Il sogno "senza speranza" di Einstein è stato realizzato: per la prima volta è stato possibile determinare la massa di una stella studiando il modo in cui la sua forza di gravità curva lo spazio circostante, deviando il cammino della luce proveniente da un'altra stella posta sullo sfondo ma non perfettamente allineata.
Lo studio, pubblicato sulla rivista Science, si basa sui dati del telescopio spaziale Hubble, di Nasa e Agenzia spaziale europea (ESA), analizzati da un gruppo internazionale di astronomi. Oltre a confermare ancora una volta la validità della relatività generale, il risultato rappresenta una prima assoluta e nei prossimi anni aiuterà a misurare la massa di molti altri oggetti celesti altrimenti impossibili da "pesare".
A fare da apripista, in questo studio, è stata la stella Stein 2051 B, che ha rivelato una massa pari al 68% di quella del nostro Sole. Si tratta di una nana bianca, ovvero una stella allo stadio finale della sua evoluzione che ha bruciato tutto il "carburante": comprendere meglio le sue caratteristiche sarà fondamentale per ricostruire la storia e prevede il futuro della Via Lattea, dove il 97% delle stelle sono o diventeranno nane bianche.
ATS/Swing
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