L’abbondanza di elementi chimici pesanti nelle regioni di formazione stellare influenza l’evoluzione delle stelle e dei loro dischi protoplanetari? Nuovi indizi da uno studio sulla regione Sh2-284 Nei primi milioni di anni di vita, le giovani stelle sono spesso circondate da un disco di gas e polveri chiamato “disco protoplanetario”. Come suggerisce il nome, è la struttura da cui
Scoperta di due esopianeti attorno alla stella “povera di metalli” TOI-5788 Grazie all’analisi dei dati ottenuti dai satelliti TESS (NASA) e CHEOPS (ESA), insieme allo spettrografo HARPS-N del Telescopio Nazionale Galileo, un team di ricercatori guidato dall’astrofisico B. S. Lakeland (Università di Birmingham ed Exeter) ha scoperto e caratterizzato due esopianeti in orbita attorno a TOI-5788, una stella di
As of today (February 2025), out of the 5834 identified exoplanets, only about 5% orbit stars with masses between 1.5 and 3.5 solar masses (intermediate-mass stars). This is likely due to specific difficulties in exoplanet detection techniques, difficulties that are not encountered for lower-mass stars. For example, since they are more luminous than lower-mass stars, the transit depth (i.e., the
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.
The mechanisms involved in the formation of planets are still not completely understood. The most widely accepted model that describe the formation of gaseous planets is the core-accretion model. In this paradigm, the formation of these planets starts with the formation of a large rocky core by the coagulation of planetesimals, followed by the accretion of a large gaseous envelope
To date, about 4000 exoplanets (planets orbiting around other stars) have been confirmed. Stars hosting planets and sub-stellar companions span a wide range of stellar parameters and even evolutionary phases. For this reason, several studies have been focused on the connection between stellar parameters and the possibility to host planets or sub-stellar companions such as brown dwarfs. In particular,
