Il pianeta più estremo mai visto è un gigante gassoso che raggiunge una temperatura di 3'200 gradi perché orbita molto vicino a una stella così calda da apparire blu. Distante 322 anni luce, il pianeta si chiama Wasp-189b ed è stato scoperto dalla missione Cheops, dell'Agenzia spaziale europea (ESA). Un progetto a cui partecipa anche la Svzzera.
Il risultato è stato pubblicato sulla rivista Astronomy & Astrophysics dal gruppo dell'università di Ginevra coordinato da Monika Lendl. Gli strumenti della sonda hanno misurato la variazione di luminosità del sistema durante il transito del pianeta sul disco della stella, permettendo di stimare anche la temperatura superficiale di Wasp-189 b.
Il pianeta, che si trova nella costellazione della Bilancia, orbita attorno alla stella HD 133112, una delle più calde finora note per avere un sistema planetario. Il raggio di Wasp-189 b è quasi 1,6 volte il raggio di Giove e la sua temperatura rovente porta il ferro sciogliersi e a diventare gassoso.
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