Sunday, June 5, 2011
(Check out the Galactic Rose -- a beautiful configuration of colliding galaxies -- over at www.timothyhallinan.com/blog.)
What we have above is the whole star cycle: birth, youth, old age, and death. It's Galactic Emissions Nebula NGC 3603. A Galactic Emissions Nebula is one that has been identified by its "noise" -- extremely strong emissions of radiation. Astronomers scan vast swaths of sky with radio telescopes and then point the Hubble at the noisiest areas. Once in a while, they see something like this.
A "nebula" just means something shapeless, apparently disorganized, and sometimes fuzzy. The word was first used prior to the installation of the Hale Telescope at Mount Palomar to describe what looked like pale patches of stars. Seen through a stronger instrument, they turned out to be galaxies. Millions and millions of them.
Today, the word is used to describe something like NGC 3606. It's shapeless to the untrained eye because most of it is just gigantic clouds of glowing gas. It's "noisy," in terms of radiation, because enormous transformations, both creative and destructive, are taking place there.
The dark areas so unspectacularly surrounding the nebula are "Bok globules" -- relatively cold, relatively dense areas of hydrogen and helium that have not yet achieved enough gravity to begin to spin and then collapse into stars. At one point in cosmic history -- back before there was light in the universe -- Bok globules were the densest aggregations of matter. In a sense, they're stars-in-waiting.
The bright clouds of gas and the brighter pillars they contain are nurseries. They're lighted up by the ignition of brand new stars, Bok globules that have been squeezed by gravity until a thermonuclear reaction took place and they began to shine. There are millions of them inside those yellowish clouds.
The brilliant blue objects in the middle are maturing stars of considerable size and brilliance. They're visible because their "solar wind" -- a nonstop flow of protons, electrons, and photons that can weigh billions of tons lost each hour -- has literally blown the gas of the clouds away. So there they shine, pristine in the empty space they've cleared for themselves. They may or may not have young planets or proto-planets around them at this stage in their development.
The ultra-bright star with the glowing circle around it just above and to the left of the blue stars is the supergiant Sher 25, which is probably just thousands of years (not even a blink in star-time) from a colossal supernova, when it will blow itself into smithereens, sending iron, lead, and all the heavier elements far into space, possibly to conglomerate into new planets. Sher 25 is already ejecting its mass as its structure breaks down. In a very short period of time, it will be gone.
So there is death here, but it's not murder. It's suicide.
at 12:28 AM