Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen. The uniformity of their light curves makes these supernovae powerful cosmological distance indicators, but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved. For

We discuss the constraints set on galaxy evolution by a variety of data from deep extragalactic surveys performed in the mid-IR and far-IR with the Infrared Space Observatory and with millimetric telescopes at longer wavelengths. These observations indicate extremely high rates of evolution for IR galaxies, exceeding those measured for galaxies at

Most ultraluminous X-ray sources have a typical set of properties not seen in Galactic stellar-mass black holes. They have luminosities of more than 3 × 1039 ergs per second, unusually soft X-ray components (with a typical temperature of less than about 0.3 kiloelectronvolts) and a characteristic downturn in their spectra above about 5

We report on the discovery of a free-floating methane dwarf toward the direction of the young star cluster σ Ori. Based on the object's far-red, optical, and near-infrared photometry and spectroscopy, we conclude that it is a possible member of this association. We have named it S Ori J053810.1-023626 (S Ori 70 is the abridged name). If it is a

Aims: To show the importance of high-spatial resolution observations of H II regions when compared with observations obtained with larger apertures such as ISO, we present mid-infrared spectra of two Magellanic Cloud H II regions, N88 A and N160 A. Methods: We obtained mid-infrared (8-13 μm), long-slit spectra with TIMMI2 on the ESO 3.6 m telescope

We present a new general procedure for determining a given set of quantities. To this end, we define a certain statistic, which we call `modified χ2' (χ2M), because of its similarity to the standard χ2. The terms of this χ2M are made up of the fluctuations of an unbiased estimator of some statistical quantities and certain weights. Only the