HD 12098 -A new northern hemisphere roAp star

Girish, V.; Seetha, S.; Martinez, Peter; Joshi, Santosh; Ashoka, B. N.; Kurtz, D. W.; Chaubey, U. S.; Gupta, S. K.; Sagar, Ram

doi:10.1051/0004-6361:20011132

Cited by 23 publications

(25 citation statements)

References 22 publications

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“…HD 12098 was discovered to be a pulsating Ap star by Girish et al (2001). The authors proposed a 1.22 d rotation period based on a frequency analysis of the photometric pulsations.…”

Section: Hd 12098mentioning

confidence: 99%

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Rotational periods of four roAp stars

Ryabchikova

Wade

Aurière

et al. 2005

A&A

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Abstract. Forty-five new measurements of the mean longitudinal magnetic fields and mean equivalent widths of 4 roAp stars have obtained using the MuSiCoS spectropolarimeter at Pic du Midi observatory. These new high-precision data have been combined with archival measurements in order to constrain the rotational periods of HD 12098, HD 24712 = HR 1217, HD 122970 and HD 176232 = 10 Aql. We report a revised rotational period for HD 24712 (P rot = 12.45877 ± 0.00016 d, crucial for interpretation of upcoming MOST observations of this star), new rotational periods for HD 12098 and HD 122970 (P rot = 5.460 ± 0.001 d and P rot = 3.877 ± 0.001 d, respectively) and evidence for an extremely long period for HD 176232.

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“…HD 12098 was discovered to be a pulsating Ap star by Girish et al (2001). The authors proposed a 1.22 d rotation period based on a frequency analysis of the photometric pulsations.…”

Section: Hd 12098mentioning

confidence: 99%

“…Using the derived ephemeris, we have phased the photometric pulsation amplitudes of Girish et al (2001) according to the rotation period (Fig. 2, bottom panel).…”

Section: Hd 12098mentioning

confidence: 99%

Rotational periods of four roAp stars

Ryabchikova

Wade

Aurière

et al. 2005

A&A

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“…Up to now, more than 30 roAp stars have been detected (Kurtz 1982;Martinez et al 1991;Kurtz et al 1994;Martinez et al 1994;Girish et al 2001;Elkin et al 2005). Their oscillations are characterized by high frequencies, with periods between 4 and 16 min: they are interpreted as high order, low degree acoustic modes.…”

Section: Introductionmentioning

confidence: 99%

Helium settling and mass loss in magnetic Ap stars

Théado

Vauclair

Cunha

2005

A&A

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The chemical stratification is likely to play a predominant role in the excitation mechanism of high order modes in rapidly oscillating Ap stars. In this paper we discuss some processes (convection, He settling, mass loss and turbulent mixing) which may strongly affect the chemical composition of Ap stars. We discuss their interplay with a dipolar magnetic field in both magnetic polar and equatorial regions, where the magnetic lines are respectively mainly radially and horizontally oriented. We also present stellar evolutionary computations for magnetic Ap stars. As the magnetic geometry strongly breaks the sphericity of the star, we modeled and computed the polar and equatorial regions separately. We examine the effects of various chemical transport processes on the chemical stratification of both regions. In a forthcoming paper, we will study the stability of these models against pulsations.

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“…Until now, 35 roAp stars have been detected (Kurtz 1982;Martinez et al 1991;Kurtz et al 1994;Girish et al 2001;Elkin et al 2005). Their rapid pulsations are interpreted as high-overtone, low degree, non-radial p-modes.…”

Section: The Roap Starsmentioning

confidence: 99%

New light on the driving mechanism in roAp stars

Théado

Dupret

Noels

et al. 2008

A&A

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Context. Observations suggest that a relationship exists between the driving mechanism of roAp star pulsations and the heavy element distribution in these stars. Aims. We attempt to study the effects of local and global metallicity variations on the excitation mechanism of high order p-modes in A star models. Methods. We developed stellar evolutionary models to describe magnetic A stars with different global metallicity or local metal accumulation profiles. These models were computed with CLES ("Code Liègeois d'évolution stellaire"), and the stability of our models was assessed with the non-adiabatic oscillation code MAD. Results. Our models reproduce the blue edge of the roAp star instability strip, but generate a red edge hotter than the observed one, regardless of metallicity. Surprisingly, we find that an increase in opacity inside the driving region can produce a lower amount of driving, which we refer to as the "inverse κ-mechanism".

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HD 12098 -A new northern hemisphere roAp star

Cited by 23 publications

References 22 publications

Rotational periods of four roAp stars

Rotational periods of four roAp stars

Helium settling and mass loss in magnetic Ap stars

New light on the driving mechanism in roAp stars

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