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| Space twister? This is not a dance or a game, but perhaps a never-before
seen structure in a nebula
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| Like most other nebulae, the Lagoon Nebula
contains clouds of cold molecular Hydrogen that are being
ionized by a powerful nearby star. In this case the star,
O Herschel 36 (seen in the upper left part of the picture above, and in the detail to the right),
is boiling away the outer layers of the nebula. This "photoevaporation" is
causing the blue "haze" around some of the clouds as the heated gas
flows away from the cool interior. The same process is responsible for
the appearance of the Eagle Nebula.
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Another interesting feature of the nebula is Bok globules. These
small dark spots are dusty clouds in the initial stages of
collapse. Like the globules in the Orion Nebula, they may one day
turn into stars.
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| But the Lagoon Nebula reveals an entirely new phemomenon:
Giant structures that resemble tornadoes on Earth. They
may be caused by the interaction of the cold core with the hot surface
of the gas cloud, and radiation pressure from the star. A star's light
is so powerful that its pressure can push clouds of gas.
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| But
to know whether these objects really are three dimensional "twisters"
we will need to know the velocity of the gas at various points in the
clouds. Astronomers will be better able to get this information with
the new instruments going into Hubble in the second servicing mission,
scheduled for February 11 1997. Two new instruments, the Near Infrared
Camera and Multi-Object Spectrometer (NICMOS) and the Space Telescope
Imaging Spectrograph (STIS) will both be capable of making spectral
observations that can provide velocites of the gas in the clouds.
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| These images of the Lagoon Nebula were created by
Adeline Caulet of the
Space Telescope
European Coordinating Facility.
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The Lagoon Nebula
Detail of the Lagoon Nebula
