Low Amplitude New Type Variable Stars in Globular Clusters

Phe stars in globular clusters ?

We present for the first time a catalogue of SX Phetype pulsating variables in globular clusters. In addition, SX Phe variables discovered in the Carina dwarf galaxy and other ones probably belonging to the Sagittarius dwarf galaxy are included. This catalogue is intended to be an up-dated list of all the SX Phe stars, in globular clusters and galaxies, known until now, covering information pub...

Neutron Stars in Globular Clusters

Dynamical interactions that occur between objects in dense stellar systems are particularly important for the question of formation of X-ray binaries. We present results of numerical simulations of 70 globular clusters with different dynamical properties and a total stellar mass of 2 × 107M⊙. We find that in order to retain enough neutron stars to match observations we must assume that NSs can ...

Horizontal Branch A- and B-type Stars in Globular Clusters

Globular clusters offer ideal laboratories to test the predictions of stellar evolution. When doing so with spectroscopic analyses during the 1990s, however, the parameters we derived for hot horizontal branch stars deviated systematically from theoretical predictions. The parameters of cooler, A-type horizontal branch stars, on the other hand, were consistent with evolutionary theories. In 199...

Hot UV bright stars in globular clusters

We have obtained medium-resolution spectra of seven UV-bright stars discovered on images of four southern globular clusters obtained with the Ultraviolet Imaging Telescope (UIT). Effective temperatures, surface gravities and helium abundances are derived from LTE and non-LTE model atmosphere fits. Three of the stars have sdO spectra, including M4Y453 (Teff = 58800 K, log g = 5.15), NGC 6723-III...

Searches for Binary Stars in Globular Clusters