O Vz stars are defined as those O-type stars displaying He II 4686 absorption line stronger than other He line in the blue spectral region. These stars have been hypothesized on spectroscopic grounds to be O-type stars on or close to the Zero-Age-Main-Sequence (ZAMS), also having weaker winds than normal O V stars. We have tested these hypothesis

We revisit the paradigm of the dependence of jet power on black hole (BH) spin in accreting BH systems. In a previous paper, we showed that the luminosity of compact jets continuously launched due to accretion on to BHs in X-ray binaries (analogous to those that dominate the kinetic feedback from active galactic nuclei) does not appear to correlate

X-ray transients (XTs) provide some of the strongest evidence for the existence of stellar mass black holes (BHs). In these systems, X-ray outbursts occur over timescales of weeks to months and are followed by years of quiescence when the optical light from the system is dominated by the companion star. Successful programs for determining the orbit

As part of a systematic search programme of a 10° wide strip of the northern Galactic plane, we present preliminary evidence for the discovery of four (and possibly five) new supernova remnants (SNRs). The pilot search area covered the 19-20 h right ascension zone sampling from +20° to +55° in declination using binned mosaic images from the Isaac

NEFER (Nuevo Espectrómetro Fabry-Pérot de Extrema Resolución) is a 3D instrument aimed to implement high resolution spectrometry for velocity determinations of extended stellar objects.

This communication presents a prototype image slicer for the 4-m European Solar Telescope (EST) designed for the spectrograph of the 1.5-m GREGOR solar telescope (GRIS). The design of this integral field unit has been called MuSICa (Multi-Slit Image slicer based on collimator-Camera). It is a telecentric system developed specifically for the