Search Publications

Photometric and Spectroscopic Study of the Delta Scuti Stars FH Cam, CU CVn and CC Lyn

Ogloza, W.; Conidis, G. J.; Gazeas, K. D. +1 more

Three short period (P ∼ 1 day) variable stars from the Hipparcos catalogue targets were observed after suspected misclassification as Beta Lyr eclipsing systems (Perryman et al. 1997), as no secondary component had been noticed in the inspection of their Broadening Functions (BFs) (Rucinski 2002). FH Cam is found to be a multiple star system with …

Photometric observations and frequency analysis of the Delta Scuti star IP UMa

Gavras, P.; Sinachopoulos, D.; Ducourant, Chr.

IP UMa is a Delta Scuti star discovered by Hipparcos. 2642 observations of this target were acquired with the 20cm telescope of the Nea Lesbos Observatory in 10 nights from June 2 to July 9, 2009 using the Bessel V filter. These data confirmed the pulsation frequency of the star listed in the Hipparcos Catalogue (10 c/d).

The true Blazhko behaviour of DM Cyg

Hurta, Zs.

We present preliminary results of our work on DM Cyg, an RRab star with steadily increasing pulsation period. The Blazhko modulation of the light curve of DM Cyg has not been undoubtedly confirmed yet. A reanalysis of the original data (Sódor & Jurcsik 2005) could not confirm the 26 d periodicity found by Lysova & Firmanyuk (1980) in the t…

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…

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…

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.