Search Publications

Solar-like oscillations in red giants in the CoRoT exofield

De Ridder, J.; Barban, C.; Hekker, S. +4 more

Asteroseismic observations from space can provide us with long time series of uninterrupted high quality data for many stars at the same time. The CoRoT satellite (Convection Rota- tion and planetary Transits) was launched successfully in December 2006 and provides high precision photometery for a large number of stars. Here we present our researc…

Analysing the Hipparcos epoch photometry of λ Bootis stars

Paunzen, E.; Reegen, P.

We performed a homogeneous analysis of the available Hipparcos epoch photometry for all members of the LB group. Besides the known δ Scuti like pulsation frequencies, we searched for eclipses due to binarity or rotational induced variability. The already known frequencies of HD 15165 are confirmed with an additional lower single frequency, which m…

Solar-like stars as seen by CoRoT

Auvergne, M.; Baudin, F.; Michel, E. +7 more

For more than a year, photometric high-quality data have been achieved from the CoRoT (COnvection ROtation and Planetary Transits; Baglin et al. 2006, Michel et al. 2008) min- isatellite developed by the French space agency (CNES) in collaboration with the Science Program of ESA, Austria, Belgium, Brazil Germany and Spain. The power spectrum of 4 …

Extracting oscillation frequencies from sparse spectra: Fourier analysis

Jerzykiewicz, M.

I begin by explaining the properties of spectral windows of time-series data. Emphasis is on data obtained at a single geographic longitude, but ground-based multi-longitude cam- paigns and space missions such as MOST and Hipparcos are not entirely neglected. In the second section, I consider the Fourier transform of time-series data and the proce…

CoRoT data contribution to stellar seismology

Auvergne, M.; Baudin, F.; Michel, E. +2 more

At the time to submit papers for these proceedings, CoRoT will be launched in less than one month. The scientific programme, the instrument and the mission profile have been described in several places recently (e.g., Baglin et al. 2006, Michel et al. 2006a) and a dedicated volume (Fridlund et al. 2006) has been published, where these aspects are …

Photometric observations and frequency analysis of the δ Scuti NT Hya

Gavras, P.; Sinachopoulos, D.

NT Hya is a δ Scuti star discovered by Hipparcos. About 2200 observations were acquired with the 30 inch SAAO telescope in the nights of February 2,3 and 4, 2006 in V filter. These data show four pulsation frequencies of the star. Two of them may form a doublet separated by 0.64 c/d (Δf/f = 9%) with similar amplitudes. The period listed in the Hip…

New variable and multiple stars in the lower part of the Cepheid instability strip

Lampens, P.; Fremat, Y.; van Cauteren, P. +1 more

We obtained high-resolution spectra for 33 A-type stars during 4 consecutive nights. All our targets are Hipparcos program stars located in the lower part of the Cepheid instability strip which show hints for variability in radial velocity of a yet unidentified nature. CCD photometry was acquired for some of the most promising candidates and used …

Short-Period Variables in ASAS Photometry

Molenda-Zakowicz, J.

We present results of our study of short--period variables in ASAS photometry. We focus on slowly pulsating B stars (SPBs), most of which were discovered by the Hipparcos satellite. We discuss the problem of aliasing in the ASAS photometry and its influence on the identification of frequencies of SPBs. Finally, we show that the ASAS photometry can…

Is TU UMi a W UMa-type system

Amado, P. J.; Olivares, I.; Rolland, A. +4 more

TU UMi is catalogued as a delta Scuti star, it was discovered by Hipparcos (ESA 1997). Analysis of photometric observations carried through the years 2001 and 2002 is presented. We obtain one only frequency that it is in agreement with it listed in the Hipparcos Catalogue. Using the derived uvbybeta indices, the most relevant physical parameters o…

Fishing for Delta Scuti stars in the Hipparcos photometric database

Percy, J. R.; Gilmour-Taylor, G.