Models and mode identifications of the δ Scuti star FG Vir

Guzik, J. A.; Bradley, P. A.

doi:10.1515/astro-1995-0404

Cited by 8 publications

(8 citation statements)

References 5 publications

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“…This is one of the largest numbers of detected frequencies for a single δ Scuti star. The presence of some gravity modes has already been reported by Breger et al (1995) and Guzik and Bradley (1995). Some more g modes, with possible regular spacing, might have been detected in these new observations.…”

Section: Introductionsupporting

confidence: 79%

“…Garrido et ai (1990) have shown that these can be used reliably to discriminate between radial and nonradial modes of low radial order and low degree. Guzik and Bradley (1995) have computed models for FG Vir, and compared their results to those from Breger et al (1995), obtained from Dziembowski's evolution and pulsation codes. The slight differences between Dziembowski's codes, and Guzik and Bradley's, result in nonradial frequencies which can differ by several μΗζ.…”

Section: First Mode Identificationmentioning

confidence: 99%

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Observational asteroseismology of δ Scuti stars

Breger

Audard

1997

Symp. - Int. Astron. Union

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Abstract. Ground-based observational networks are now able to reliably detect more than 20 frequencies for individual δ Scuti stars. The groundbased Delta Scuti Network specializes in the intensive study of individual stars for several months with dedicated telescopes on different continents. With the new quantity and quality of data, the observational limit to extracting 50 or more frequencies in a single δ Scuti star is no longer determined only by the signal/noise ratio, but by the available frequency resolution.Recent results on the δ Scuti stars FG Vir and 4CVn are presented. 4CVn exhibits some of the characteristics of δ Scuti stars: some close spacings are observed, pulsations occur in specific frequency regions with relatively sharp borders, and show large amplitude variations. This presents an important asteroseismological diagnostic, and can help us to improve our understanding of for example rotation and excitation mechanisms.We also report a new Gamma Doradus variable with two excited g modes (HD 108100, F2V).

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Section: Introductionsupporting

confidence: 79%

Section: First Mode Identificationmentioning

confidence: 99%

Observational asteroseismology of δ Scuti stars

Breger

Audard

1997

Symp. - Int. Astron. Union

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“…In spite of efforts (e.g. Breger et al 1995;Guzik & Bradley 1995;Viskum et al 1998;Breger et al 1999;Templeton et al 2001), we still do not have a good seismic model of this object. Not much has been learnt so far from this rich frequency data.…”

Section: Introductionmentioning

confidence: 88%

Inferences from pulsational amplitudes and phases for multimodeδSct star FG Vir

Daszyńska‐Daszkiewicz

Dziembowski

Pamyatnykh

et al. 2005

A&A

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Abstract.We combine photometric and spectroscopic data on twelve modes excited in FG Vir to determine their spherical harmonic degrees , and to obtain constraints on the star model. The effective temperature consistent with the mean colours and the pulsation data is about 7200 K. In six cases, the identification is unique with above 80% probability. Two modes are identified as radial. Simultaneously with , we determine a complex parameter f which probes subphotospheric stellar layers. Comparing its values with those derived from models assuming different treatment of convection, we find evidence that convective transport in the envelope of this star is inefficient.

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“…Perhaps the most advanced are the models of the white dwarfs PG1159-035 (Kawaler & Bradley, 1994) and GD 358 (Bradley & Winget, 1994). Models of the δ Scuti stars: GX Peg (Goupil et al, 1993) and FG Vir (Guzik & Bradley, 1995) as well as that of the β Cep star EN Lac (Dziembowski & Jerzykiewicz, 1996) are crude and based on inadequate treatment of the effects of rotation on oscillation frequencies. Typical equatorial velocities of rotation in δ Set and β Cep stars are in the range 50-200 km/s.…”

Section: Seismic Stellar Modelsmentioning

confidence: 99%

Sounding stellar interiors

Dziembowski

1997

Symp. - Int. Astron. Union

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Multimode pulsations have been discovered in a large variety of main sequence stars and white dwarfs. There are abundant and accurate data on p- and g- mode frequencies in these objects. So far, however, use of these data for sounding interiors has been very limited. The main obstacle is the difficulty in identification of detected modes that is in assignment of spherical harmonic degree, l, azimuthal order, m, and radial order, n, to the modes detected in power spectra of variable stars. This has never been a problem in helioseismology. Even in the case of whole disc measurements a simple structure of power spectra enables an unambiguous mode identification. Such a situation is very rare in asteroseismology. Perhaps oscillating white dwarfs PG 1159-035 and GD 358 are the only examples. Methods of determining the l and m from observational data on the excited modes are available. However, their implementation to – typically low amplitude – multimode pulsators is difficult. In most cases mode identification cannot be separated from determination of stellar parameters.

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Models and mode identifications of the δ Scuti star FG Vir

Cited by 8 publications

References 5 publications

Observational asteroseismology of δ Scuti stars

Observational asteroseismology of δ Scuti stars

Inferences from pulsational amplitudes and phases for multimodeδSct star FG Vir

Sounding stellar interiors

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