Related papers: Is \lambda\ Cep a pulsating star?
EE Cep is an eclipsing binary with a period of 5.6 years. The next eclipse will occur soon, in May-June 2003, and all available past eclipses were collected and briefly analysed. EE Cep shows very large changes of the shape and the depth of…
Context. RU Lup is a Classical T Tauri star with unusually strong emission lines, which has been interpreted as manifestations of accretion. Recently, evidence has accumulated that this star might have a variable radial velocity. Aims. We…
XZ Ceti is the only known anomalous Cepheid in the Galactic field. Being the nearest and brightest such variable star, a detailed study of XZ Ceti may shed light on the behaviour of anomalous Cepheids whose representatives have been mostly…
We report a multisite photometric campaign for the Beta Cep stars V2052 Oph and V986 Oph. 670 hours of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with eight telescopes on five…
Hybrid stars like Nu Eridani and 12 Lacertae show two different types of pulsations: (i) low-order acoustic and gravity modes of the Beta Cephei type with periods of about 3-6 hours, and (ii) high-order gravity modes of the SPB type with…
We undertook a multisite photometric campaign for the Beta Cephei star Nu Eridani. More than 600 hours of differential photoelectric uvyV photometry were obtained with 11 telescopes during 148 clear nights. The frequency analysis of our…
We have studied the photometric variability of ten SMC Be/X-ray pulsars using MACHO and OGLE-II data. For some of these systems we have found periodic behavior, including orbital outbursts and/or nonradial pulsations (NRP) of the Be star.…
We report the discovery of large-amplitude, periodic X-ray emission from the O7 V star theta^1 Orionis C, the central star of the Orion Nebula. Ten ROSAT HRI snapshots of the Trapezium cluster taken over the course of 21 days show that the…
We present three years of long-cadence and over one year of short-cadence photometry of the central star of the Planetary Nebula NGC 6826 obtained with the Kepler spacecraft, and temporally coinciding optical spectroscopy. The light curves…
Investigating period changes of classical Cepheids through the framework of $O-C$ diagrams provides a unique insight to the evolution and nature of these variable stars. In this work, the new or extended $O-C$ diagrams for 148 Galactic…
We present results of the radial velocity (RV) analysis of spectroscopic time-series observations of the roAp star HD24712 (HR1217) which were carried out simultaneously with the Canadian MOST mini-satellite photometry. Only lines of the…
We report the latest set of spectropolarimetric observations of the magnetic $\beta$ Cep star $\xi^1$ CMa. The new observations confirm the long-period model of Shultz et al.\ (2017), who proposed a rotational period of about 30 years and…
Magnetic chemically peculiar (mCP) stars of the upper part of the main sequence usually exhibit strictly periodic variations of their light, spectrum and magnetic field. These changes can be well explained using the oblique rotator model of…
In addition to coherent pulsation, many accreting neutron stars exhibit flaring activity and strong aperiodic variability on time scales similar to or shorter than their pulsation period. Such a behavior shows that the accretion flow in the…
We present the first short time scale observations of the roAp star gamma Equ in linear polarized light obtained with the PEPSI polarimeter installed at the LBT. These observations are used to search for pulsation variability in Stokes Q…
Studies based on high-resolution spectroscopic data of rapidly oscillating Ap stars show a surprising diversity of pulsation behavior in the atmospheric layers, pointing, in particular, to the co-existence of running and standing waves. The…
Short-period high-amplitude pulsating stars of Population I ($\delta$ Sct stars) and II (SX Phe variables) exist in the lower part of the classical (Cepheid) instability strip. Most of them have very simple pulsational behaviours, only one…
We present detailed analysis of the vertical pulsation mode cross-section in ten rapidly oscillating Ap (roAp) stars based on spectroscopic time-series observations. The aim of this analysis is to derive from observations a complete picture…
$\beta$ Cephei pulsating variable (BCEP) stars are the most massive pulsating variable stars in the main sequence, exhibiting both p- and g-mode pulsations. In this study, we identified 155 BCEP stars or candidates using data from TESS and…
I review recent results of the observations of magnetoacoustic p-mode oscillations in roAp stars with the focus on time-resolved spectroscopic studies. Time-series spectroscopy of roAp stars reveals unexpected and diverse pulsational…