Fifty-six million years ago, a dying star in galaxy we call M100 exploded in a truly cataclysmic blast and went supernova. This week in the universe, after traveling toward Earth for 56 million years at 186,000 miles per second, the light from this stellar explosion reached astronomers on Earth and Supernova 2006X was named by the International Astronomical Union.



Just what is a supernova?

One of the most energetic explosive events in the known universe is a supernova. Supernovae occur at the end of a star’s lifetime, when a star’s nuclear fuel is exhausted and it is no longer supported by the release of nuclear energy.

If the star is particularly massive, then its core will collapse, and in so doing, will release a huge amount of energy. This will cause a blast wave that ejects the body of the star into interstellar space. When I have referred in other columns to the fact that we are all made of star stuff, it is because the universe is really a mixing bowl of give and take. The dust from this exploding star will now drift for trillions of miles until coming to rest somewhere and forming a nebula that may eventually collapse and form a new star/planet system.

While many supernovae have been seen in nearby galaxies, they are relatively rare events in our own galaxy. The last to be seen in our Milky Way galaxy was Kepler’s star in 1604. The most famous nearby supernova remnant is the Crab Nebula. There is an image of the Crab Nebula on my gallery at http://tinyurl.com/apxh9.



The supernova’s home galaxy

Supernova 2006X resides in a galaxy we call M100. This galaxy was the 100th object labeled by the great French astronomer Charles Messier less than a month after it was discovered by Pierre Méchain in 1781. M100 is one of the brightest member galaxies of Virgo Galaxy Cluster, of which we are a member.

Majestic on a truly cosmic scale, M100 is known as a grand design spiral galaxy. This moderately large galaxy contains over 100 billion stars and displays a set of well-defined spiral arms and is similar to our own Milky Way galaxy. Viewing this gorgeous spiral galaxy causes me to wonder just who or what is responsible for such dramatic beauty and order in our universe.



M100 is like a fellow Texan

Our home galaxy, the Milky Way and M100 reside in the Virgo Galaxy Cluster contains approximately 2,000 member galaxies. The Virgo Cluster would be considered the state we live in if you consider that Earth is our house, the solar system our neighborhood, and the Milky Way galaxy our county. The Virgo Cluster dominates our intergalactic neighborhood and is the physical center of our local supercluster.

The Virgo Cluster influences all the nearby galaxies and galaxy groups by the gravitational attraction of its enormous mass. Eventually, gravity will cause many of these galaxies to fall into this giant cluster, which will increase in size due to this effect. Our local group of galaxies has experienced a speed-up of 100 to 400 km/sec speeds toward the Virgo cluster and will fall and merge into or be eaten by the cluster creating one dramatic super galaxy out of thousands of individual galaxies that each contain hundreds of billions of individual stars.



Back to the supernova

SN2006X is a Type Ia supernova. Thanks to computerized sky surveys, SN2006X was found one to two weeks before its maximum light reaches us on Earth. Right now, astronomers all over the world are scrambling to take pictures of the supernova and record its brightness.

Despite the nearly full moon, wind and cold, I managed to capture one of the earliest images of SN2006X early Feb. 11. I estimated the brightness of SN2006X to be 14.13. This means M100 is more than 10,000 times dimmer than you can see with the unaided eye.

SN2006X is the fifth supernova to observed in the galaxy M100 in the past 100-plus years we have been looking. The last supernova in M100 occurred in 1979 and was called 1979C.



What we learn from Type Ia supernovae

The most interesting and important (for scientists) aspect of Type Ia supernovae is that they are all basically the same brightness at their source. Because of this, Type Ia supernovae are called “standard candles” by scientists.

By measuring their brightness (apparent magnitude), scientists can determine several important things. By comparing the difference between multiple supernovae in the same galaxy over time, we can precisely determine their distance from Earth. By precisely determining change in distance over time, we can determine how fast they are moving, which tells us how fast the Universe is expanding.



What would happen here?

The last supernova in our galaxy occurred 400 years ago, making us about 300 years overdue for the next one.

The instantaneous energy released by a supernova is greater than that released by an entire galaxy of stars. If the nearby red supergiant star Betelgeuse went supernova tomorrow, it would be clearly visible by day, be as bright as the moon and cast distinct shadows at night. Our solar system would receive a significant, but not lethal, dose of radiation from a nearby supernova.

We would probably lose many satellites, especially the distant communications satellites. Life would change for a while, but the human spirit would adapt, and we would overcome adversity once again.

Max Corneau is a NASA/JPL Solar System Ambassador, was the first fully qualified Army Reserve Space Operations Officer and currently Lieutenant Colonel in the Army Reserve. He is an avid amateur astronomer and member of the Texas Astronomical Society and the Astronomical League.

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