Dark matter is a type of material which has not been observed through any telescope, but whose existence is deduced from its gravitational effects on visible matter. In 1974 the astronomer Vera Rubin measured the rotation curves of the stars in orbit around the centres of spiral galaxies and noticed that at distances greater than a certain radial distance from the nucleus the stars rotate at virtually constant velocity, independently of their distance from the  centre of rotation. However the estimates of the mass of the visible matter, the stars and the gas in the galaxy lead to predictions

The Earth’s albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured from space platforms, but also from the ground for sixteen years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim is of quantifying sustained monthly, annual and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change

We present deep imaging observations of activated asteroid P/2016 G1 (PANSTARRS) using the 10.4m Gran Telescopio Canarias ( GTC)  from 2016 late April to early June.  Activated asteroids are objects in orbits typical of asteroids with unlike origin in the cometary reservoirs (the Oort Cloud or the trans-neptunian belt), that ejected dust by any mechanism: sublimation of volatiles (like comets do); collision with another asteroid or rotational disruption. The images of P/2016 G1 show a dust cometary-like coma and were analysed by comparing them with simulated images obtained using a computed

We present new medium-resolution spectroscopic observations of the black hole X-ray binary Nova Muscae 1991 taken with X-Shooter spectrograph installed at the 8.2-m VLT telescope. These observations allow us to measure the time of inferior conjunction of the secondary star with the black hole in this system that, together with previous measurements, yield an orbital period decay of (dP/dt)= −20.7±12.7 ms yr −1 (−24.5 ± 15.1 μs per orbital cycle). This is significantly faster than those previously measured in the other black hole X-ray binaries A0620-00 and XTE J1118+480. No standard black

In some AGN, nuclear dust lanes connected to kpc-scale dust structures provide all the extinction required to obscure the nucleus, challenging the role of the dusty torus proposed by the Unified Model. In this letter we show the pc-scale dust and ionized gas maps of Circinus constructed using sub-arcsec-accuracy registration of infrared VLT AO images with optical Hubble Space Telescope images. We find that the collimation of the ionized gas does not require a torus but is caused by the distribution of dust lanes of the host galaxy on ~10 pc scales. This finding questions the presumed torus

During the last decades, growing evidence about the presence of planetary material around white dwarfs has been established. The features of heavy elements in the spectra of a large fraction (25-50%) of these objects needs a frequent accretion of material orbiting close to the white dwarf. Additionally, at least 4% of these objects are known to host dusty disks. The space mission K2, that re-uses the Kepler instrument after a failure of two of its four gyroscopes, recently detected transiting material around WD1145+017, with periods in the 4.5-5h range, and a depth variability with scales of