Related papers: The pulsating yellow supergiant V810 Centauri
We present spectroscopic abundances and radial velocities for giant stars in the Galactic globular cluster omega Centauri based on the CaII infrared triplet. Two samples of stars were observed: 234 stars at M_V = 1.25 on the lower giant…
We present further photometric observations of the unusual F0 V star 9 Aurigae and present evidence that this star's radial velocity, spectroscopic line widths and line depths are also variable with the same frequencies as the photometric…
Stars pulsating in three radial modes are very rare; only three examples are known in the Galaxy. These stars are very useful since their periods may be measured very precisely, and this will constrain the global stellar parameters and the…
Betelgeuse is a well known bright red supergiant that shows semi-regular variations with four approximate periods of 2200, 420, 230, and 185 days. While the longest period was customarily regarded as LSP (long secondary period) of unknown…
The nature of period and amplitude changes in nonradial pulsators is presently unknown. It is therefore important to examine the correlations between these changes in stars with a large number of simultaneously excited pulsation modes.…
We present a near-infrared J and K photometric catalog containing more than 73,000 stars in the central region of the giant Globular Cluster omega Centauri. This is the largest IR data-set ever published for this cluster and has been used…
We obtained new optical observations of the X-ray source XMMU J083850.38-282756.8, the previously proposed counterpart of the gamma-ray source 3FGL J0838.8-2829. Time-series photometry in the $r'$ band reveals periodic modulation of…
New V-band CCD observations of variable star V2455 Cyg were performed during two nights in September 2017. According to all times of maximum light and new maxima, the O-C curve was analyzed. The period changes of V2455 Cyg were investigated…
Due to their transitionary nature, yellow supergiants provide a critical challenge for evolutionary modeling. Previous studies within M31 and the SMC show that the Geneva evolutionary models do a poor job at predicting the lifetimes of…
The globular cluster Omega Centauri is the most massive and luminous cluster in the Galaxy. The $\gamma$-ray source FL8Y J1326.7$-$4729 is coincident with the core of the cluster, leading to speculation that hitherto unknown radio pulsars…
We present the first extensive seismic modelling of SX Phe stars in the stellar system $\omega$ Cen. First, using the new values of reddening $E(B-V)$ and distance modulus $(m-M)_V$, and bolometric corrections from Kurucz model atmospheres,…
In the first spectroscopic campaign for a PG 1716 variable (or long-period pulsating subdwarf B star), we succeeded in detecting velocity variations due to g-mode pulsations at a level of 1.0-1.5 km/s.The observations were obtained during…
Extensive photometric multisite campaigns of the Delta Scuti variable FG Vir are presented. For the years 2003 and 2004, 926 hours of photometry at the millimag precision level were obtained. The combinations with earlier campaigns lead to…
We present a detailed period analysis of the bright Cepheid-type variable star V1154 Cygni (V =9.1 mag, P~4.9 d) based on almost 600 days of continuous observations by the Kepler space telescope. The data reveal significant cycle-to-cycle…
Recent BRITE-Constellation space photometry of the slowly rotating, magnetic $\beta$ Cep pulsator $\xi^1$ CMa permits a new analysis of its pulsation properties. Analysis of the two-colour BRITE data reveals the well-known single pulsation…
We interpret the stellar population of $\omega$ Centauri by means of a population synthesis analysis, following the most recent observational guidelines for input metallicities, helium and [(C+N+O)/Fe] contents. We deal at the same time…
An understanding of the assembly history of the complex star cluster Omega Centauri has long been sought after, with many studies separating the stars on the color-magnitude diagram into multiple groupings across small magnitude ranges.…
The VVV survey has observed the southern disk of the Milky Way in the near infrared, covering 240 deg$^{2}$ in the $ZYJHK_S$ filters. We search the VVV Survey images in a $\sim$19 deg$^{2}$ field around $\alpha$ Centauri, the nearest…
The analysis of the available TESS light curves of $\alpha$ Sex (HD 87887) reveals low-frequency pulsations with a period of about 9.1 hours in this spectroscopic A0 III standard star. The IUE observations in December 1992 reveal large flux…
Three fields located close to the center of the globular cluster Omega Cen were surveyed in a search for variable stars. We present V-band light curves for 32 periodic variables. This sample includes 10 SX Phe stars, 19 eclipsing binaries,…