Daily Archives: June 26th, 2008

More Cosmic Destruction

Larry Klaes of the Tau Zero Foundation writes at the Centauri Dreams blog about how “explosive” the Universe really is and how we perceive the twinkling lights in the sky as a peaceful, beautific scene is severely flawed:

When we look up at the night sky with our eyes alone, everything about it seems calm and even peaceful. Aside from a passing airplane or satellite, only the occasional meteor or twinkling star indicate any natural activities up there. Otherwise, the Universe seems almost immobile and permanent, even when we watch the stars for a long while.

Recent news by the astronomy community shows just how much of an illusion this perception actually is. On May 14, NASA announced the discovery of the youngest local supernova remnant yet known, an object unpoetically known as G1.9+0.3, located near the center of our Milky Way galaxy about 26,000 light years from Earth.

Though most stars exist for ages far longer than human minds can conceive, they are not immortal. Some last for billions of years and eventually more-or-less quietly fade away; this will be the fate of our Sun.

More massive suns do not exist for quite so long, nor do they leave the Universe peacefully. These natural fusion reactors often end up in a titanic explosion called a supernova. Some lose their nuclear fuel, causing their cores to collapse and release huge amounts of energy in the process, leaving a neutron star or black hole in their wake. Other large suns that are part of a binary system where one star is a white dwarf create their death act when too much material from the giant star is pulled onto the white dwarf companion, causing its core to heat enough to create runaway nuclear fusion and tear itself apart.

Artist\'s conception of a supernova

White dwarf stars are not only formed in binary systems, main sequence single stars such as F, G and K types are capable as well. When these stars age, they use up most of their hydrogen fuel. Our sun is a type G, so it is theorized that as it ages and uses up its fuel, it will swell in size as it tries to fuse heavier elements like helium and lithium. The core starts to get more dense as it converts the heavier fuels into heavier yet materials, but the surrounding gas envelop expands. Eventually, the sphere will gulp down Mercury, Venus, Earth, Mars, Jupiter and eventually Saturn as it enters its red giant phase:

As a red giant, the Sun will have a maximum radius beyond the Earth’s current orbit, 1 AUm), 250 times the present radius of the Sun.[28] However, by the time it is an asymptotic giant branch star, the Sun will have lost roughly 30% of its present mass due to a stellar wind, so the orbits of the planets will move outward. If it were only for this, Earth would probably be spared, but new research suggests that Earth will be swallowed by the Sun due to tidal interactions.

Life of the Sun

Eventually the Sun will “blow” off the outer gas layers in a “semi-nova” (because it’s not massive enough to collapse into a full nova) and a white dwarf star will result.

Of course by then I fully expect the Solar System to be empty of life, either by Exodus, Diaspora, already extinct or transcension by Singulary(s) (or other means).

The Universe is an interesting, and violent place.

Even our own little corner of it has that “take a walk on the wild side” quality!

The Explosive Cosmos

Life cycle of the Sun