(Section Not Complete)
The image adjacent right shows starbirth regions in the
Eagle Nebula (M16), which is about 7000 light years away in the
The yellow rectangle in the inset indicates the region of the nebula blown up in the main part of
Here is a Hubble Space Telescope
(780 kB MPEG)
or equivalently a
streaming animation (1.1 MB)
of these star forming regions. This
illustrates the location of these star forming regions in the sky.
The clouds are
columns of cool molecular hydrogen and dust that that serve as
incubators for new stars. The tallest is almost a light year in length!
The finger-like protrusions at the top of the clouds are larger than the
solar system and hide embryonic stars that are forming within them.
The pillars are
being eroding away by photoevaporation caused by
the ultraviolet light from nearby hot stars (approximately 100 young stars can be counted in
this part of the nebula).
This evaporation uncovers small globules of dense gas buried within the cloud
that are termed EGGs ("Evaporating Gaseous Globules").
The finger-like structures at the top of the clouds are produced
by the shadows of the EGGs, which protect the gas behind them from the intense UV flux.
The image adjacent left shows a region of star birth in the Triffid Nebula, which is approximately
9000 light years away in the constellation Sagittarius
(Ref). There is a hot, young star above and to the right
of this image. When it formed, its radiation and stellar wind swept away much of the gas in this region
and only low-mass stars are presently forming here.
The pillars visible in the image were more dense than their surroundings and thus have survived, though
they too are being eroded by the radiation and wind from hot stars. The unusual jet of material that can
be seen in the upper left is not well understood, though its source presumably lies hidden in the large
left pillar. The red dots are newly formed low-mass stars.
The adjacent IR image from the 8.2 meter telescope of the
European Southern Observatory
shows a very young open cluster in which
the stars are still immersed in the dust from which they were born.
This cluster, which is designated RCW38 is about 5000 light years away in the
When we see most open clusters
we don't see so much dust because the stars have had time to move away from the nebula in which they
formed and to disperse the dust with radiation pressure. In this case the stars are so young that they
are still hiding in the dust. In visible light they would be mostly obscured by the dust, but
IR penetrates the dust much better and allows the open cluster to be imaged
Time to Collapse
to the Main Sequence
(Millions of Years)
In the preceding figure, most of the stars lying to the right appear to still
be collapsing to the main sequence.
As young stars form, there often still remains substantial accreting matter around them. The new young
star has strong solar winds associated with its just-born fusion reactions and matter trying to
onto the star is thought to be heated and ejected in jets along the axis of rotation. As
this ejected material slams into the gas in the interstellar medium it tends to form nebulosity
at the ends of the oppositely directed jets. The following image
(Ref) shows a Hubble Space Telescope
observation of such a situation in the vicinity of the Orion Nebula
Such bright patches of nebulosity moving away from protostars and very young stars are
called Herbig-Haro Objects. In the above image the young star responsible for the jets
and the nebulae at either end of the jets
is thought to be hidden in the dark dust cloud in the center of the image. The entire width of this image
is about 1 light year.
The following Hubble Space Telescope image shows another jet from a young star
Designated HH-47, this 3 trillion mile long
jet originates from a star hidden in a dust cloud near the left edge of the image.
The twisted nature of the jet suggests that the star emitting it is wobbling on its rotation axis, perhaps
because of interaction with another star. The Herbig-Haro object HH-47 is about 1500 light years away,
lying at the edge of the Gum Nebula, which is possibly an ancient supernova remnant.
Catalog of Herbig-Haro objects