A BOW SHOCK NEAR A YOUNG STAR
NASA's Hubble Space Telescope continues to reveal
various stunning and intricate treasures that
reside within the nearby, intense star-forming
region known as the Great Nebula in Orion. One
such jewel is the bow shock around the very young
star, LL Ori, featured in this Hubble Heritage
Named for the crescent-shaped wave made by a ship
as it moves through water, a bow shock can be
created in space when two streams of gas collide.
LL Ori emits a vigorous solar wind, a stream of
charged particles moving rapidly outward from
the star. Our own Sun has a less energetic version
of this wind that is responsible for auroral displays
on the Earth.
The material in the fast wind from LL Ori collides
with slow-moving gas evaporating away from the
center of the Orion Nebula, which is located to
the lower right in this Heritage image. The surface
where the two winds collide is the crescent-shaped
bow shock seen in the image.
Unlike a water wave made by a ship, this interstellar
bow shock is a three-dimensional structure. The
filamentary emission has a very distinct boundary
on the side facing away from LL Ori, but is diffuse
on the side closest to the star, a characteristic
common to many bow shocks.
A second, fainter bow shock can be seen around
a star near the upper right-hand corner of the
Heritage image. Astronomers have identified numerous
shock fronts in this complex star-forming region
and are using this data to understand the many
complex phenomena associated with the
birth of stars.
This image was taken in February 1995 as part
of the Hubble Orion Nebula mosaic. A nearby neighbor
in our Milky Way galaxy, the nebula is only 1,500
light-years from Earth. The filters used in this
color composite represent oxygen, nitrogen, and
Credit: NASA and the Hubble Heritage Team
Acknowledgment: C. R. O'Dell (Vanderbilt University)