| 11. Nov 2009 @ 08:56 (bez virsraksta) |
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The Birth of StarsThe spectacular new camera installed on
NASA's Hubble Space Telescope during Servicing Mission 4 in May has
delivered the most detailed view of star birth in the graceful, curving
arms of the nearby spiral galaxy M83.
Nicknamed the Southern
Pinwheel, M83 is undergoing more rapid star formation than our own
Milky Way galaxy, especially in its nucleus. The sharp 'eye' of the
Wide Field Camera 3 (WFC3) has captured hundreds of young star
clusters, ancient swarms of globular star clusters, and hundreds of
thousands of individual stars, mostly blue supergiants and red
supergiants.
WFC3's broad wavelength range, from ultraviolet to
near-infrared, reveals stars at different stages of evolution, allowing
astronomers to dissect the galaxy's star-formation history.
The
image reveals in unprecedented detail the current rapid rate of star
birth in this famous "grand design" spiral galaxy. The newest
generations of stars are forming largely in clusters on the edges of
the dark dust lanes, the backbone of the spiral arms. These fledgling
stars, only a few million years old, are bursting out of their dusty
cocoons and producing bubbles of reddish glowing hydrogen gas.
The excavated regions give a colorful "Swiss cheese" appearance to the
spiral arm. Gradually, the young stars' fierce winds (streams of
charged particles) blow away the gas, revealing bright blue star
clusters. These stars are about 1 million to 10 million years old. The
older populations of stars are not as blue.
A bar of stars,
gas, and dust slicing across the core of the galaxy may be instigating
most of the star birth in the galaxy's core. The bar funnels material
to the galaxy's center, where the most active star formation is taking
place. The brightest star clusters reside along an arc near the core.
The remains of about 60 supernova blasts, the deaths of massive stars,
can be seen in the image, five times more than known previously in this
region. WFC3 identified the remnants of exploded stars. By studying
these remnants, astronomers can better understand the nature of the
progenitor stars, which are responsible for the creation and dispersal
of most of the galaxy's heavy elements.
M83, located in the
Southern Hemisphere, is often compared to M51, dubbed the Whirlpool
galaxy, in the Northern Hemisphere. Located 15 million light-years away
in the constellation Hydra, M83 is two times closer to Earth than M51.
Image
Credit: NASA, ESA, R. O'Connell (University of Virginia), B. Whitmore
(Space Telescope Science Institute), M. Dopita (Australian National
University), and the Wide Field Camera 3 Science Oversight Committee
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