Microquasars are compact binary stars (a normal very massive star and a compact object), which have an accretion disk around the compact object and an intense and variable radio emission, normally as bipolar jets (symmetric jets of matter in opposite directions). The unusual characteristic of the discovered microquasar in M81 is that the speed of the ejected material is close to the speed of light (that is known as relativistic jets), with a measured velocity of 17% that of light. The main properties of this microquasar all point to a black hole accreting at rates far exceeding the critical rate (there is a theoretical limit to the accretion rate, known as the Eddington limit). This type of black holes “disguise” themselves as supersoft X-ray sources that are normally thought as white dwarfs and the discovery shows observationally what happens if a black hole devours way too much. For this reason the scientists are suggesting this object to be a black hole with supercritical accretion (above the Eddington limit). The possible existence of this type of “superaccreting” black hole had been a source of speculation and research for years, and this result points to a first evidence of its existence.
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It is well known that fullerenes – big, complex, and highly resistant carbon molecules with potential applications in nanotechnology – are mostly seen in planetary nebulae (PNe); old dying stars with progenitor masses similar to our Sun. Fullerenes, like C60 and C70, have been detected in PNe whose infrared (IR) spectra are dominated by broad unidentified IR (UIR) plateau emissions. The identification of the chemical species (structure and composition) responsible for such UIR emission widely present in the Universe is a mystery in astrochemistry; although they are believed to be carbon-rich
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CaII Kgrains, i.e., intermittent, short-lived (about 1 minute), periodic (2-4 minutes), pointlike chromospheric brightenings, are considered to be the manifestations of acoustic waves propagating upward from the solar surface and developing into shocks in the chromosphere. After the simulations of Carlsson and Stein, we know that hot shocked gas moving upward interacting with the downflowing chromospheric gas (falling down after having been displaced upward by a previous shock) nicely reproduces the spectral features of the CaII K profiles observed in such grains, i.e., a narrowband emission
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Red dwarfs are the most common stars in the galaxy. In recent years they have become key targets in the search for exoplanets. These stars are usually accompanied by rocky planets and due to their low brightness, their habitable zone is close to the star, making it easier to find planets that are within it. GJ 1002 is a red dwarf just one-eighth the mass of the Sun, located only 15.8 light-years away. Using radial velocity measurements from the ESPRESSO and CARMENES spectrographs, we have discovered the presence of two Earth-like and potentially habitable planets. The planets, GJ 1002 b and
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