Uma estrela supergigante única
A Fotografia da Semana de hoje faz-nos lembrar aquelas imagens 3D que precisam daqueles óculos de papel com filtros vermelhos e verdes para poderem ser vistas corretamente. Na realidade, esta imagem mostra uma estrela supergigante vermelha no final da sua vida, a expelir uma enorme quantidade de gás e poeira. Estas nebulosas observam-se frequentemente em torno de estrelas supergigantes, no entanto, esta, em particular, apresenta-se como um mistério algo inesperado para os astrónomos.
Trata-se da maior nuvem de material ejetado alguma vez encontrada em torno de uma estrela supergigante, apresentando a enorme dimensão de 1,4 anos-luz. Os astrónomos estudaram esta estrela, Stephenson 2 DFK 52, com o auxílio do Atacama Large Millimeter/submillimeter Array (ALMA), ao mesmo tempo que outras supergigantes nas suas proximidades. A DFK 52 é bastante semelhante a Betelgeuse, outra supergigante vermelha famosa, por isso esperava-se encontrar uma nuvem semelhante em torno dela. No entanto, se a DFK 52 estivesse tão perto de nós como a Betelgeuse, a nuvem de gás e poeira que a rodeia ver-se-ia no céu com um tamanho equivalente a um terço da Lua Cheia.
Estas novas observações do ALMA permitiram aos astrónomos medir a quantidade de matéria que rodeia a estrela e a velocidade a que esta matéria se desloca. As zonas da nebulosa que se movem na nossa direção estão destacadas a azul e as que se afastam de nós estão a vermelho. Os dados mostram que há cerca de 4000 anos esta estrela sofreu uma perda extrema de massa, mas posteriormente essa perda abrandou para a sua taxa atual, mais semelhante à taxa de perda de massa da Betelgeuse. Estima-se que a DFK 52 tenha 10 a 15 vezes mais massa do que o Sol e que, até agora, tenha perdido já entre 5 e 10% da sua massa inicial.
É ainda um mistério para os cientistas como é que esta estrela conseguiu expelir tanto material em tão pouco tempo. Ter-se-á tratado de alguma interação estranha com uma estrela companheira? Por que é que a forma da nuvem é deveras complexa? Existirão mais supergigantes como esta? Descobrir o porquê da enorme perda de massa da DFK 52 ajudará os astrónomos a compreender melhor como é que esta estrela terminará a sua vida sob a forma de uma explosão de supernova algures nos próximos milhões de anos.
Link
Créditos:ALMA(ESO/NAOJ/NRAO)/M. Siebert et al.
Sobre a imagem
| Id: | potw2531a |
| Língua: | pt |
| Tipo: | Observação |
| Data de divulgação: | 4 de Agosto de 2025 às 06:00 |
| Tamanho: | 2704 x 2644 px |
Sobre o objeto
| Nome: | Stephenson 2 DFK 52 |
| Tipo: | Milky Way : Star : Evolutionary Stage : Red Supergiant Milky Way : Star : Circumstellar Material Milky Way : Nebula |
Formatos de imagens
Papéis de parede
Cores e filtros
| Banda | Telescópio |
|---|---|
| Milímetro CO (blueshifted) | Atacama Large Millimeter/submillimeter Array Band 6 |
| Milímetro CO (redshifted) | Atacama Large Millimeter/submillimeter Array Band 6 |
| Milímetro Continuum | Atacama Large Millimeter/submillimeter Array Band 6 |
| Milímetro CO (rest frame) | Atacama Large Millimeter/submillimeter Array Band 6 |
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