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
Our planet is constantly bombarded by energetic particles (mainly protons) called “cosmic rays“. The study of cosmic rays is a leading science topic given its importance in several fields, such as the study of the effects on instrumentation and astronauts in space, where the natural protection against these particles provided by the magnetic field of Earth is low or null.
The amount of gas that is converted into stars by the star formation process is described by the star formation rate. For instance, in the Milky Way today between 0.7 and 1.5 solar masses of gas are converted into stars each year. However, this a mean value across our Galaxy, since locally clouds can start forming stars at higher rates
On June 2019, the panel for the evaluation of the proposals for observations with the NASA telescope Chandra, operating in the X-rays, which met up in Boston, has approved the Large Project: “Star formation in starburst: a deep ACIS-I observation of Westerlund 1“, led by the astronomer Mario Giuseppe Guarcello – INAF Astronomical Observatory of Palermo. More details on the
Stellar X-ray emission arises from their corona, which is the outer part of stellar atmosphere with low-density high-temperature (up to million degrees) plasma. Even if we lack a fully understanding of the details, we know that the intensity of stellar X-ray emission depends on the intensity and the morphology of stellar magnetic field. The interior of stars of FGK
Most of the stars, mainly the low mass stars, produce their own magnetic field in their interior. The interaction between the magnetic field and stellar plasma is the cause of phenomena such as photosperic spots, faculae, protuberances, coronal mass ejections, and flares. The study of this activity is important both because it reveals how intense magnetic fields interact with high-temperature
OB associations are objects of great importance, since they contain a rich population of OB stars. Despite their paucity, OB stars have a strong impact on the evolution of their parental clouds, nearby stars, and the whole Galaxy. For instance, their intense UV emission affects the evolution of the parental cloud and the star formation process in it, sometimes triggering
What remains after a supernova explosion, which is among the most energetic phenomena in the Universe, is an expanding cloud interacting with the surrounding interstellar medium (the “supernova remnants”) and a compact object produced by the contraction of the nucleus of the progenitor star. Given its proximity to the Sun (“only” 945 light years), the Vela supernova remnant is one
di Mario Giuseppe Guarcello ( segui mguarce) È stato pubblicato sul sito del satellite Chandra della NASA un articolo (link) interamente dedicato agli studi INAF-OAPA/CfA della regione di formazione stellare nota come Nebulosa dell’Aquila o M16, contenente l’ammasso stellare NGC 6611, realizzato con vari telescopi operativi in diverse bande dello spettro elettromagnetico, tra cui il satellite Chandra della
During their short existence lasting only few million years, massive stars (more massive than 8 solar masses with spectral type O and B-early) strongly affect the surrounding environment thanks to their intense UV radiation and stellar winds. A single O star, in fact, can loose about 10-6 solar masses of gas in a wind reaching velocities of 1600–2500 km s−1 (Stevens & Hartwell, 2003).
