References of "Leaflet - Astronomical Society of the Pacific"
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See detailHigh-resolution spectropolarimetric observations of hot subdwarfs
Petit, P.; Van Grootel, Valérie ULg; Bagnulo, S. et al

in Leaflet - Astronomical Society of the Pacific (2012, March 01), 452

We report on high-resolution spectropolarimetric observations of the hot subdwarf stars HD 76431 and Feige 66, using the ESPaDOnS echelle spectropolarimeter at CFHT. We compute cross-correlation Stokes I ... [more ▼]

We report on high-resolution spectropolarimetric observations of the hot subdwarf stars HD 76431 and Feige 66, using the ESPaDOnS echelle spectropolarimeter at CFHT. We compute cross-correlation Stokes I and V line profiles to enhance the signal-to-noise ratio. We then average all available cross-correlation profiles of each star to further decrease the noise level. Although both targets were previously reported to host kilo-gauss magnetic fields, we do not derive any evidence of large-scale photospheric fields from our sets of observations, in spite of tight error bars on the longitudinal field of the order of 60 gauss for HD 76431 and 200 gauss for Feige 66. A new analysis of FORS1 observations of HD 76431, which provided the basis for the original claim of field detection, confirms the absence of any detectable Zeeman signature, with an error bar of about 100 gauss on the longitudinal magnetic field. [less ▲]

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See detailAsteroseismic Solutions for the Two Fast Subdwarf B Pulsators Balloon 090100001 and PG 1336-018
Charpinet, Stéphane; Van Grootel, Valérie ULg; Brassard, Pierre et al

in Leaflet - Astronomical Society of the Pacific (2008, January), 392

We present two new asteroseismic studies of the rapid sdB pulsator PG 1336-018 and the hybrid sdB pulsator Balloon (BAL) 090100001. For PG 1336-018, the analysis is based on 25 periods extracted from the ... [more ▼]

We present two new asteroseismic studies of the rapid sdB pulsator PG 1336-018 and the hybrid sdB pulsator Balloon (BAL) 090100001. For PG 1336-018, the analysis is based on 25 periods extracted from the white-light photometry of the Xcov17 Whole Earth Telescope campaign (Kilkenny et al. 2003). For BAL 090100001, we use 10 periods of high amplitudes for which constraints on the ℓ-index have been derived from high S/N multicolour photometry. From asteroseismology, we estimate important structural parameters for these two stars, including the stellar mass and the H-rich envelope thickness. The analyses presented here are of particular interest since the asteroseismic results can be tested using independent constraints, which confirm the robustness of the solutions in both cases. [less ▲]

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See detailAchievements and Challenges in the Field of sdB Asteroseismology
Fontaine, Gilles; Charpinet, Stéphane; Green, Elizabeth M. et al

in Leaflet - Astronomical Society of the Pacific (2008, January), 392

We review briefly the status of sdB star asteroseismology. We concentrate on the main achievements that have been obtained so far, and we discuss the current challenges that we now face in the field.

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See detailAn Asteroseismological Analysis of the Pulsating B Subdwarf Feige 48 Taking into Account Rotation
Van Grootel, Valérie ULg; Charpinet, Stéphane; Fontaine, Gilles et al

in Leaflet - Astronomical Society of the Pacific (2008, January), 392

We present a new analysis of the short period pulsating sdB star Feige 48 using the same observations as done in our previous work, but exploiting, this time, our new period-matching codes that include ... [more ▼]

We present a new analysis of the short period pulsating sdB star Feige 48 using the same observations as done in our previous work, but exploiting, this time, our new period-matching codes that include the rotation of the star. The pulsation spectrum of Feige 48 shows the signature of rotational splitting with a mean frequency spacing of about 28 μHz between the components of three different frequency multiplets. In addition, Feige 48 has been shown to be a member of a close binary system with an invisible (most likely a white dwarf) companion. Assuming various internal rotation laws, we are now able to fit all nine observed frequencies simultaneously, and not only the four m = 0 components that we identified a priori in our previous effort. For solid body rotation, our optimal model shows slightly different structural parameters than those obtained previously on the basis of purely spherical models. Interestingly, that optimal model is also characterized by a rotation period of 9.028 h, which falls exactly on the value of the orbital period found independently from spectroscopy, namely, 9.024 ± 0.072 h. This very strongly implies that Feige 48 is tidally locked, a suggestion quite consistent with theoretical expectations for such a close binary system. In the same vein, our investigations also demonstrate explicitly that the idea of a fast rotating core can be eliminated for Feige 48. [less ▲]

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See detailAn Asteroseismological Study of the Rapidly Pulsating Subdwarf B Star PG 0911+456
Randall, Suzanna K.; Green, Elizabeth M.; Van Grootel, Valérie ULg et al

in Leaflet - Astronomical Society of the Pacific (2008, January), 392

We present the analysis and interpretation of 57 hours of time-series photometry obtained with the new Mont4kccd on Mt. Bigelow, Arizona, for the rapidly pulsating sdB star PG 0911+456. Thanks to the ... [more ▼]

We present the analysis and interpretation of 57 hours of time-series photometry obtained with the new Mont4kccd on Mt. Bigelow, Arizona, for the rapidly pulsating sdB star PG 0911+456. Thanks to the impressively high S/N of the data we were able to extract 7 independent periodicities in the 140-200 s range with amplitudes down to 0.05 % of the mean stellar brightness. On the basis of these we performed an asteroseismological search for the optimal model and derived the star's fundamental parameters. Given that there are now 12 sdB stars for which asteroseismology has been performed, the results are starting to become significant from a statistical point of view and evolutionary trends are slowly emerging. [less ▲]

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See detailConstraints on Seismic Models of Balloon 090100001 through High-Sensitivity Multicolour Photometry
Charpinet, Stéphane; Fontaine, Gilles; Brassard, Pierre et al

in Leaflet - Astronomical Society of the Pacific (2008, January), 392

We report on an analysis of high S/N ratio UBV multicolour photometry of the bright pulsating sdB star Balloon 090100001 gathered at the Canada-France-Hawaii Telescope with the help of the Montreal 3 ... [more ▼]

We report on an analysis of high S/N ratio UBV multicolour photometry of the bright pulsating sdB star Balloon 090100001 gathered at the Canada-France-Hawaii Telescope with the help of the Montreal 3-channel photometer LAPOUNE. Through an application of the color-amplitude method described in Randall et al. (2005), we were able to identify the degree index ℓ of several individual pulsation modes. These identifications provide extremely useful constraints on possible seismic models for Balloon 090100001. [less ▲]

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See detailAstrophysics and industry
Swings, Polydore ULg

in Leaflet - Astronomical Society of the Pacific (1953), 6(286), 283-290

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See detailAstrophysics: 1951
Swings, Polydore ULg

in Leaflet - Astronomical Society of the Pacific (1952), 6(273), 178-188

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See detailFluorescence in astronomy
Swings, Polydore ULg

in Leaflet - Astronomical Society of the Pacific (1943), 4(175), 192-198

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