Swan Song

Cygnus the Swan is one of the easiest constellations to find over America. It is called the Northern Cross because its t shape makes it stand out. It is filled with features of interest to beginning astronomers.

Deneb, the star at the top of the t, forms a giant triangle with the blue star Vega in Lyra and Altair in the constellation Aquila. Deneb is a supergiant, 70,000 times brighter than the sun. It is also near a beautiful cloud of stars and gas called the North American Nebula.

Sadr is a bright star where the 2 bars of the cross meet. Albireo, the star near the bottom of the cross, is really a double star made of a golden yellow star next to a beautiful blue star.

In the summer the t lies its side, but in December it becomes an upright cross for a wonderful Christmas effect. Still, Cygnus is now known for a lot more than its brightness and beauty.

Between Sadr and Albireo is a blue supergiant called HDE 226868, near a star called Eta Cygni, about 5000 light-years from Earth.

In the early 1970’s scientists using a satellite above the earth’s atmosphere discovered x-rays coming from the vicinity of HDE 226868. They know the presence of x-rays always means something somewhere is very hot!

HDE 226868 is a star about 30 times more massive than the sun. But it appears to have an unseen companion of about 14 solar masses and they orbit one another every 5.6 days.

Since the invisible object can not be seen, it was named Cygnus X-1. How could it generate x-rays and nothing else? The most accepted explanation is the object is using its powerful gravity to steal plasma from the star. The hot gasses go around the object before they are pulled inside, much like water spirals around a vortex before it goes down a drain.

As the plasma goes into a spiral, the gasses accelerate to such a tremendous speed they give off energy at the x-ray wavelengths. There is little light for us to see. What kind of object could generate that much gravity? The best answer we have is that X-1 is a black hole.

In the 1960’s astronomers discovered objects in the deepest depths of space to the outer edge of the known universe. The mysterious bodies were moving away at extremely high speeds and emitting tremendous amounts of energy in the visible light and radio spectra. A single one of these objects could emit as much light as 100 billion suns.
They were dubbed quasars, or “quasi stellar radio sources.” And about 100,000 of them have been discovered so far.

Where do they get their enormous amounts of energy? A good power source would be black holes at their core that could swirl the gasses around them at super high speeds and generate the energy we observe.

What would it be like to be near a black hole? Let us listen to a tale from the future.