The azimuthal power spectra of optical emission from star formation and dust in spiral galaxies resembles the azimuthal power spectra of HI emission from the LMC. These and other power spectra of whole galaxies all resemble that of velocity in incompressible Kolmogorov turbulence. The reasons for this are unknown but it could be simply that star and cloud formation are the result of a mixture o...

The first detections of afterglows from short gamma-ray bursts (GRBs) have confirmed the previous suspicion that they are triggered by a different central engine than long bursts. In particular, the recent detections of short GRBs in galaxies without star formation lends support to the idea that an old stellar population is involved. Most prominent are mergers of either double neutron stars or ...

We perform a seismic study of the young massive β Cephei star HD 203664 with the goal to constrain its interior structure. Our study is based on a time series of 328 new Geneva 7-colour photometric data of the star spread over 496.8 days. The data confirm the frequency of the dominant mode of the star which we refine to f1 = 6.02885 c d. The mode has a large amplitude of 37 mmag in V and is una...

We compute the luminosity function (LF) and the formation rate of long gamma ray bursts (GRBs) by fitting the observed differential peak flux distribution obtained by the BATSE satellite in three different scenarios: i) GRBs follow the cosmic star formation and their LF is constant in time; ii) GRBs follow the cosmic star formation but the LF varies with redshift; iii) GRBs form preferentially ...

We investigate the multi-wavelength properties of a sample of 450-μm selected sources from the SCUBA-2 Cosmology Legacy Survey (S2CLS). A total of 69 sources were identified above 4σ in deep SCUBA-2 450-μm observations overlapping the UDS and COSMOS fields and covering 210 arcmin to a typical depth of σ450 = 1.5mJy. Reliable cross identification are found for 58 sources (84 per cent) in Spitzer...

We discuss the serendipitous discovery of an extremely metal poor galaxy, SDSS 0809+1729, classified as a star in the Sloan Digital Sky Survey (SDSS). The galaxy has a redshift z = 0.0441 and a B-band absolute magnitude MB = −17.1. With a metallicity of log(O/H) + 12∼ 7.44 or ∼ 1/20 solar, this galaxy is among the 10 most metal poor emission-line galaxies known. SDSS 0809+1729 is a blue compact...