We demonstrate the eclipsing binary detection performance of the Gaia variability analysis and processing pipeline using Hipparcos data. The automated pipeline classifies 1,067 (0.9%) of the 118,204 Hipparcos sources as eclipsing binary candidates. T
he detection rate amounts to 89% (732 sources) in a subset of 819 visually confirmed eclipsing binaries, with the period correctly identified for 80% of them, and double or half periods obtained in 6% of the cases.
We summarize the properties of the new periodic, small amplitude, variable stars recently discovered in the open cluster NGC 3766. They are located in the region of the Hertzsprung-Russell diagram between delta Sct and slowly pulsating B stars, a reg
ion where no sustained pulsation is predicted by standard models. The origin of their periodic variability is currently unknown. We also discuss how the Gaia mission, to be launched at the end of 2013, can contribute to our knowledge of those stars.
The ESA Gaia mission will bring a new era to the domain of standard candles. Progresses in this domain will be achieved thanks to unprecedented astrometric precision, whole-sky coverage and the combination of photometric, spectrophotometric and spect
roscopic measurements. The fundamental outcome of the mission will be the Gaia catalogue produced by the Gaia Data Analysis and Processing Consortium (DPAC), which will contain a variable source classification and specific properties for stars of specific variability types. We review what will be produced for Cepheids, RR Lyrae, Long Period Variable stars and eclipsing binaries.
Starting from a few topical astrophysical questions which require the knowledge of the age of Pop I stars, we discuss the needed precision on the age in order to make progresses in these areas of research. Then we review the effects of various inputs
of the stellar models on the age determination and try to identify those affecting the most the lifetimes of stars.
The X-ray spectra of Low Mass X-ray Binaries (LMXB) can change on short time-scales, making it difficult to follow their spectral characteristics in detail through model fitting. Colour-colour (C-C) diagrams are therefore often used as alternative, m
odel independent, tools to study the spectral variability of these sources. The INTEGRAL mission, with its high sensitivity, large field of view and good angular resolution, is well suited to study the hard X-ray properties of LMXBs. In particular the ISGRI imager on board of INTEGRAL allows the regular monitoring of the sources in the less frequently studied domain above 20 keV. In this proceeding, C-C diagrams have been made with data from the INTEGRAL public archive; a search is made for systematic differences in the C-C diagrams between black hole candidates (BH) and neutron stars (NS) in LMXBs using a moments analysis method.
