Rotational velocities of A-type stars

Royer, F.; Grenier, S.; Baylac, M.-O.; Gómez, A. E.; Zorec, J.

doi:10.1051/0004-6361:20020943

Cited by 229 publications

(249 citation statements)

References 23 publications

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“…Unfortunately, because of the quite large v sin i (about 124 km s −1 for both components, see Royer et al 2002) even at the maximum radial velocity separation (30 June-1 July) the two components are never completely separated. Figure 1 shows the LSD profiles of all the 16 spectra compared with an extracted region of the spectra.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Spectroscopic search forg-mode pulsations inψCentauri

Mantegazza¹,

Rainer²,

Antonello³

2010

A&A

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Context. Prior analysis of the light curve of the eclipsing binary ψ Cen has shown the possible presence of g-mode pulsations. Aims. We will try to confirm this claim by means of the analysis of high-resolution and high signal-to-noise echelle spectrograms. Methods. We studied both the radial velocity curve and the line profile variations of ψ Cen. Results. We obtained accurate measurements of the masses and radii of the two components. Regarding the study of pulsations, the orbital motion of the stars can explain all the observed variations in the spectrograms. Conclusions. There is no evidence of g-mode pulsations in ψ Cen in the spectroscopic data.

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Section: Observations and Data Reductionmentioning

confidence: 99%

Spectroscopic search forg-mode pulsations inψCentauri

Mantegazza¹,

Rainer²,

Antonello³

2010

A&A

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“…For HD 81009 we used r = 0.64, determined by Landstreet & Mathys (2000). The v sin i values have been measured on our spectra or taken from published spectroscopic studies (Abt 2001;Abt, Levato & Grosso 2002;Bagnulo et al 2002;Balona & Laney 2003;Bohlender, Landstreet & Thompson 1993;Hensberge et al 1979;Landstreet 1970;Landstreet & Mathys 2000;Levato et al 1996;Nielsen & Wahlgren 2002;Royer et al 2002;Wade et al 2000). We could not find in the literature values of v sin i for three stars: HD 54118, HD 73340 and HD 133880.…”

Section: The Magnetic Field Geometrymentioning

confidence: 99%

Evolution of magnetic fields in stars across the upper main sequence: II. Observed distribution of the magnetic field geometry

Hubrig¹,

North

Schöller

2007

Astron Nachr

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We re-discuss the evolutionary state of upper main sequence magnetic stars using a sample of Ap and Bp stars with accurate Hipparcos parallaxes and definitely determined longitudinal magnetic fields. We confirm our previous results obtained from the study of Ap and Bp stars with accurate measurements of the mean magnetic field modulus and mean quadratic magnetic fields that magnetic stars of mass M < 3 M are concentrated towards the centre of the main-sequence band. In contrast, stars with masses M > 3 M seem to be concentrated closer to the ZAMS. The study of a few known members of nearby open clusters with accurate Hipparcos parallaxes confirms these conclusions. Stronger magnetic fields tend to be found in hotter, younger and more massive stars, as well as in stars with shorter rotation periods. The longest rotation periods are found only in stars which spent already more than 40% of their main sequence life, in the mass domain between 1.8 and 3 M and with log g values ranging from 3.80 to 4.13. No evidence is found for any loss of angular momentum during the main-sequence life. The magnetic flux remains constant over the stellar life time on the main sequence. An excess of stars with large obliquities β is detected in both higher and lower mass stars. It is quite possible that the angle β becomes close to 0 • in slower rotating stars of mass M > 3 M too, analog to the behaviour of angles β in slowly rotating stars of M < 3 M . The obliquity angle distribution as inferred from the distribution of r-values appears random at the time magnetic stars become observable on the H-R diagram. After quite a short time spent on the main sequence, the obliquity angle β tends to reach values close to either 90 • or 0 • for M < 3 M . The evolution of the obliquity angle β seems to be somewhat different for low and high mass stars. While we find a strong hint for an increase of β with the elapsed time on the main sequence for stars with M > 3 M , no similar trend is found for stars with M < 3 M . However, the predominance of high values of β at advanced ages in these stars is notable. As the physics governing the processes taking place in magnetised atmospheres remains poorly understood, magnetic field properties have to be considered in the framework of dynamo or fossil field theories.

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“…In order to construct a calibration curve FWHM−v sin i, we have used an average spectrum of HD 27962, acquired with the same instrumentation. Since the rotational velocity of HD 27962 is very low but not zero (v sin i 11 km s −1 , e.g., Royer et al 2004 and references therein), it could be considered as a useful template for A-type stars rotating faster than v sin i 10 km s −1 . The spectrum of HD 27962 was synthetically broadened by convolution with rotational profiles of increasing v sin i in steps of 5 km s −1 and the cross-correlation with the original one was performed at each step.…”

Section: Hjdmentioning

confidence: 99%

A spectroscopic study of the close eclipsing binary HS Herculis

Çakırlı

İbanoǧlu

Frasca³

2007

A&A

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Aims. New high-resolution spectroscopic observations of the eclipsing binary HS Herculis are presented. The main aims were to determine the stellar parameters of the two components, their evolutionary stage, and to search for spectroscopic evidence for a possible third body. Methods. Using the cross-correlation technique, we detect spectroscopically the faint secondary component of HS Herculis, and for the firts time measure its radial velocity. The primary and secondary radial velocity curves are analyzed simultaneously and the results of the orbital solution are combined with those derived from multiband light curve analysis to derive orbital and stellar parameters. Results. We find the masses to be M 1 = 4.49± 0.16 and M 2 = 1.75± 0.09 M , the radii to be R 1 = 2.83± 0.04 and R 2 = 1.61± 0.02 R , and the effective temperatures to be T 1 = 15 200 ± 750 K and T 2 = 7600 ± 400 K for the primary and secondary stars, respectively. We also derive projected rotational velocities of the components as v 1 sin i = 81 ± 3 and v 2 sin i = 24 ± 6. Conclusions. While a synchronous rotation for the primary star is indicated by the broadening of the spectral lines, the secondary component appears to rotate more slowly, nearly one half the synchronous rotation velocity. This discrepancy indicates that the less massive secondary component could have not yet attained tidal synchronization. Although the presence of a third body physically bound to the eclipsing pair has been suggested by many investigators, we find no sign of its presence in our CCD spectra. The evolutionary stage of the system's components is briefly discussed by comparing their physical parameters with those of theoretical models. We find that the two components are located near the zero-age main sequence, with an age of about 32 Myr.

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Rotational velocities of A-type stars

Cited by 229 publications

References 23 publications

Spectroscopic search forg-mode pulsations inψCentauri

Spectroscopic search forg-mode pulsations inψCentauri

Evolution of magnetic fields in stars across the upper main sequence: II. Observed distribution of the magnetic field geometry

A spectroscopic study of the close eclipsing binary HS Herculis

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