SN1987A: The story of a supernova

(The best all-time supernova is, of course, SN1604. It’s my personal favorite.)

What is SN1987A? With a name that technical, it seems like you’d need a decoder ring to understand it.

Just remind yourself that astronomers are not necessarily the most poetic bunch.

You don’t have to be a DaVinci Code master to unravel the meaning of “SN1987A”. If you can handle Blue’s Clues, you can handle astronomical abbreviations:

• SN = supernova.
• 1987 = AD.
• A = first.

The first observed supernova in 1987 has given us plenty to study. Supernovae have inspired scientists through the course of history, but in the year 1987, we had all sorts of neat tools ready & waiting for just the right explosion.

A supernova is the largest explosion in the known universe. There is so much energy that the blast shines brighter than an entire galaxy. Imagine how much light and energy our own sun will produce over it’s entire lifetime... well, a supernova creates even more. In one burst. There are reports from the Middle Ages of supernovae that were seen in the sky during the light of day.

Deep in the center of a star lives a nuclear reactor. It’s energy comes from the fusion of hydrogen atoms into helium atoms. These light-weight elements produce just the right amount of energy to support the star against its own gravity; it is a stable furnace, floating through space.

When a star’s gas tank starts creeping toward E, it doesn’t sputter like a starving engine. The force of the nuclear reaction is too great. Instead, the star expands. As it grows larger, it begins to form heavier elements like iron and carbon.

Once the last bit of fuel is finally burned up, the excitement begins. Without the hydrogen to helium reactions that counterbalanced the star’s tremendous gravity, the remaining mass collapses toward the center. Then, like a superball, the mass is bounced back out in a catastrophic explosion.

The massive amount of heat, radiation, dense mass and strong gravity in a supernova is the source of all the heavy elements in the universe. The remnants of supernovae eventually cluster together to form new stars. Our own sun is believed to be a third generation star.

Depending on the mass to gravity ratio, what remains of the star after the explosion becomes either an ultra-dense neutron star, or an infinitely dense black hole.

Radiation and gamma rays are emitted from supernovae. Something else that gets flung out into open space are the magical particles called neutrinos. This brings us to SN1987A.

Nearly impossible to find, neutrinos were merely theoretical until they were detected in the mid 1950’s. Scientists have been at work ever since, finding neutrinos that are generated by nuclear reactions on earth as well as those generated by the sun.

On a peaceful day in 1987, neutrino observatories in the United States, Japan, and Eastern Europe had a sudden burst of activity.

In 13 seconds, a total of 24 particles were registered throughout the planet. Three hours later, the light from SN1987A was finally visible to Earth. This is the only source of neutrinos that has ever been confirmed, apart from our own planet and sun.

It was close enough to see with the naked eye. The star exploded in the Large Magellanic Cloud, near the edge of the Tarantula Nebula. It is 168,000 light years away, which means the event occurred 168,000 years before it was spotted. (That was 161,000 B.C.)

The victim was a star named Sanduleak -69º 202a. It was a blue supergiant – a surprise, because at that time nobody thought this type of star could create a supernova.

Scientists think that a second star may have been orbiting Sanduleak -69º 202a, creating a binary system. The energy provided by this second star would have boosted the dying blue star into a full blown supernova.

The star was surrounded by a giant dust cloud which absorbed the shock wave. Good news: the emissions got brighter and easier to see when they collided with the cloud. Bad news: the cloud now obscures our view of the core. It is not yet clear whether the supernova resulted in a neutron star or a black hole.

Remember, supernovae are the source of heavy elements in the universe. The iron in your own blood was generated by an exploding star. Hard to believe? Consider this: all by itself, SN1987A created enough iron to equal the mass of 20,000 planet Earths.

The star exploded in 1987, but the Hubble was not launched until 1990. When the space telescope finally settled into orbit, it set sights toward the Tarantula Nebula.

Hubble’s observations have revealed many new details about the stellar catastrophe. Some theories about supernovae have been confirmed, some disproven. For example, scientists expected the blast to be spherical. Instead, Hubble pictures show that it’s shaped like a jellybean.

Since it’s launch, Hubble has snapped hundreds of pictures of the supernova. All eyes remain fixed on Large Magellanic Cloud.

The ring of dust surrounding SN1987A is still being clobbered by debris. It's about one light year wide, and It glows brighter each year. As time moves forward, the ring will eventually generate enough energy that it will light up the entire area.

Imagine what Hubble will see once the floodlights turn on!