- Original Caption Released with Image:
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IRA-MIPS Composite
Visible
IRAC
MIPS
The LMC is a small satellite galaxy gravitationally bound to our own
Milky Way. Yet the gravitational effects are tearing the companion to
shreds in a long-playing drama of 'intergalactic cannibalism.' These
disruptions lead to a recurring cycle of star birth and star death.
Astronomers are particularly interested in the LMC because its fractional
content of heavy metals is two to five times lower than is seen in our
solar neighborhood. [In this context, 'heavy elements' refer to those
elements not present in the primordial universe. Such elements as carbon,
oxygen and others are produced by nucleosynthesis and are ejected into
the interstellar medium via mass loss by stars, including supernova
explosions.] As such, the LMC provides a nearby cosmic laboratory that
may resemble the distant universe in its chemical composition.
The primary Spitzer image, showing the wispy filamentary structure of
Henize 206, is a four-color composite mosaic created by combining data
from an infrared array camera (IRAC) at near-infrared wavelengths and
the mid-infrared data from a multiband imaging photometer (MIPS). Blue
represents invisible infrared light at wavelengths of 3.6 and 4.5
microns. Note that most of the stars in the field of view radiate
primarily at these short infrared wavelengths. Cyan denotes emission
at 5.8 microns, green depicts the 8.0 micron light, and red is used to
trace the thermal emission from dust at 24 microns. The separate
instrument images are included as insets to the main composite.
An inclined ring of emission dominates the central and upper regions of
the image. This delineates a bubble of hot, x-ray emitting gas that was
blown into space when a massive star died in a supernova explosion
millions of years ago. The shock waves from that explosion impacted a
cloud of nearby hydrogen gas, compressed it, and started a new generation
of star formation. The death of one star led to the birth of many new
stars. This is particularly evident in the MIPS inset, where the
24-micron emission peaks correspond to newly formed stars. The
ultraviolet and visible-light photons from the new stars are absorbed
by surrounding dust and re-radiated at longer infrared wavelengths,
where it is detected by Spitzer.
This emission nebula was cataloged by Karl Henize (HEN-eyes) while
spending 1948-1951 in South Africa doing research for his Ph.D.
dissertation at the University of Michigan. Henize later became a
NASA astronaut and, at age 59, became the oldest rookie to fly on the
Space Shuttle during an eight-day flight of the Challenger in 1985. He
died just short of his 67th birthday in 1993 while attempting to climb
the north face of Mount Everest, the world's highest peak.
- Image Credit:
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NASA/JPL-Caltech
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