We report early follow-up observations of the error box of the short burst GRB 050813 using the telescopes at Calar Alto and Observatorio Sierra Nevada, followed by deep VLT FORS2 I-band observations obtained under very good seeing conditions 5.7 and 11.7 days after the event. Neither a fading afterglow nor a rising SN component was found, so the

A search is performed for anomalous interactions of the recently discovered Higgs boson using matrix element techniques with the information from its decay to four leptons and from associated Higgs boson production with two quark jets in either vector boson fusion or associated production with a vector boson. The data were recorded by the CMS

Patat et al. recently inferred the existence of circumstellar material around a normal Type Ia supernova (SN Ia) for the first time, finding time-variable Na I D absorption lines in the spectrum of SN 2006X. We present high-resolution spectroscopy of the bright SN Ia 2007af at three epochs and search for variability in any of the Na D absorption

We study the disc emission component hidden in the single-peaked broad emission lines (BELs) of active galactic nuclei. We compare the observed broad lines from a sample of 90 Seyfert 1 spectra taken from the Sloan Digital Sky Survey with simulated line profiles. We consider a two-component broad line region model where an accretion disc and a

Star formation rates (SFRs) of galaxies are commonly calculated by converting the measured Hα luminosities (LHα) into current SFRs. This conversion is based on a constant initial mass function (IMF) independent of the total SFR. As was recently recognized, the maximum stellar mass in a star cluster is limited by the embedded total cluster mass and

Results of coordinated observations of the flare star EV Lac in September 1992 are presented. Among 25 flares detected during 28 hours on patrol in Crimea four had large enough amplitudes to permit the quantitative analysis of their radiation by colour-colour diagrams. Calculation of V-I colour index for different radiation sources enable us to