A Burst of Star Formation in the Constellation of Orion
This spectacular panorama of star formation is located about
two degrees south of the Orion Nebula, where a surviving portion
of one of Orion's giant molecular clouds (known as "Orion A")
is continuing to spawn new stars.
Powerful jets of outflowing gas are often the first visible
manifestations of the birth of young stars. These jets punch holes
through the opaque clouds in which the star is formed, holes through
which the light of the new-born stars can escape to produce what
are known as reflection nebulae. Several such nebulae are
seen in this image.
The bright object below and to the left of center is the reflection
nebula NGC 1999, which contains the young star V380 Orionis. A small,
triangle shaped patch of dusty material is seen in silhouette against
the reflection nebula. NGC 1999 lies at the center of a network of
nebulous filaments which billow out and away like the spokes
of a bicycle wheel. These features may trace a wide-angle wind
emerging from NGC 1999.
Near the upper half of the image, bright young stars in a forming
cluster named L1641N light up another reflection nebula which contains
several dense clumps of opaque material. Infrared images have identified
over 50 forming stars in this region. More that six jets and outflows
are erupting from this region.
Outflowing jets from young stars also power luminous shock waves
known as Herbig-Haro (HH) objects, which move through the surrounding
gas as speeds of up to hundreds of kilometers per second (over 100,000
miles an hour). As these shock waves ram their surroundings, they heat up
bow shaped nebulae of glowing plasma. This image shows dozens of such
The region below the NGC 1999 reflection nebula contains a cluster of
deeply embedded young stars which power oppositely directed bow
shocks. These objects were first recognized by Guillermo Haro
and George Herbig around 1950 and today they are known as HH 1 and HH 2.
Recent observations indicate that the cone shape located near the right
edge of the image (known as HH 401) may be a giant bow shock powered by
the source of the HH 1 & 2 outflow. If so, this outflow is more than 10 light
The arc of light which looks like a waterfall (located above and
to the left of HH 401) is the enigmatic object HH 222. Unlike most other HH
objects, it is a source of polarized, non-thermal radio waves. The nature
of this feature remains largely unknown.
Between HH 401 and HH 222 runs a long chain of Herbig-Haro
objects associated with the object HH 34. HH 34 itself is the bright and
compact bow shock located near the bottom of HH 222. Just above HH 34,
a compact jet can be seen to emerge from the source star, which is not
visible in this image. This jet and its first bow shock (HH 34) mark the
inner portion of a chain of shocks which trace a graceful S-shaped curve
from the upper right hand corner of the image down towards HH 1 & 2. The
north end of the flow is just below the top of the image (objects HH 33 & 40); the south end of the flow terminates in a group of small bow shocks known as HH 86 & 87, which reside in the dark region between HH 401 and NGC 1999.
Many other smaller nebulous patches in this image mark small reflection
nebulae, Herbig-Haro objects, and stellar jets. The rich detail in this
image reveals one of the most fascinating areas of the night sky.