We investigate the validity of the core mass – luminosity relation (CMLR), originally described by Paczyński (1970), for asymptotic giant branch stars under the presence of third dredge-up events. We find, that models with efficient third dredge-up with less massive cores than those associated with hot bottom burning (Blöcker and Schönberner, 1991) do not obey the linear CMLR. Complete evolutio...

For spiral galaxies, the active galactic nucleus (AGN) and some physical parameters that concern host galaxy such as arm radius density can play an important role in morphological evolution of these galaxies. Considering gravitational effect central black hole a feeding mechanism, gas flows from arms to accretion disk. Accordingly, we constructed our approach derived equation for AGN luminosity...

New black-hole mass estimates are presented for a sample of 72 AGN covering three decades in optical luminosity. Using a sub-sample of Seyfert galaxies, which have blackhole mass estimates from both reverberation mapping and stellar velocity dispersions, we investigate the geometry of the AGN broad-line region (BLR). It is demonstrated that a model in which the orbits of the line-emitting mater...

Recent work has demonstrated that there is a tight correlation between the mass of a black hole and the velocity dispersion of the bulge of its host galaxy. We show that the model of Kauffmann & Haehnelt, in which bulges and supermassive black holes both form during major mergers, produces a correlation between Mbh and σ with slope and scatter comparable to the observed relation. In the model, ...

The abundance of galaxy clusters as a function of mass is determined using the 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) catalogue. This is used to estimate the amplitude of the matter fluctuation spectrum, parametrised by the linear theory rms density fluctuations in spheres of 8h Mpc, σ8. The best-fitting value for this parameter is highly correlated with the mean matter density in the...

Modern instrumentation makes it possible to measure the mass to radius ratio for main sequence stars in open clusters from gravitational redshifts. For stars where independent information is available for either the mass or the radius, this application of general relativity directly determines the other quantity. Applicable examples are: 1) measuring the radii of solar metallicity main sequence...

Massive Black Holes detected by in the centers of many nearby galaxies show an approximately linear relation with the luminosity of the host bulge, inferring the black hole has a mass of 0.001-0.002 of the bulge. Previous work suggested that black holes of active (Seyfert 1) galaxies follow a similar relation, but apparently with a significantly lower value of MBH/Mbulge (Wandel 1999). New data...

Metal-poor globular clusters (GCs) are our local link to the earliest epochs of star formation and galaxy building. Studies of extragalactic GC systems using deep, high-quality imaging have revealed a small but significant slope to the color-magnitude relation for metal-poor GCs in a number of galaxies. We present a study of the M87 GC system using deep, archival HST/ACS imaging with the F606W ...

We have obtained adaptive optics images and accurate radial velocities for 7 very low mass objects, In the course of a long term effort to determine accurate masses for very low mass stars (M<0.6 M). We use the new data, together with measurements from the litterature for some stars, to determine new or improved orbits for these 7 systems. They provide masses for 16 very low mass stars with acc...