Category: Ricerca

Supernova explosions produced by LBV stars. The study: “Modeling the remnants of core-collapse supernovae from luminous blue variable stars” of S. Ustamujic (INAF-OAPA) recently appeared on Astronomy & Astrophysics

Ricerca

LBV (Luminous Blue Variable) stars are massive and unstable stars characterized by large mass-lost due to intense stellar winds and aperiodic bursts. Due to their instability, LBV stars are also variable, with quasi-periodic oscillations of their luminosity of the order of 0.5-2 magnitudes. Typical examples of this class of stars are: the supergiant S Doradus in the Large Magellanic Clouds,

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The nature of the binary system NGC1850-BH1 still debated: a system with a 11 solar masses black hole (Saracino et al. 2021) or with a sdOB star (El-Badry et al. 2021)?

Ricerca

In the last years several observational surveys were designed in order to detect stellar mass black holes, including both those which are actively accreting and black holes in a quiescent status. These observations are crucial to understand the real extent of the population of black holes in the Milky Way, and to understand the formation of massive stellar black holes

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Discovered the first planetary system with planets both in equatorial and polar orbits revealed by the study: “The Rossiter-McLaughlin effect revolutions: an ultra-short period planet and a warm mini-Neptune on perpendicular orbits” of V. Bourrier (Observatoire Astronomique de l’Université de Genève), appeared on A&A

Ricerca

The study of the architecture of planetary systems, and in particular that of the spin-orbit angle (which is the inclination of the planetary orbit with respect to the stellar rotation axis) can unveil important details on the dynamical evolution of planetary systems. In particular, young planets typically migrate radially, changing their distance to the host star and interacting with the

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The properties of the exoplanets sculpted by the forming environment. The study: “Exploring the link between star and planet formation with Ariel” of D. Turrini (INAF-IAPS) appeared on Experimental Astronomy

Ricerca

To date (October 2021, data from https://exoplanets.nasa.gov/), astronomer discovered enough exoplanets (in excess of 4500) to allow not only analysis of individual planets, but also detailed studies of the whole exoplanets population. These studies are necessary to fully understand the process of planets formation, the evolution of planets, the chemical composition and physical properties of planets atmospheres, and how the forming

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The study: “Estimating Magnetic Filling Factors from Simultaneous Spectroscopy and Photometry: Disentangling Spots, Plage, and Network” of T. W. Milbourne (Harvard University), recently appeared on ApJ, present two new methods that allow astronomers to estimate the filling factor of magnetic active regions

Ricerca

About 20% of the exoplanets discovered so far (October 2021) were found with measurements of radial velocity (data from https://exoplanets.nasa.gov/). This method is based on spectroscopic observations of stars with planets, from which it is possible to measure the Doppler effect produced by periodic oscillations of the star, due to the gravitational attraction between star and planet along the orbit of

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Published in A&A the paper describing the catalog of the candidate targets for the PLATO mission: “The all-sky PLATO input catalogue” of M. Montalto (Unipd/INAF-OAPd)

Ricerca

According to the data released by NASA, to date (2021 October 1st) we have confirmed 4525 exoplanets in 3357 planetary systems. The vast majority of these planets (75%) were discovered with the methods of transits, while about 20% with that of radial velocity. With the former technique, planets are discovered when they transit in front of their stars along our line

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The hot Jupiter WASP-33b targeted by HARPS-N. The study: “The GAPS Programme at TNG. XXXI. The WASP-33 system revisited with HARPS-N” of F. Borsa (INAF – AO of Brera) recently appeared on A&A

Ricerca

Hot Jupiters are gaseous giant planets that orbit very close to their stars (within a typical distance of less than 0.1 Astronomical Units, AU, where 1 AU is the average distance between Earth and Sun, about 150 million of km). These planets are of great interest for astronomers both because of the effects due to the intense incident stellar radiation,

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Cepheids and X-ray emission. The study “X-rays in Cepheids: XMM-Newton Observations of η Aql” of N. R. Evans (SAO-CfA) recently appeared on AJ

Ricerca

Cepheids are stars of great importance, since they allow to determine the distance of galaxies within a few hundreds of million of light years from us. This is due to the pulsations that characterize these giant stars, which are going through an instable phase of their evolution. Because of these pulsations, the luminosity of these stars varies with a period

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Lithium abundance and stellar internal structure. The study: “The Gaia-ESO survey: Mixing processes in low-mass stars traced by lithium abundance in cluster and field stars” of L. Magrini (INAF – OA Arcetri) recently appeared on A&A

Ricerca

The chemical history of Lithium abundance in the Universe is very complex. This chemical element has been first produced during the Big Bang, even if in very small quantities compared with hydrogen and helium. Since then, lithium is continuously created and destroyed by several processes occurring in stellar interior. This means that the lithium abundances we observe in stars today

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There is no relation between age and metallicity of the stars in the Solar neighbourhood. The study: “Constraining the solar neighbourhood age-metallicity relation from white dwarf-main sequence binaries” of A. Rebassa-Mansergas (Universitat Politècnica de Catalunya) recently appeared on MNRAS

Ricerca

After the Big Bang, the Universe contained only hydrogen, helium, and a very small fraction of lithium. After that, stars, mainly the most massive ones, were responsible for the chemical enrichment of the Universe. In fact, stars produce energy by synthetizing chemical elements in their cores. These elements are then redistributed in the interstellar medium when stars end their evolution.

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