Download guide to orion 3-d flythrough

GUIDE TO ORION 3-D FLYTHROUGH
0:00-0:10
The flythrough begins directly below the nebula and moves northward toward its center. The
nebula is carved out of a giant, dark cloud of molecular gas and dust and is painted on the cloud’s
surface by the intense radiation from its brightest star. The direction to Earth is straight up. The
dark cloud at the top is the veil that obscures part of the nebula when viewed from Earth.
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The central area of the nebula is called the Trapezium cluster. It is dominated by four young,
massive stars in a kite-like arrangement. The brightest of these stars, which has a luminosity
100,000 times that of the Sun, provides the energy that creates the nebula as we see it. It
produces a flood of ultraviolet light that ionizes the surface layers of the molecular cloud and
causes them to glow. This illumination makes it possible to study many features that otherwise
would be invisible.
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These bright stars are extremely young, less than 100,000 years old. That means our distant
ancestors were alive when the nebula came into being.
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The nebula’s irregular surface is caused by the intense starlight. The radiation not only causes
the gases in the cloud to glow, but it also eats away at the material in the cloud, forming ridges
and valleys.
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Circling the Trapezium cluster, we travel underneath the foreground veil. The Earth-side of the
cloud is dark, but the inner side, which faces the Trapezium, is painted in glowing colors.
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As we loop inward toward the heart of the nebula, our course takes us through the opaque veil.
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The fuzzy, teardrop-shaped objects are clouds of dust and gas that contain newly formed stars.
The teardrop shape is an artifact of the strong illumination. Actually, the clouds surrounding the
young stars are nearly spherical. New stars are created when knots of dust and gas collapse. In
the nebula, however, this process stopped when the young central stars reached their full power.
The radiation they produce is so strong that it prevents new stars from forming.
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A young star with a proto-planetary disk passes by. Ninety percent of the newly formed stars in
the cluster possess such disks. The object, named HST10, is also the best example of a dynamic
phase in stellar creation: the formation of strong, bipolar jets that blast twin streams of dust and
gas away from the star at hypersonic velocities.
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GUIDE TO ORION 3-D FLYTHROUGH
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In the nebula today, the starlight is so intense that it can blast away the material in a protoplanetary disk in a few hundred thousand years. By comparison, scientists think that it takes 10
million years for a planet to form. So nine out of ten of the new stars formed in Orion are unlikely
to develop planetary systems.
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As we pull back from the Trapezium, two young stars still shrouded by the cloud of dust and gas
pass by. Because they are farther from the central stars, they appear to be more nearly spherical.
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Our path takes us above the foreground veil as we circle around for a final pass of the Trapezium.
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From this angle the shockwaves produced by the jets streaming from young, forming stars are
clearly visible as translucent crescents. Those that face the central star are shaped by interaction
with a wind of gas coming from the stars along with the starlight. Those with other orientations
form by the interaction between the jets and the gas left over from star formation.
2:15-2:30
Finally, while we continue to face the center of the nebula, our trajectory curves upward until we
are traveling at a right angle to our previous course and heading in the direction of Earth. As we
move farther and farther away, the familiar outline of the nebula as seen from Earth falls into
place.
Produced by the American Museum of Natural History under the direction of Carter Emmart.
Computer visualization by Jon D. Genetti, David R. Nadeau and Erik Wesselak at the San Diego Supercomputer
Center.
Based on the nebula model provided by C. Robert O’Dell of Vanderbilt University and Zheng Wen, formerly of
Rice University, and a stellar cluster model from Lynne Hillenbrand of California Institute of Technology and Lee
Hartmann of the Center for Astrophysics.
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