We present the analysis of infrared photometry and millimeter spectroscopy of a sample of 74 late-type supergiants. These observations are particularly suitable to study the mass loss and the circumstellar envelopes of evolved massive stars. In particular, we quantify the circumstellar infrared excess, the relation of mass loss with stellar properties, using the K-[12] colour index as mass-loss...

We revisit the scaling relationships between the dark matter mass and observed X– ray luminosity and temperature of galaxy clusters and groups in the local Universe. Specifically, we compare recent observations with analytic models of the intracluster medium in which the gas entropy distribution has been shifted by a variable amount, K◦, to investigate the origin of the scatter in these scaling...

Based on updated nonlinear, convective pulsation models computed for several values of stellar mass, luminosity and metallicity, theoretical constraints on the K−band Period-Luminosity (P L K) relation of RR Lyrae stars are presented. We show that for each given metal content the predicted P L K is marginally dependent on uncertainties of the stellar mass and/or luminosity. Then, by considering...

We revisit the scaling relationships between the dark matter mass and observed X– ray luminosity and temperature of galaxy clusters and groups in the local Universe. Specifically, we compare recent observations with analytic models of the intracluster medium in which the gas entropy distribution has been shifted by a variable amount, K◦, to investigate the origin of the scatter in these scaling...

Context. It has been shown that the luminosity of active galactic nuclei and the size of their broad line region obey a simple relation of the type RBLR = aL, from faint Seyfert nuclei to bright quasars, allowing single-epoch determination of the central black hole mass MBH = bL∆Hβ from their luminosity L and width of Hβ emission line. Adopting this mass determination for cosmological studies r...

Recent investigations on the central stars of planetary nebulae (CSPN) indicate that the masses based on model atmospheres can be much larger than the masses derived from theoretical mass-luminosity relations. Also, the dispersion in the relation between the modified wind momentum and the luminosity depends on the mass spread of the CSPN, and is larger than observed in massive hot stars. Since ...