References of "Weiss, W. W"
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See detailAmplitudes and lifetimes of solar-like oscillations observed by CoRoT. Red-giant versus main-sequence stars
Baudin, F.; Barban, C.; Belkacem, K. et al

in Astronomy and Astrophysics (2011), 529

Context. The advent of space-borne missions such as CoRoT or Kepler providing photometric data has brought new possibilities for asteroseismology across the H-R diagram. Solar-like oscillations are now ... [more ▼]

Context. The advent of space-borne missions such as CoRoT or Kepler providing photometric data has brought new possibilities for asteroseismology across the H-R diagram. Solar-like oscillations are now observed in many stars, including red giants and main-sequence stars. Aims: Based on several hundred identified pulsating red giants, we aim to characterize their oscillation amplitudes and widths. These observables are compared with those of main-sequence stars in order to test trends and scaling laws for these parameters for main-sequence stars and red giants. Methods: An automated fitting procedure is used to analyze several hundred Fourier spectra. For each star, a modeled spectrum is fitted to the observed oscillation spectrum, and mode parameters are derived. Results: Amplitudes and widths of red-giant solar-like oscillations are estimated for several hundred modes of oscillation. Amplitudes are relatively high (several hundred ppm) and widths relatively small (very few tenths of a μHz). Conclusions: Widths measured in main-sequence stars show a different variation with the effective temperature from red giants. A single scaling law is derived for mode amplitudes of red giants and main-sequence stars versus their luminosity to mass ratio. However, our results suggest that two regimes may also be compatible with the observations. [less ▲]

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See detailNon-radial oscillations in the red giant HR 7349 measured by CoRoT
Carrier, F.; De Ridder, J.; Baudin, F. et al

in Astronomy and Astrophysics (2010), 509

Context. Convection in red giant stars excites resonant acoustic waves whose frequencies depend on the sound speed inside the star, which in turn depends on the properties of the stellar interior ... [more ▼]

Context. Convection in red giant stars excites resonant acoustic waves whose frequencies depend on the sound speed inside the star, which in turn depends on the properties of the stellar interior. Therefore, asteroseismology is the most robust available method for probing the internal structure of red giant stars. <BR /> Aims: Solar-like oscillations in the red giant HR 7349 are investigated. <BR /> Methods: Our study is based on a time series of 380 760 photometric measurements spread over 5 months obtained with the CoRoT satellite. Mode parameters were estimated using maximum likelihood estimation of the power spectrum. <BR /> Results: The power spectrum of the high-precision time series clearly exhibits several identifiable peaks between 19 and 40 μHz showing regularity with a mean large and small spacing of Πν = 3.47 ± 0.12 μHz and δν[SUB]02[/SUB] = 0.65 ± 0.10 μHz. Nineteen individual modes are identified with amplitudes in the range from 35 to 115 ppm. The mode damping time is estimated to be 14.7[SUP]+4.7[/SUP][SUB]-2.9[/SUB] days. The CoRoT space mission has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA, Germany and Spain. [less ▲]

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See detailCoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data
Degroote, P.; Aerts, C.; Ollivier, M. et al

in Astronomy and Astrophysics (2009), 506

Context: We search for new variable B-type pulsators in the CoRoT data assembled primarily for planet detection, as part of CoRoT's additional programme. <BR />Aims: We aim to explore the properties of ... [more ▼]

Context: We search for new variable B-type pulsators in the CoRoT data assembled primarily for planet detection, as part of CoRoT's additional programme. <BR />Aims: We aim to explore the properties of newly discovered B-type pulsators from the uninterrupted CoRoT space-based photometry and to compare them with known members of the β Cep and slowly pulsating B star (SPB) classes. <BR />Methods: We developed automated data analysis tools that include algorithms for jump correction, light-curve detrending, frequency detection, frequency combination search, and for frequency and period spacing searches. <BR />Results: Besides numerous new, classical, slowly pulsating B stars, we find evidence for a new class of low-amplitude B-type pulsators between the SPB and δ Sct instability strips, with a very broad range of frequencies and low amplitudes, as well as several slowly pulsating B stars with residual excess power at frequencies typically a factor three above their expected g-mode frequencies. <BR />Conclusions: The frequency data we obtained for numerous new B-type pulsators represent an appropriate starting point for further theoretical analyses of these stars, once their effective temperature, gravity, rotation velocity, and abundances will be derived spectroscopically in the framework of an ongoing FLAMES survey at the VLT. The CoRoT space mission was developed and is operated by the French space agency CNES, with the participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain. All frequency tables, including the identification of combination frequencies, are only available as online material. Frequency Tables are only 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/cgi-bin/qcat?J/A+A/506/471 Bâtiment 121, 91405, Orsay Cedex, France. Postdoctoral Researcher, Fonds de la Recherche Scientifique - FNRS, Belgium. Postdoctoral Fellow of the Fund for Scientific Research, Flanders. [less ▲]

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See detailMOST reveals Spica as an Eclipsing Binary
Desmet, M.; Aerts, C.; Matthews, J. M. et al

in AIP Conference Proceedings (2009, September 01)

We present a unique observational study of Spica, a binary system with a primary component of the β Cephei type. We exploit simultaneous high-resolution spectroscopic observations and high-precision ... [more ▼]

We present a unique observational study of Spica, a binary system with a primary component of the β Cephei type. We exploit simultaneous high-resolution spectroscopic observations and high-precision photometry obtained by the MOST satellite. An important result is that the MOST photometry reveals Spica as an eclipsing binary contrary to what was quoted in the literature. [less ▲]

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See detailFirst asteroseismic results from CoRoT
Michel, Eric; Baglin, A.; Weiss, W. W. et al

in Communications in Asteroseismology (2008), 156

About one year after the end of the first observational run and six months after the first CoRoT data delivery, we comment the data exploitation progress for different types of stars. We consider first ... [more ▼]

About one year after the end of the first observational run and six months after the first CoRoT data delivery, we comment the data exploitation progress for different types of stars. We consider first results to illustrate how these data of unprecedented quality shed a new light on the field of stellar seismology. [less ▲]

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See detailThe Seismology Programme of CoRoT
Michel, Eric; Baglin, A.; Auvergne, M. et al

in Proceedings of "The CoRoT Mission Pre-Launch Status - Stellar Seismology and Planet Finding (2006, November 01)

We introduce the main lines and specificities of the CoRoT Seismology Core Programme. The development and consolidation of this programme has been made in the framework of the CoRoT Seismology Working ... [more ▼]

We introduce the main lines and specificities of the CoRoT Seismology Core Programme. The development and consolidation of this programme has been made in the framework of the CoRoT Seismology Working Group. With a few illustrative examples, we show how CoRoT data will help to address various problems associated with present open questions of stellar structure and evolution. [less ▲]

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See detailThe life of stars and their planets
Catala, C.; Aerts, C.; Aigrain, S. et al

in Favata, F.; Sanz-Forcada, J.; Giménez, A. (Eds.) et al 39TH ESLAB Symposium on Trends in Space Science and Cosmic Vision 2020 (2005, December 01)

We lack a reliable scenario for the formation and evolution of stars and their planetary systems, involving key factors such as magnetic fields and turbulence. We present the case for a mission concept ... [more ▼]

We lack a reliable scenario for the formation and evolution of stars and their planetary systems, involving key factors such as magnetic fields and turbulence. We present the case for a mission concept that will clarify these problems and give us a global view of the evolution of combined star and planetary systems. This will be achieved by simultaneously addressing the search for planetary transits in front of a large number of stars, including many nearby stars, the study of their internal structure and evolution via asteroseismology, and that of their magnetic activity, via UV monitoring. [less ▲]

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See detailAbundance analysis of targets for the COROT/MONS asteroseismology missions. II. Abundance analysis of the COROT main targets
Bruntt, H.; Bikmaev, I. F.; Catala, C. et al

in Astronomy and Astrophysics (2004), 425

One of the goals of the ground-based support program for the COROT and MONS/RÖMER satellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We ... [more ▼]

One of the goals of the ground-based support program for the COROT and MONS/RÖMER satellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential COROT main targets using the semi-automatic software VWA. For two additional COROT targets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the VWA software. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters T[SUB]eff[/SUB], log g, and [Fe/H] to within 70-100 K, 0.1-0.2 dex, and 0.1 dex for five stars which are slow rotators (v sin i < 15 km s[SUP]-1[/SUP]). For most of the stars we find good agreement with the parameters found from line depth ratios, H alpha lines, Strömgren indices, previous spectroscopic studies, and also log g determined from the HIPPARCOS parallaxes. For the fast rotators (v sin i > 60 km s[SUP]-1[/SUP]) it is not possible to constrain the atmospheric parameters. Based on observations obtained with the 193 cm telescope at Observatoire de Haute Provence, France. [less ▲]

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See detailAdditional science potential for COROT
Weiss, W. W.; Aerts, C.; Aigrain, S. et al

in Favata, F.; Aigrain, S.; Wilson, A. (Eds.) Stellar Structure and Habitable Planet Finding (2004, January 01)

Space experiments which are aiming towards asteroseismology and the detection of exoplanets, like COROT or MOST, Eddington and Kepler, are designed to deliver high precision photometric data. Obviously ... [more ▼]

Space experiments which are aiming towards asteroseismology and the detection of exoplanets, like COROT or MOST, Eddington and Kepler, are designed to deliver high precision photometric data. Obviously, they can be used also for other purposes than the primary science goals and in addition many other targets can or will be automatically observed simultaneously with the primary targets. As a consequence, fascinating possibilities for additional (parallel, secondary) science projects emerge. For COROT a dedicated working group was thus established with the goal to contribute any useful information which may optimize the scientific output of the mission. [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 detailThe frequency of Ap-stars with long rotation periods
Hensberge, H.; Manfroid, Jean ULg; Renson, Pierre ULg et al

in Astronomy and Astrophysics (1984), 132

Light variability was observed over time intervals of months to years in the stars HD 55540, HD 71066, HD 94660, and HD 187474. The significance of these results is discussed in terms of the frequency of ... [more ▼]

Light variability was observed over time intervals of months to years in the stars HD 55540, HD 71066, HD 94660, and HD 187474. The significance of these results is discussed in terms of the frequency of chemically peculiar CP2 stars showing (light) variability with periods longer than one month. This frequency, relative to the whole CP2 population, must lie somewhere between 4 and 16 percent. Observations, properly distributed in time, of a small subgroup of CP2 stars will be sufficient to obtain an accurate ratio of the number of LP-CP2 stars to the total number of CP2 stars. These observations, when continued until the periodicity is detected, could contribute also to the discussion whether these long periods should be identified with the rotation period. [less ▲]

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See detailA photoelectric investigation of light variability in Ap stars
Hensberge, H.; Deridder, G.; Doom, C. et al

in Astronomy and Astrophysics. Supplement Series (1981), 46

A study of the light variability of a number of peculiar A stars, mainly in Stromgren colors u and v and in peculiarity index Delta-a, leads to the proposal of the following light variability periods: (1 ... [more ▼]

A study of the light variability of a number of peculiar A stars, mainly in Stromgren colors u and v and in peculiarity index Delta-a, leads to the proposal of the following light variability periods: (1) HD 5601, 1.11 days; (2) HD 19712, 2.19 days; (3) HD 30849, 15.86 days; (4) HD 38823, 8.64 days; (5) HD 53116, 11.98 or 18.10 days; (6) HD 56022, 0.92 days; and (7) HD 81009, 33.97 days. In addition, evidence is given for variability of HD 94660 on a time scale on the order of months or years, and it is shown that the rotation period proposed by Borra and Landstreet (1980) for HD 25267 is not supported by the light variations observed. The character of Delta-a variability is discussed. [less ▲]

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