Una spirale celeste con un colpo di scena
Malgrado assomigli al disegno di una conchiglia sulla spiaggia, quest’intrigante spirale è nella realtà di natura astronomica. ALMA (Atacama Large Millimeter/submillimeter Array) ha catturato questa notevole immagine di una stella binaria, dove le due stelle - LL Pegasi e la sua compagna, si intrecciano in una danza cosmica, orbitando attorno al loro centro di massa comune. La stella più vecchia LL Pegasi perde in continuazione materiale gassoso, mentre evolve in una nebulosa planetaria, e la netta forma a spirale è l’impronta lasciata dalle stelle orbitando in questo gas.
La spirale si estende su anni-luce e si avvolge con un straordinaria regolarità. In base al tasso di espansione del gas nella spirale, gli astronomi stimano che un nuovo “strato” appaia ogni 800 anni - approssimativamente lo stesso tempo che le due stelle impiegano per percorrere un’orbita completa una attorno all’altra.
LL Pegasi è stata prima evidenziata circa 10 anni fa quando il telescopio spaziale Hubble della NASA e ESA ha catturato l’immagine di questa struttura quasi perfetta. Era una delle prime volte che si scopriva una struttura a spirale nel materiale circostante di una stella vecchia. Ora le osservazioni di ALMA, di cui quest’immagine è solo una sezione trasversale, hanno aggiunto una dimensione in più per svelare una squisita geometria 3D della struttura a spirale. Una vista completa 3D è disponibile in questo video.
Un’ulteriore immagine mostra una combinazione di dati di ALMA e di Hubble.
Link
Crediti:
ALMA (ESO/NAOJ/NRAO)/H. Kim et al.
A proposito dell'immagine
| Identificazione: | potw1710a |
| Lingua: | it |
| Tipo: | Osservazione |
| Data di pubblicazione: | Lunedì 06 Marzo 2017 06:00 |
| Dimensione: | 996 x 997 px |
A proposito delll'oggetto
| Nome: | LL Pegasi |
| Tipo: | Milky Way : Star : Grouping : Binary |
| Constellation: | Pegasus |
Formati delle immagini
Coordinate
| Position (RA): | 23 19 12.61 |
| Position (Dec): | 17° 11' 33.07" |
| Field of view: | 0.32 x 0.32 arcminutes |
| Orientazione: | Il Nord è a -0.0° a sinistra della verticale |
Colori e filtri
| Banda | Telescopio |
|---|---|
| Millimetrico 13CO | Atacama Large Millimeter/submillimeter Array Band 6 |
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