We have developed a numerical code with which we study the effects of 2D perturbations on stellar structure. We present new numerical and analytical results on the heating of a main-sequence star in a binary system by its companion.

Using a statistically representative sample of 911 central galaxies (CENs) from the SDSS DR4 Group Catalogue, we study how the structure (shape and size) of the first rank (by stellar mass) group and cluster members depends on (1) galaxy stellar mass (Mstar), (2) the global environment defined by the dark matter halo mass (Mhalo) of the host group, and (3) the local environment defined by their...

The topology of the magnetic field of young stars is important not only for the investigation of magnetospheric accretion, but also responsible in shaping the large-scale structure of stellar winds, which are crucial for regulating the rotation evolution of stars. Because winds of young stars are believed to have enhanced mass-loss rates compared to those of cool, main-sequence stars, the inter...

Context. The interpretation of stellar pulsations in terms of internal structure depends on the knowledge of the fundamental stellar parameters. Long-base interferometers permit us to determine very accurate stellar radii, which are independent constraints for stellar models that help us to locate the star in the HR diagram. Aims. Using a direct interferometric determination of the angular diam...

We present six simulations of galactic stellar haloes formed by the tidal disruption of accreted dwarf galaxies in a fully cosmological setting. Our model is based on the Aquarius project, a suite of high-resolution N-body simulations of individual dark matter haloes. We tag subsets of particles in these simulations with stellar populations predicted by the GALFORM semianalytic model. Our metho...

The magnetic field structure and the collimated outflow of rapidly rotating Young Stellar Objects (YSOs) are calculated from the stellar source to the asymptotic region. The calculations are based on ideal MHD and the further simplifying assumptions of stationarity and axisymmetry. The star–disk–jet system can be completely defined by the Grad-Shafranov (GSS) equation, describing the structure ...

Superbubbles that result from the stellar winds and supernovae of OB associations probably play a fundamental role in the structure and energetics of the ISM in star-forming galaxies. Their influence may also dominate the relationship between the different interstellar gas phases. How do superbubbles form and evolve? How do they affect the local and global ISM? The Magellanic Clouds provide a s...

If the stellar halos of disk galaxies are built up from the disruption of dwarf galaxies, models predict highly structured variations in the stellar populations within these halos. We test this prediction by studying the ratio of blue horizontal branch stars (BHB stars; more abundant in old, metal-poor populations) to main-sequence turn-off stars (MSTO stars; a feature of all populations) in th...

Strong gravitational lensing and stellar dynamics provide two complementary and orthogonal constraints on the density profiles of galaxies. Based on spherically symmetric, scale-free, mass models, it is shown that the combination of both techniques is powerful in breaking the mass-sheet and mass-anisotropy degeneracies. Second, observational results are presented from the Lenses Structure & Dyn...

A brief summary is presented of our current knowledge of the structure of cold molecular cloud cores that do not contain proto-stars, sometimes known as starless cores. The most centrally condensed starless cores are known as pre-stellar cores. These cores probably represent observationally the initial conditions for protostellar collapse that must be input into all models of star formation. Th...