References of "Mathys, G"
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See detailMagnetic fields in massive stars
Hubrig, S.; Scholler, M.; Briquet, Maryline ULg et al

in Contributions of the Astronomical Observatory Skalnaté Pleso (2008), 38

We review the recent discoveries of magnetic fields in different types of massive stars and briefly discuss strategies for spectropolarimetric observations to be carried out in the future.

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See detailDiscovery of Magnetic Fields in Slowly Pulsating B Stars
Hubrig, S.; Briquet, Maryline ULg; Schöller, M. et al

in Active OB-Stars: Laboratories for Stellar and Circumstellar Physics, ASP Conference Series, Vol. 361, Proceedings of the conference held 29 August - 2 September, 2005 at Hokkai-Gakuen University, Sapporo, Japan. (2007, March 01)

We present the first observations and conclusions of a magnetic survey with FORS 1 at the VLT of a sample of 25 Slowly Pulsating B stars. A clear mean longitudinal magnetic field of the order of a few ... [more ▼]

We present the first observations and conclusions of a magnetic survey with FORS 1 at the VLT of a sample of 25 Slowly Pulsating B stars. A clear mean longitudinal magnetic field of the order of a few hundred Gauss was detected in eleven SPBs. Among them several SPBs show a magnetic field that varies in time. It becomes clear that SPBs cannot be regarded anymore as non-magnetic stars. [less ▲]

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See detailDiscovery of magnetic fields in the βCephei star ξ1 CMa and in several slowly pulsating B stars*
Hubrig, S.; Briquet, Maryline ULg; Schöller, M. et al

in Monthly Notices of the Royal Astronomical Society (2006), 369

We present the results of a magnetic survey of a sample of eight βCephei stars and 26 slowly pulsating B (SPBs) stars with the FOcal Reducer low dispersion Spectrograph at the Very Large Telescope. A weak ... [more ▼]

We present the results of a magnetic survey of a sample of eight βCephei stars and 26 slowly pulsating B (SPBs) stars with the FOcal Reducer low dispersion Spectrograph at the Very Large Telescope. A weak mean longitudinal magnetic field of the order of a few hundred Gauss is detected in the βCephei star ξ[SUP]1[/SUP]CMa and in 13 SPB stars. The star ξ[SUP]1[/SUP]CMa becomes the third magnetic star among the βCephei stars. Before our study, the star ζCas was the only known magnetic SPB star. All magnetic SPB stars for which we gathered several magnetic field measurements show a field that varies in time. We do not find a relation between the evolution of the magnetic field with stellar age in our small sample. Our observations imply that βCephei and SPB stars can no longer be considered as classes of non-magnetic pulsators, but the effect of the fields on the oscillation properties remains to be studied. [less ▲]

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See detailVariations of the Ap star HDE 318107
Manfroid, Jean ULg; Mathys, G.

in Astronomy and Astrophysics (2000), 364

The rotation period of the Ap star HDE 318107 has been determined from magnetic and photometric observations obtained between August 1992 and September 1998.

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See detailGeneva photometry of HDE 318107 (Manfroid+, 2000)
Manfroid, Jean ULg; Mathys, G.

Report (2000)

File table1 contains the individual photometric measurements of HDE 318107 in the Geneva system. (1 data file).

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See detailThe mean magnetic field modulus of AP stars
Mathys, G.; Hubrig, S.; Landstreet, J. D. et al

in Astronomy and Astrophysics. Supplement Series (1997), 123

We present new measurements of the mean magnetic field modulus of a sample of Ap stars with spectral lines resolved into magnetically split components. We report the discovery of 16 new stars having this ... [more ▼]

We present new measurements of the mean magnetic field modulus of a sample of Ap stars with spectral lines resolved into magnetically split components. We report the discovery of 16 new stars having this property. This brings the total number of such stars known to 42. We have performed more than 750 measurements of the mean field modulus of 40 of these 42 stars, between May 1988 and August 1995. The best of them have an estimated accuracy of 25 - 30 G. The availability of such a large number of measurements allows us to discuss for the first time the distribution of the field modulus intensities. A most intriguing result is the apparent existence of a sharp cutoff at the low end of this distribution, since no star with a field modulus (averaged over the rotation period) smaller than 2.8 kG has been found in this study. For more than one third of the studied stars, enough field determinations well distributed throughout the stellar rotation cycle have been achieved to allow us to characterize at least to some extent the variations of the field modulus. These variations are often significantly anharmonic, and it is not unusual for their extrema not to coincide in phase with the extrema of the longitudinal field (for the few stars for which enough data exist about the latter). This, together with considerations on the distribution of the relative amplitude of variation of the studied stars, supports the recently emerging evidence for markedly non-dipolar geometry and fine structure of the magnetic fields of most Ap stars. New or improved determinations of the rotation periods of 9 Ap stars have been achieved from the analysis of the variations of their mean magnetic field modulus. Tentative values of the period have been derived for 5 additional stars, and lower limits have been established for 10 stars. The shortest definite rotation period of an Ap star with magnetically resolved lines is 3.4 deg, while those stars that rotate slowest appear to have periods in excess of 70 or 75 years. As a result of this study, the number of known Ap stars with rotation periods longer than 30 days is almost doubled. We briefly rediscuss the slow-rotation tail of the period distribution of Ap stars. This study also yielded the discovery of radial velocity variations in 8 stars. There seems to be a deficiency of binaries with short orbital periods among Ap stars with magnetically resolved lines. Based on observations collected at the European Southern Observatory (La Silla, Chile; ESO programmes Nos. 43.7-004, 44.7-012, 49.7-030, 50.7-067, 51.7-041, 52.7-063, 53.7-028, 54.E-0416, and 55.E-0751), at the Observatoire de Haute-Provence (Saint-Michel-l'Observatoire, France), at Kitt Peak National Observatory, and at the Canada-France-Hawaii Telescope. Tables 2, 3, and 4 are also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html. [less ▲]

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See detailVariations of the AP star HD 208217.
Manfroid, Jean ULg; Mathys, G.

in Astronomy and Astrophysics (1997), 320

We present a new determination of the rotation period of the Ap star HD 208217 based on photometric and magnetic measurements. The variations of this star are remarkable by the strong anharmonicity of its ... [more ▼]

We present a new determination of the rotation period of the Ap star HD 208217 based on photometric and magnetic measurements. The variations of this star are remarkable by the strong anharmonicity of its lightcurves in all colours as well as by the double wave of its mean magnetic field modulus variations. [less ▲]

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See detailThe European working group on chemically peculiar stars of the upper main sequence. The first 10 years.
Mathys, G.; Maitzen, H. M.; North, P. et al

in The Messenger (1989), 55

A fraction of the Band A type stars have chemical peculiarities (CP). 4 subgroups are recognized: CP 1 or Am, CP2 or magnetic Ap (with enhanced Sr, Cr, Eu, Si lines), CP3 (ar non-magnetic Ap, with Hg Mn ... [more ▼]

A fraction of the Band A type stars have chemical peculiarities (CP). 4 subgroups are recognized: CP 1 or Am, CP2 or magnetic Ap (with enhanced Sr, Cr, Eu, Si lines), CP3 (ar non-magnetic Ap, with Hg Mn enhanced) and CP4 (B type stars with He peculiarities, a fraction of them appear to be a hot extension of CP 2). [less ▲]

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See detailPhotometric variability of some CP stars
Heck, A.; Mathys, G.; Manfroid, Jean ULg

in Astronomy and Astrophysics. Supplement Series (1987), 70

The photometric data relative to twenty-three southern CP stars have been re-analysed. New or improved parameters of the lightcurves are presented for eleven of them.

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See detailPhotometric variability of southern CP stars
Manfroid, Jean ULg; Mathys, G.

in Astronomy and Astrophysics. Supplement Series (1986), 64

The photometric behavior of eight southern CP stars with relatively large amplitudes of variation is analyzed. Periods of variation and parameters of the light curves are obtained by least-squares fitting ... [more ▼]

The photometric behavior of eight southern CP stars with relatively large amplitudes of variation is analyzed. Periods of variation and parameters of the light curves are obtained by least-squares fitting. A wide variety is found in the periods and in the shapes of the light curves, confirming the lack of correlation between these parameters and the amplitudes. [less ▲]

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See detailPhotometric variability of some early-type stars
Mathys, G.; Manfroid, Jean ULg; Renson, Pierre ULg

in Astronomy and Astrophysics. Supplement Series (1986), 63

Photometric observations of 12 variable early type stars are presented. The properties of individual stars are discussed, and an attempt is made to interpret their variability. The information presented ... [more ▼]

Photometric observations of 12 variable early type stars are presented. The properties of individual stars are discussed, and an attempt is made to interpret their variability. The information presented on the stars includes the HD number and other identification, the observing runs, the periodicity of the variations, an error estimate, and a tentative classification of each star. [less ▲]

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See detailIs HD 23878 A Mild CP Star?
Mathys, G.; Manfroid, Jean ULg; Heck, A.

in Information Bulletin on Variable Stars (1985), 2738

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See detailOn the shape of the UVBY lightcurves of CP stars
Mathys, G.; Manfroid, Jean ULg

in Astronomy and Astrophysics. Supplement Series (1985), 60

The authors present the lightcurves in the Strömgren system of 56 CP stars. The observational data have been fitted by a sine wave and its first harmonic. The least-square parameters are tabulated and it ... [more ▼]

The authors present the lightcurves in the Strömgren system of 56 CP stars. The observational data have been fitted by a sine wave and its first harmonic. The least-square parameters are tabulated and it is shown that such a fit describes very well the CP variations in most cases, the only exceptions being due to observational uncertainties. [less ▲]

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See detailPhotometric variations of HD 25267
Manfroid, Jean ULg; Mathys, G.; Heck, A.

in Astronomy and Astrophysics (1985), 144

Two periodicities are found in the photometric variations of HD 25267. One of the periods (1.2 d) seems to be the same as the magnetic period and is thus attributed to a CP component. The origin of the ... [more ▼]

Two periodicities are found in the photometric variations of HD 25267. One of the periods (1.2 d) seems to be the same as the magnetic period and is thus attributed to a CP component. The origin of the variations with the second period (3.8 d) remains uncertain. [less ▲]

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See detailNew period determinations for variable CP stars
Manfroid, Jean ULg; Mathys, G.

in Astronomy and Astrophysics. Supplement Series (1985), 59

Periods, or improved determinations of periods, are presented for 29 CP stars observed at La Silla in 1977-1982. The PHOT2 program's algorithm makes possible the bringing together of different observing ... [more ▼]

Periods, or improved determinations of periods, are presented for 29 CP stars observed at La Silla in 1977-1982. The PHOT2 program's algorithm makes possible the bringing together of different observing runs, through an improved reduction of the data to a common standard system. It is noted that, in many instances, magnetic observations would be required for the resolution of ambiguities, especially in the presence of quasi-symmetric double waves. [less ▲]

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See detailOn the He Weak Variable HD 28843
Manfroid, Jean ULg; Mathys, G.; Cousins, A. W. J.

in Information Bulletin on Variable Stars (1984), 2625

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See detailThe Bright Eclipsing Binary HD 208496
Manfroid, Jean ULg; Mathys, G.

in Information Bulletin on Variable Stars (1984), 2616

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See detailOn the Photometric Variations of HD 28843 and HD 29009
Manfroid, Jean ULg; Mathys, G.

in Information Bulletin on Variable Stars (1984), 2551

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See detailEclipsing Ap Stars
Renson, Pierre ULg; Mathys, G.

in Information Bulletin on Variable Stars (1984), 2522

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See detailPériode photométriqe de l'étoile Ap HR 3831
Renson, Pierre ULg; Manfroid, Jean ULg; Heck, A. et al

in Astronomy and Astrophysics (1984), 131

From 32 observations made in February 1977, in the uvby system, a photometric period P = 1.428 + or - 0.005 day was previously found for the A7p SrCrEu star HR 3831 = HD 83368. A series of 26 measurements ... [more ▼]

From 32 observations made in February 1977, in the uvby system, a photometric period P = 1.428 + or - 0.005 day was previously found for the A7p SrCrEu star HR 3831 = HD 83368. A series of 26 measurements in December 1975, a few measurements in December 1978, both also in the Stromgren system, and the measurements recently published by Kurtz (1982) in B and V (Johnson system) improve the precision on P. The value obtained is P = 1.42602 + or - 0.00006 day. The photometric variations with this period are displayed. As found previously, a null-wavelength appears in the blue. Kurtz's suggestion that the photometric period is equal to twice the value above does not seem to be justified; however, other considerations favor a rotation period equal to twice the photometric one. [less ▲]

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