Using high-quality H_α images of five spiral galaxies, we have studied the luminosity and distribution of the emission from diffuse ionized gas (DIG). The...

To test recent suggestions that the infrared emission of low-luminosity AGN arises in a truncated thin accretion disk, we compare recent, high-resolution IR...

As part of a systematic effort to characterize the properties and progenitors of the most luminous planetary nebulae (PNe), we obtained a sample among the...

The Planetary Nebulae Luminosity Function (PNLF) is an important standard candle on the extragalactic distance ladder. Its use is based on the empirical...

In order to better estimate the earth climatic variations at scales corresponding to decennia or centuries it appears more and more important to understand the...

Modern cosmology has sharpened questions posed for millennia about the origin of our cosmic habitat. The age-old questions have been transformed into two...

Fossil groups (FGs) are galaxy systems with masses and X-ray haloes comparable to to those of groups and clusters of galaxies, but whose optical light is...

The planetary nebulae (PNe) of M 31 are receiving considerable attention as probes of its structure and chemical evolution in a galactic environment that is...

On the basis of astrometric and spectroscopic data we argue that the ultramassive white dwarf GD 50 is associated with the star formation event that created the...