al. 2012

A&A

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“…Surface magnetic field moduli of some roAp stars are plotted with respect to the dominant oscillation frequencies. The magnetic field strengths were taken from Shulyak et al (2013), Ryabchikova et al (2008), Mathys et al (1997), Hubrig et al (2005), Kochukhov et al (2004), Balona et al (2013).…”

Section: Hideyuki Saiomentioning

confidence: 99%

Pulsation of magnetic stars

Saio

2013

Proc. IAU

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Abstract. Some Ap stars with strong magnetic fields pulsate in high-order p modes; they are called roAp (rapidly oscillating Ap) stars. The p-mode frequencies are modified by the magnetic fields. Although the large frequency separation is hardly affected, small separations are modified considerably. The magnetic field also affects the latitudinal amplitude distribution on the surface. We discuss the property of axisymmetric p-mode oscillations in roAp stars.Keywords. stars: magnetic fields, stars: oscillations Observational properties of roAp starsThe group of rapidly oscillating Ap (roAp) stars was discovered by Kurtz (1982) more than thirty years ago (it consisted of five members then). Since then, the number of known roAp stars has increased to around 40-50 (still increasing); a recent list is given by Kurtz et al. (2006). They are chemically-peculiar main-sequence stars having masses ranging from ∼ 1.5 to ∼ 2 M ⊙ , and effective temperatures from ∼ 6400 to ∼ 8400 K. On the H-R diagram (Fig 1, left panel), they lie in and around the δ Sct instability strip. However, the oscillation frequencies are much higher than those of δ Sct variables as seen in the right panel of Fig. 1, which plots dominant frequencies of roAp and δ Sct stars with respect to the effective temperature. The roAp stars pulsate in high-order p modes whose frequencies range from ∼ 1 to ∼ 3 mHz (periods; ∼ 6 − 21 min), while δ Sct stars

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“…Vertical and horizontal microscopic diffusion of the chemical elements (Michaud 1970) is thus believed to occur, leading to spotted surfaces that have been reconstructed by Doppler or ZeemanDoppler imaging for several (ro)Ap stars (Lüftinger et al 2003(Lüftinger et al , 2010Kochukhov et al 2004;Kochukhov & Wade 2010). Such abnormal surface layers might generate systematic errors when Article published by EDP Sciences A21, page 1 of 8 A&A 559, A21 (2013) determining stellar luminosities and effective temperatures by spectrometric or photometric techniques (Matthews et al 1999).…”

Section: Introductionmentioning

confidence: 99%

The fundamental parameters of the roAp star 10 Aquilae

Perraut

Borgniet

Cunha

et al. 2013

A&A

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Context. Owing to the strong magnetic field and related abnormal surface layers existing in rapidly oscillating Ap (roAp) stars, systematic errors are likely to be present when determining their effective temperatures, which potentially compromises asteroseismic studies of this class of pulsators. Aims. Using the unique angular resolution provided by long-baseline visible interferometry, our goal is to determine accurate angular diameters of a number of roAp targets, so as to derive unbiased effective temperatures (T eff ) and provide a T eff calibration for these stars. Methods. We obtained long-baseline interferometric observations of 10 Aql with the visible spectrograph VEGA at the combined focus of the CHARA array. We derived the limb-darkened diameter of this roAp star from our visibility measurements. Based on photometric and spectroscopic data available in the literature, we estimated the star's bolometric flux and used it, in combination with its parallax and angular diameter, to determine the star's luminosity and effective temperature. Results. We determined a limb-darkened angular diameter of 0.275 ± 0.009 mas and deduced a linear radius of R = 2.32 ± 0.09 R . For the bolometric flux we considered two datasets, leading to an effective temperature of T eff = 7800 ± 170 K and a luminosity of L/L = 18 ± 1 or T eff = 8000 ± 210 K and L/L = 19 ± 2. Finally we used these fundamental parameters together with the large frequency separation determined by asteroseismic observations to constrain the mass and the age of 10 Aql, using the CESAM stellar evolution code. Assuming a solar chemical composition and ignoring all kinds of diffusion and settling of elements, we obtained a mass M/M ∼ 1.92 and an age of ∼780 Gy or a mass M/M ∼ 1.95 and an age of ∼740 Gy, depending on the derived value of the bolometric flux. Conclusions. For the first time, thanks to the unique capabilities of VEGA, we managed to determine an accurate angular diameter for a star smaller than 0.3 mas and to derive its fundamental parameters. In particular, by only combining our interferometric data and the bolometric flux, we derived an effective temperature that can be compared to those derived from atmosphere models. Such fundamental parameters can help for testing the mechanism responsible for the excitation of the oscillations observed in the magnetic pulsating stars.

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

Cited by 111 publications

References 43 publications

Multi-element Doppler imaging of the CP2 star HD 3980

Multi-element Doppler imaging of the CP2 star HD 3980

Pulsation of magnetic stars

The fundamental parameters of the roAp star 10 Aquilae

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