Astronomy Picture of the Day

Thor's Helmet in H-Alpha

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#84132 by @ 03.02.2006 00:00 - nach oben -
Thor's Helmet in H-Alpha


Near picture center, the helmet-shaped structure with
wing-like appendages is popularly called
Thor's Helmet.

Cataloged as NGC 2359, the striking nebula is located about
15,000 light-years away in the constellation

The helmet is actually more like
cosmic bubble
, blown as the
wind from the bright, massive star near the bubble's center sweeps
through the surrounding molecular cloud.

Known as a
Wolf-Rayet star, the energetic star is a blue giant
thought to be in a brief,
pre-supernova stage of evolution.

The remarkable color composite
combines broad and narrow band images -
including a deep exposure recorded with an
H-alpha filter.

The H-alpha image traces the light from
the region's glowing atomic hydrogen gas.

Heroically sized even for a
Norse god,
this Thor's Helmet is about 30 light-years across.

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