The galaxy has a very strange shape, which scientists think was caused by a large elliptical galaxy and a smaller spiral galaxy (like ours) running into each other a long time ago and squishing together. Everything in space is always moving, so collisions happen pretty regularly.
Part of it looks like an S turned on its side, with a bright disc sitting at an angle to the center of the S, and then two long, twisted shapes, that almost look like hooks in some pictures, coming out of the middle of the disc.
The bright disc is packed full of stars and more are being born all of the time, so they create a lot of light. It sits around Centaurus A’s central supermassive black hole. The supermassive black hole at the center of Centaurus A has the mass of 55 million suns like ours. The one in the center of our galaxy (the Milky Way) has a mass of 4 million times the mass of our sun.
Centaurus A Facts
• Centaurus A’s black hole is far more massive than the Milky Way’s, but to put it into perspective, the one in the center of one of our neighbors, M87, has a massive of 6.4 billion suns, and the largest black hole yet discovered is in S5 0014+81 with a mass of 41 billion suns.
• The twisted shapes are caused by very powerful jets (some are a million light years long!) of energy being shot from the black hole. They are made up of x-rays and radio waves. Centaurus A was one of the first places humans were ever able to detect radio waves coming from that was outside of Earth.
• The sideways S portion is the galaxy’s dust lane. A dust lane is an area of interstellar dust. Dust lanes give galaxies the pieces they need to create stars and planets, and Centaurus A’s is dense with lots of stuff for the galaxy to use. Centaurus A is called a starburst galaxy because it has over a hundred star-forming regions in the disc area that are always creating stars.
• All of these new stars make Centarus A very bright. It’s the fifth brightest galaxy that you can see in our night sky. For amateur astronomers in the southern hemisphere or lower latitudes (closer to the equator) of the northern hemisphere, it’s a great target to take a look at. What you would be able to see if your telescope was powerful enough would be a bright ball of light with the wavy dust lane crossing it.
• The radio and x-ray jets are thought by most people to be created by an explosive event that is happening on the edge right before the event horizon (the event horizon is the last possible point for light or matter to escape before being sucked in) before the black hole.
• They don’t know what the explosive event, or events are, or how they’re happening. Whatever is making them happen, the jets are being shot from the black hole very fast. The center part of the jets is moving at about half light speed,
• Along with all of the new stars that Centaurus A is creating, it’s also losing some. All stars have a life cycle, but only some explode and become a supernova. Two supernovae have been found so far inside Centaurus A. The first of them was classified as a type Ia supernova. The second is still being investigated.
• Type Ia supernovae happen in binary systems, which are just two stars that always orbit each other, where one of the stars has collapsed in on itself and become a white dwarf. White dwarves don’t explode on their own, and the heart of a white dwarf has slowly died out and stopped producing new energy.
• In a binary system, sometimes the white dwarf starts to steal some of the mass from the other star until the white dwarf gets has gained so much mass that it is kickstarted into burning again, and a chain reaction happens until the star explodes. Gaining too much mass to maintain stability is called reaching critical mass.
• Since it takes over 10 million years for light to reach us from the galaxy, these stars exploded over 10 million years ago. Since then, there have probably been many more exploding stars inside Centaurus A, due to its very high star count. Both professional and amateur astronomers are always scanning the skies to see if they can find anything new.
• Centaurus A is part of the Virgo Supercluster that contains at least a hundred galaxy groups and galaxy clusters. Our own galaxy is also part of the Virgo Supercluster. The Virgo Supercluster is part of the Laniakea Supercluster, which contains around 100,000 galaxies. As you can see, we have a lot of neighbors in space, including Centaurus A!
Centaurus A Profile
Other names: NGC 5128 (most common), Arp 153, PGC 46957, 4U 13322-42, Caldwell 77.
Location: Constellation Centaurus.
Distance: Approximately 10 to 16 million light years from Earth.
Brightness: Fifth brightest galaxy seen from Earth.
Where you can see it: From the southern hemisphere or lower latitudes (closer to the equator) in the northern hemisphere.
Special features: Warped S-shaped dust lane, fast production of new stars (starburst galaxy), and the extremely powerful jets coming from its black hole that have an unknown cause.