Something New Over the Sun
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Several weeks ago something new was spotted in the early morning skies in the constellation Scorpius, something which hundreds of years ago would have caused quite the uproar to say the least.
The new object, starlike in appearance, goes by the name V1280 Scorpii. By the time you read this it may have dimmed enough to require a telescope in order to be seen. But the point is: A new thing could be seen by the naked eye! The eternally unchanging skies changed for us, if only just for a couple weeks.
V1280 Scorpii is a nova, not to be confused with its more explosive sister, the supernova. But you can see in both names the root "nova," Latin for "new."
I'll explain what a nova is below, but it's interesting to note that just centuries ago actually seeing a new star appear in the sky was a paradigm shift of the first magnitude.
Back then the starry heavens were filled with the fixed stars, the never-changing canopy of lights arching over us from one horizon to another. For some they represented the sacrosanct realm of God where nothing varies. For many who lived during the time of Galileo or the famous astronomers Tycho Brahe and Johannes Kepler something new appearing in that hallowed sky was highly suspicious and went against the prevailing worldview.
But Tycho Brahe saw a new star, a "stella nova," in 1572 and using some simple math showed that it was not some atmospheric phenomenon, but something way, way, far away, where things were assumed to be fixed and unchanging.
He and Kepler and Galileo were part of a golden age of astronomy, when we started using events like novae and supernovae to see the glorious heavens as an extension of our physical universe and not some quintessential otherworldly firmament. The universe hasn't been the same since.
So what is a nova? Well, most of us are aware that a supernova is the explosive death of a big star. But a regular plain old "nova," sans the super - what's that?
Most stars end their lives with a whimper, with no explosive end. Our own star will give up the ghost that way. In ways beyond what I can discuss here, a star like the sun dies by shedding its outer layers, leaving behind only a white-hot core, christened a white dwarf.
Now that's pretty much the whole story if the star is all alone. But many of the stars up there are binaries, that is, they have buddy stars. That can make for quite a different scenario.
If the next door neighbor to a white dwarf grows up and out into what is called a red giant it is quite possible that the white dwarf may actually find itself stealing away some of its bloated friend's gas.
In stealing away the hydrogen from the other star, it now can form a new layer of hydrogen on its own surface. An old dead star is suddenly rejuvenated, if only temporarily.
Now understand that hydrogen is the fuel of stars, a stellar staple so to speak. The old dense, hot, white dwarf, previously depleted of fuel, now sees an opportunity to come alive again. The white dwarf's intense gravity crushes the hydrogen on its surface and heats it to about 40 million degrees Fahrenheit. This is enough to cause a fusion reaction (think nuclear weapons) and the surface erupts in a flash of energy.
The whole complicated process can last from weeks to months, and if the star is close enough to earth we can see a "new star," a nova, in the night sky.
If the white dwarf survives, this whole process may happen again, and again, and again, providing Earthlings with successive novae in following decades or centuries.
The nova may be a mere physical phenomenon, but it still inspires awe and wonder in the heavens, something the cold sciences will never take from us.
Posted by Mark Ritter at 2007.03. 4 02:09 PM | Comments (0)
