 THE
HEART OF THE TRIFID NEBULA
The Trifid Nebula, cataloged by astronomers as
Messier 20 or NGC 6514, is a well-known region of
star formation lying within our own Milky Way Galaxy.
It is called the Trifid because the nebula is overlain
by three bands of obscuring interstellar dust, giving
it a trisected appearance as seen in small telescopes.
The Trifid lies about 9,000 light-years (2,700 parsecs)
from Earth, in the direction of the constellation
Sagittarius.
This new image from the Hubble Space Telescope
offers a close-up view of the center of the Trifid
Nebula, near the intersection of the dust bands,
where a group of recently formed, massive, bright
stars is easily visible. These stars, which astronomers
classify as belonging to the hottest and bluest
types of stars called type "O," are releasing
a flood of ultraviolet radiation that dramatically
influences the structure and evolution of the surrounding
nebula. Many astronomers studying nebulae like the
Trifid are focusing their research on the ways that
waves of star formation move through such regions.
The group of bright O-type stars at the center
of the Trifid illuminates a dense pillar of gas
and dust, seen to the right of the center of the
image, producing a bright rim on the side facing
the stars. At the upper left tip of this pillar,
there is a complex filamentary structure. This wispy
structure has a bluish color because it is made
up of glowing oxygen gas that is evaporating into
space. Star formation is no longer occurring in
the immediate vicinity of the conspicuous group
of bright O-type stars, because their intense radiation
has blown away the gas and dust from which stars
are made.
The Hubble image of the Trifid Nebula has given
astronomers insight into the nature of the interaction
of gaseous, dusty and stellar material in an area
where dust, gas clouds, and new and old stars coexist.
The science team, composed of Farhad Yusef-Zadeh
(Northwestern U.), John Biretta (STScI), Bob O'Dell
(Vanderbilt U.), and Mark Wardle (Macquarie U.),
took exposures in filters that transmit light emitted
by oxygen, hydrogen, and sulfur ions. The images
were taken with the Wide Field Planetary Camera
2 onboard Hubble in mid-summer 2001 and 2002. This
image was produced by the Hubble Heritage Team.
Image Credit: NASA, ESA, and The Hubble Heritage
Team (AURA/STScI) Acknowledgment: F. Yusef-Zadeh
(Northwestern Univ.) |
