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FOR RELEASE: January 22, 1997

PHOTO NO.: STScI-PRC96-38a


GIANT "TWISTERS" AND STAR WISPS IN THE LAGOON NEBULA

This NASA Hubble Space Telescope (HST) image reveals a pair of one-half
light-year long interstellar "twisters" -- eerie funnels and twisted-rope
structures (upper left) -- in the heart of the Lagoon Nebula (Messier 8)
which lies 5,000 light-years away in the direction of the constellation
Sagittarius.

The central hot O type star, Herschel 36 (upper left in photo), is the
primary source of the ionizing radiation for the brightest region in
the nebula, called the Hourglass. Other hot stars, also present in the
nebula, are ionizing the extended optical nebulosity. The ionizing
radiation induces photo-evaporation of the surfaces of the clouds (seen
as a blue "mist" at the right of the image), and drives away violent
stellar winds tearing into the cool clouds.

Analogous to the spectacular phenomena of Earth tornadoes, the large
difference in temperature between the hot surface and cold interior of the
clouds, combined with the pressure of starlight, may produce strong
horizontal shear to twist the clouds into their tornado-like appearance.
Though the spiral shapes suggest the clouds are "twisting", future
observations will be needed, perhaps with Hubble's next generation
instruments, with the spectroscopic capabilities of the Space Telescope
Imaging Spectrograph (STIS) or the Near Infrared Camera and Multi-Object
Spectrometer (NICMOS), to actually measure velocities.

This Hubble picture reveals a variety of small scale structures in the
interstellar medium, small dark clouds called Bok globules, bow shocks around
stars, ionized wisps, rings, knots and jets.


The Lagoon Nebula and nebulae in other galaxies are sites where new stars are
being born from dusty molecular clouds. These regions are the "space
laboratories" for the astronomers to study how stars form and the interactions
between the winds from stars and the gas nearby. By studying the wealth of
data revealed by HST, astronomers will understand better how stars form in the
nebulae.

These color-coded images are the combination of individual exposures taken in
July and September, 1995 with Hubble's Wide Field and Planetary Camera 2
(WFPC2) through three narrow-band filters (red light -- ionized sulphur atoms,
blue light -- double ionized oxygen atoms, green light -- ionized hydrogen).

This work is based on public data retrieved from the HST Archive, cosmic-ray
cleaned, calibrated and combined by Adeline Caulet (Space Telescope European
Coordinating Facility, European Space Agency).

Credit: A. Caulet (ST-ECF, ESA) and NASA

Image files in GIF and JPEG format and captions may be accessed on the
Internet via anonymous ftp from oposite.stsci.edu in /pubinfo.

GIF JPEG
PRC96-38a Lagoon Nebula gif/m8wide.gif jpeg/m8wide.jpg

Higher resolution digital versions (300 dpi JPEG) of the release photograph
are available in /pubinfo/hrtemp: 96-38a.jpg and 96-38b.jpg (color) and
96-38abw.jpg and 96-38bbw.jpg (black/white).

GIF and JPEG images, captions and press release text are available via World
Wide Web at
http://www.stsci.edu/pubinfo/PR/96/38.html and via links in:
http://www.stsci.edu/pubinfo/Latest.html or
http://www.stsci.edu/pubinfo/Pictures.html.