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Le osservazioni con MUSE permettono di prevedere la replica irripetibile di una supernova
25 Novembre 2015
Alcuni astronomi hanno utilizzato lo strumento MUSE (Multi Unit Spectroscopic Explorer), installato sul VLT (Very Large Telescope) dell’ESO all’Osservatorio del Paranal, per approfittare di un’opportunità unica e mettere alla prova la capacità di comprendere gli ammassi giganti di galassie. Al momento, stanno facendo la prima previsione in assoluto di un evento di osservazione nell’Universo distante, prima che sia effettivamente visibile.
Immagini dell’ammasso di galassie MACS J1149+2223, ottenute con il telescopio spaziale Hubble della NASA/ESA nel novembre del 2014, hanno svelato una stella lontana in fase di esplosione — una supernova — diversa da tutte quelle vista fino a quel momento. Soprannominata Refsdal [1], è la prima supernova di cui sono state raccolte quattro immagini separate grazie al fenomeno della lente gravitazionale, che ha formato una Croce di Einstein quasi perfetta intorno a una delle galassie dell’ammasso.
La lente gravitazionale è una conseguenza della teoria della relatività generale di Einstein. L’articolo contenente le equazioni che hanno cambiato radicalmente la nostra capacità di comprendere la gravità fu pubblicato il 25 novembre 2015, esattamente un secolo fa.
Le osservazioni cruciali delle distanze precise dalle galassie nella regione di MACS J1149+2223 sono state effettuate usando MUSE all’inizio del 2015 e hanno permesso agli astronomi di modellare la distribuzione della materia all’interno dell’enorme ammasso di galassie con una precisione mai vista prima. Questo ha portato a diverse previsioni su quando e dove apparirà un’altra immagine della lontana supernova — una replica istantanea sullo schermo più grande che si possa immaginare.
Dato che la luce che forma le immagini multiple della supernova percorre traiettorie di unghezza diversa per raggiungere la Terra, le immagini appaiono in tempi diversi e in diversi punti del cielo.
Usando tutti i dati di MUSE disponibili, insieme alle osservazioni di Hubble, un'equipe di astronomi guidata da Claudio Grillo (Dark Cosmology Centre, Istituto Niels Bohr, Università di Copenhagen, Danimarca) ha previsto un’altra replica che raggiungerà la massima luminosità tra marzo e giugno del 2016, con una possibile prima rilevazione entro la fine del 2015. Inoltre, sono stati in grado di prevedere non solo quando e dove la supernova diventerà nuovamente visibile, ma, approssimativamente, anche quanto sarà luminosa.
Attualmente, Hubble viene puntato periodicamente verso l’ammasso, con la speranza di catturare questo evento irripetibile, sottoponendo così i modelli degli astronomi a una prova definitiva.
Queste osservazioni evidenziano il ruolo fondamentale svolto da MUSE e dal VLT nell’esplorazione dell’Universo distante, ma anche la sinergia tra Hubble e gli osservatori da terra.
Note
[1] Prende il nome dal defunto astronomo norvegese Sjur Refsdal, un pioniere nello studio delle lenti gravitazionali.
Links
- Articolo scientifico (Grillo et al)
- Articolo scientifico correlato (Jauzac et al)
- Articolo scientifico correlato (Treu et al)
- Articolo scientifico correlato (Karman et al)
- Annuncio correlato dal telescopio Hubble
Contatti
Claudio Grillo
Dark Cosmology Centre, Niels Bohr Institute
University of Copenhagen, Denmark
Email: grillo@dark-cosmology.dk
Piero Rosati
Department of Physics and Earth Science
University of Ferrara
Email: rosati@fe.infn.it
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
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