Jimmy Westlake's Celestial News column appears Tuesdays in the Steamboat Today.
Find more columns by Westlake here.
Steamboat Springs An exploding star in a galaxy far, far away has created quite a stir in the astronomical community this week. The exploding star, or supernova, could become the brightest such explosion in a generation.
Supernovas within our Milky Way galaxy are exceedingly rare. The most recent one was in 1604, before the invention of the telescope, and it was observed by such astronomical giants as Galileo and Kepler. It became the brightest object visible in our nighttime sky and was even seen in daylight for several weeks.
When averaged over the past 2,000 years, a naked-eye supernova has been observed in our galaxy about once every 300 years. Statistically speaking, that means we are way overdue.
That’s not to say that astronomers haven’t had any supernovas to study. There are billions of other galaxies in the universe, and there’s almost always a faint supernova or two out there to be studied. What we’ve learned is that a star can explode as a supernova for a couple of different reasons. One way is when a red giant star dumps matter down onto the surface of a very compressed white dwarf companion star and sends it over the Chandrasekhar Limit. The result is a colossal ka-boom called a Type 1A supernova. A Type II supernova occurs when a massive star runs out of nuclear fuel and implodes under its own weight. Don’t worry — our sun has no companion star nor is it massive enough to implode when it dies, so our star is not destined to explode as a supernova.
In 1987, a star exploded in a neighboring galaxy, the Large Magellanic Cloud. At a distance of 170,000 light years, this exploding star became as bright in our sky as one of the stars in the Big Dipper.
What could become the brightest external supernova since 1987 has just exploded in the picturesque Pinwheel Galaxy, also known as M101. Astronomers first saw the exploding star, dubbed SN2011FE, on Thursday while it still was brightening. When it reaches its peak magnitude in a week or so, it might become visible in an ordinary pair of binoculars.
M101 is located near the end of the Big Dipper’s handle and is about 21 million light years away. That means that this once-in-a-generation binocular supernova really blew up 21 million years ago and the light from the explosion is just now reaching Earth.
Exciting? Yes. But we are still waiting for the Big One.
Jimmy Westlake teaches astronomy and physics at CMC’s Alpine Campus.