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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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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H II regions are ionized nebulae associated with the formation of massive stars. They exhibit a wealth of emission lines in their spectra that form the basis for estimation of chemical composition. The amount of heavy chemical elements is essential to the understanding of important phenomena such as nucleosynthesis, star formation and chemical evolution of galaxies. For over 80 years, however, a discrepancy exists of a factor of around two between heavy-element abundances (the so-called metallicity) derived from the two main kinds of emission lines that can be measured in nebular spectra
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In the 90s, the COBE satellite discovered that not all the microwave emission from our Galaxy behaved as expected. Part of this signal was later assigned to a fresh new emission component, spatially correlated with the Galactic dust emission, which showed greater importance in the microwave range of frequencies. It has been named since as “anomalous microwave emission”, or AME. The current main hypothesis to explain the AME origin is that it is emitted by small dust particles which undergo fast spinning movements. In Fernández-Torreiro et al. (2023), we study the observational properties of
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