Category: Ricerca

The magnetic field in SN1987A revealed from radio observations. The study: “Polarized radio emission unveils the structure of the pre-supernova circumstellar magnetic field and the radio emission in SN1987A” of O. Petruk (INAF-OAPA) appeared on A&A

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Without any doubts, the supernova remnants SN1987A is the one that taught us more about this class of objects and supernova exposions. Produced by a supernova exploded in the Large Magellanic Cloud on February 23rd 1987, this is the only case in which we have observations of the progenitor, of the supernova explosion, and in which we follow the development

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The binary fraction in Cepheids revealed by X-ray observations. The paper: “X-Rays in Cepheids: Identifying Low-mass Companions of Intermediate-mass Stars” of N. R. Evans (SAO) recently appeared on ApJ

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Cepheids are important stars for the well-known relation between the period of their pulsations and their intrinsic luminosities. These stars are in fact characterized by regular pulsations whose period increases linearly with their absolute magnitude. Cepheids have a mass of about 5 solar masses, thus their progenitors are B stars in Main Sequence. However, their evolutionary path can be affected

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A joint study Solar Orbiter / Parker Solar Probe of the solar wind. The paper: “Connecting Solar Orbiter remote-sensing observations and Parker Solar Probe in situ measurements with a numerical MHD reconstruction of the Parker spiral” of R. Biondo (UNIPA/INAF-OATo) recently appeared on A&A

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Solar wind is made of charged particles (plasma) ejected by the coronal magnetic activity and travelling through the interplanetary space. Once these particles reach Earth and interact with the magnetosphere and atmosphere of our planet, they produce phenomena such as the aurorae.   In their journey through the interplanetary space, these particles are funelled by the solar magnetic field. Every

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Different regimes of particle acceleration in supernova remnants. The study: “A Spatially Resolved Study of Hard X-Ray Emission in Kepler’s Supernova Remnant: Indications of Different Regimes of Particle Acceleration” of V. Sapienza (UNIPA/OAPA) appeared on ApJ

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Cosmic rays are high-energy charged particles which continuously hit our planet. These particles are accelerated up to such high velocities in different astronomical environments, among which supernova remnants seems to be particularly important. These objects are nebulae in rapid expansion generated by the explosions of very massive stars. In supernova remnants, particle acceleration seems to occurr along the expanding shock

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Two bright flares in DS Tuc A and their impact on the nearby planet. The paper: “X-ray flares of the young planet host Ds Tucanae A” of I. Pillitteri recently appeared on A&A

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Flares are among the most energetic magnetic phenomena occuring in stars. They are triggered by a sudden release of energy previously stored in the stellar magnetic field, and then they culminate with the formation of magnetic loops in the stellar coronae filled by X-ray and UV emitting plasma at million degrees. Sometimes, these magnetic structures erupt, releasing in the surrounding

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Thermal inversion in the atmosphere of Hot Jupiters. The study: “The GAPS Programme at TNG. XXXIII. HARPS-N detects multiple atomic species in emission from the dayside of KELT-20b” of F. Borsa (INAF – OA Brera) recently appeared on A&A

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Thermal inversion is a common phenomenon on Earth’s atmosphere. It occurs when temperature does stop decreasing with increasing height, typically because of layers of warm air flowing upon cold air close to the ground. On Earth, this phenomenon plays an important role in the formation of clouds and precipitation.   Thermal inversion is important also for a peculiar class of

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Howe many planets around M dwarf stars? The study: “HADES RV Programme with HARPS-N at TNG. XV. Planetary occurrence rates around early-M dwarfs” of M. Pinamonti (INAF-OATo) recently appeared on A&A

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M dwarf stars, with temperature ranging between 2400 and 3900 K and mass between 0.08 and 0.7 solar masses, are ideal targets for the search of exoplanets. This because the most important techniques to search for exoplanets are more effective when applied to stars of this spectral type than to more massive stars. For instance, the method of radial velocity

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The properties of the reverse shock in Cas A reveal properties of the progenitor. The paper: “Evidence for past interaction with an asymmetric circumstellar shell in the young SNR Cassiopeia A” of S. Orlando (INAF – OAPA) recently appeared on A&A

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Supernova remnants (expanding clouds produced by the explosion of massive stars) are fascinating objects. Their study, in fact, can unveil the physical processes working during supernova explosions and even the properties of the stellar progenitors. To these aims, of particular importance is the analysis of the physical and chemical properties of the ejecta (which are the fragments of the dying

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Stellar age and magnetic activity. The study: “The GAPS programme at TNG XXXIV. Activity-rotation, flux–flux relationships, and active-region evolution through stellar age” of J. Maldonado (INAF-OAPA) recently appeared on A&A

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Almost all stars in the Universe produce their own magnetic field with a process called stellar dynamo, whose basic ingredients are stellar rotation and convection. In general, magnetic fields are produced and are affected by charged particles, which is what stellar plasma is made of. In stars the magnetic field and plasma thus interact, producing a class of transient phenomena

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A chapter wrote by M. Barbera, U. Lo Cicero and L. Sciortino (INAF-OAPA) on the filters for X-ray telescopes is included in the: “Handbook of X-ray and gamma ray astrophysics”

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X-ray astronomy explores the high-energy Universe. X-rays are, in fact, high energy photons emitted by very hot gas (with temperature of some milion degrees) or by processes involving relativistic particles. Some astronomical sources of X-rays radiation are: accreting black holes, such as the supermassive black holes at the center of active galaxies, stellar coronae, supernova remnants, and clusters of galaxies.

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