Hidden behind a shroud of dust in the constellation Cygnus is a
stellar nursery called DR21, which is giving birth to some of the most
massive stars in our galaxy. Visible light images reveal no trace of this
interstellar cauldron because of heavy dust obscuration. In fact, visible
light is attenuated in DR21 by a factor of more than
10,000,000,000,000,000,000,000,000,000,000,000,000,000 (ten thousand
trillion heptillion).
New images from NASA's Spitzer Space Telescope allow us to peek behind
the cosmic veil and pinpoint one of the most massive natal stars yet seen
in our Milky Way galaxy. The never-before-seen star is 100,000 times as
bright as the Sun. Also revealed for the first time is a powerful outflow
of hot gas emanating from this star and bursting through a giant
molecular cloud.
This image is a large-scale mosaic assembled from individual
photographs obtained with the InfraRed Array Camera (IRAC) aboard
Spitzer. The image covers an area about two times that of a full moon.
The mosaic is a composite of images obtained at mid-infrared wavelengths
of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8
microns (red). The brightest infrared cloud near the top center
corresponds to DR21, which presumably contains a cluster of newly forming
stars at a distance of 10,000 light-years.
Protruding out from DR21 toward the bottom left of the image is a
gaseous outflow (green), containing both carbon monoxide and molecular
hydrogen. Data from the Spitzer spectrograph, which breaks light into
its constituent individual wavelengths, indicate the presence of hot
steam formed as the outflow heats the surrounding molecular gas. Outflows
are physical signatures of processes that create supersonic beams, or
jets, of gas. They are usually accompanied by discs of material around
the new star, which likely contain the materials from which future
planetary systems are formed. Additional newborn stars, depicted in
green, can be seen surrounding the DR21 region.
The red filaments stretching across this image denote the presence of
polycyclic aromatic hydrocarbons. These organic molecules, comprised of
carbon and hydrogen, are excited by surrounding interstellar radiation
and become luminescent at wavelengths near 8.0 microns. The complex
pattern of filaments is caused by an intricate combination of radiation
pressure, gravity and magnetic fields. The result is a tapestry in which
winds, outflows and turbulence move and shape the interstellar medium.
To the lower left of the mosaic is a large bubble of gas and dust,
which may represent the remnants of a past generation of stars.
