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Supermassive Black Holes

The Universe >

So, you’re thinking of taking a vacation this year to the center of the galaxy. You’ll just load up the luggage, put the kids in the back, and off you’ll go to enjoy the splendors of the galactic nucleus. Here’s my humble travel advice: Don’t do it!

[FAR LEFT: Ground based image of Galaxy NGC7052. NEAR LEFT: The tiny nucleus of the same galaxy (from Hubble) shows the swirling whirlpool of "stuff" referred to in this article. The black hole is WAY down deep inside.]

As splendorific as it may seem, your journey would be a one-way trip. For starters, it’s more than 30,000 light years away, nearly 200,000 trillion miles. Even Costco doesn’t have enough snack items to keep you fed for a journey that long.

But most importantly, at the center of our galaxy there is… (cue the scary music) a supermassive black hole!!! You may recall that a black hole is an object whose gravity is so intense that not even light can escape its grasp!

So how do we know there is a star-swallowing, gas-guzzling, dust-devouring, supermassive black hole there?

All over the universe, whenever astronomers peer deep down into the center of some distant galaxy, there is nearly always something weird happening - something dark and sinister.

Remember that a galaxy is a collection of usually hundreds of billions of stars. At the center of a galaxy, called the nucleus, there are gas and dust and stars all spiraling around Something in the center. Careening is a more accurate. Careening out of control is even better.

Objects going around nearby a spiraling center always move faster than objects out farther away. Think of a round backyard pool with a flock of rubber duckies floating around in it. Now imagine stirring the waters gently with some gigantic wooden spoon. The duckies toward the middle of the pool, near the central “whirl,” will travel faster than the duckies out near the edge.

Now suddenly a hole opens up at the bottom center of the pool, a hole that actually empties the water from the pool into some imaginary sewer drain below. The swirling waters will start picking up speed, spiraling faster and faster. As the water drains, it will swirl so quickly that a whirlpool will form. Now the little duckies near the center are swimming at breakneck speeds as they plunge down to certain ducky death.

This is what we see at the center of galaxies. The stars and gas and dust there are traveling way faster than they should – unless there is an open galactic drain at the center that is very small with intense gravity. It would have to have a mass equal to millions or billions of suns.

But the best telescopes can’t see a thing there. Which is precisely why a black hole is the prime suspect for our cosmic drain. A black hole’s intense gravity would spin the place into a frenzy, yet remain unseen.

Even the most supermassive black hole that we suspect is out there is only the size of our solar system. In our tiny human scale that may be huge. But in the grand scale of a galaxy, it is miniscule. For comparison (and in preparation for the SATs), the size of a galaxy is to its central blackhole as a football stadium is to an atom! The black holes are virtually impossible to pick out.

So you see, although a family trip to the center of the galaxy may sound adventurous, it is really a suicide mission into the depths of a monster. Once again, the Earth is your friend.

There are images of black hole terror waiting now to scare you at firstlightastro.com/iColumn. Beware!

Until next time, clear skies!

Have any supermassive questions? Mark Ritter can be reached at ritter@firstlightastro.com

Galaxy size / black hole relationships

More size relationships.

View some outstanding Quicktime movies of central supermassive blackhole in Centaurus A

See a wonderful mpg movie taking you from outside of a galaxy right down to the core. You can feel the swirl. ;)

Posted by Administrator at 2001.03.18 08:43 AM | Comments (0)

Castor and Pollux

Observing >

March puts above our wondering heads the mythological Gemini twins – Castor and Pollux. Let’s do a little mythological background check to see how the Twins got there.

Once upon a time, according to Greek myth, Zeus, long known for his out-of-control infidelity, “visited” a certain beauty named Leda on her wedding day. To make a long and naughty story short, Leda ended up simultaneously giving birth to two sets of twins – one set fathered by Zeus, one set by her husband. One of the Zeus twins was Pollux, while Castor was a twin from Leda’s husband.

No matter that they were of different fathers, or that Pollux was immortal and Castor not – the “twins” got along just like the best of friends.

Together they saved the Argo fleet, fought valiantly in battle, stole some women on their wedding day, engaged in cattle thieving – all the typical exploits of Greek heroes. Sadly, the cattle coveting incident lead to the killing of Castor.

Pollux was upset to say the least. Trying to be a sympathetic dad, Zeus told Pollux to come on up to Olympus. But Pollux would not. How could he enjoy Olympus if his best “twin” buddy was imprisoned with mortals in the underworld?

So Zeus compromised and allowed the brothers to spend alternating days in Hades and on Olympus.

Later Greek writers, the ancient ancestors of today’s happy-ending American television writers, rewrote the script and had Zeus put the Twins in the starry abode where we see them now. (Note: Some astrophysicists do not accept this explanation of how the two stars got there.)

So where are The Twins exactly? They are the two bright stars above your head in the early evening. (On Monday night, the Moon is right next to them.)

Castor is the bright star slightly more northwest than the other, with a slight bluish tint. A decent telescope reveals that Castor is really a “visual binary” – called Castor A and Castor B - the first of its kind discovered. Regular readers here will remember that binaries are two stars that are gravitationally bound and revolve around each other.

Castor A is itself another binary system whose two huge stars are so close they are almost in contact! In fact, they are so close that even our best telescopes can make out only one star there.

Castor B is also a binary (!) made of two huge stars that are even closer and take a mere three days to go around each other.

Beyond these pair of pairs is yet another faint pair! All these stars are gravitationally bound to each other, making what we call “Castor” a six-star system.

Castor’s brother, Pollux, is the rather pinkish star next door. It’s that faint orangey sort of color because it is in its red giant stage. That is when a star is about ready to shuffle off its mortal coil and expands out to enormous proportions. When it expands, the surface cools down and takes on a reddish color.

And – surprise! - this twin is also a binary system. It appears Castor and Pollux were put by early mythologists in the perfect place, an area full of twins, some related, some not.

The downside for these starry twins is that they, and all the stars in their systems are, unlike their mythological namesakes, not immortal. Most of them will blow out or blow up in the next millions of years.

Posted by Administrator at 2001.03. 4 08:45 AM | Comments (0)



Looking for something?	« February 2001 \| Main \| April 2001 » Supermassive Black Holes The Universe > So, you’re thinking of taking a vacation this year to the center of the galaxy. You’ll just load up the luggage, put the kids in the back, and off you’ll go to enjoy the splendors of the galactic nucleus. Here’s my humble travel advice: Don’t do it! [FAR LEFT: Ground based image of Galaxy NGC7052. NEAR LEFT: The tiny nucleus of the same galaxy (from Hubble) shows the swirling whirlpool of "stuff" referred to in this article. The black hole is WAY down deep inside.] As splendorific as it may seem, your journey would be a one-way trip. For starters, it’s more than 30,000 light years away, nearly 200,000 trillion miles. Even Costco doesn’t have enough snack items to keep you fed for a journey that long. But most importantly, at the center of our galaxy there is… (cue the scary music) a supermassive black hole!!! You may recall that a black hole is an object whose gravity is so intense that not even light can escape its grasp! So how do we know there is a star-swallowing, gas-guzzling, dust-devouring, supermassive black hole there? All over the universe, whenever astronomers peer deep down into the center of some distant galaxy, there is nearly always something weird happening - something dark and sinister. Remember that a galaxy is a collection of usually hundreds of billions of stars. At the center of a galaxy, called the nucleus, there are gas and dust and stars all spiraling around Something in the center. Careening is a more accurate. Careening out of control is even better. Objects going around nearby a spiraling center always move faster than objects out farther away. Think of a round backyard pool with a flock of rubber duckies floating around in it. Now imagine stirring the waters gently with some gigantic wooden spoon. The duckies toward the middle of the pool, near the central “whirl,” will travel faster than the duckies out near the edge. Now suddenly a hole opens up at the bottom center of the pool, a hole that actually empties the water from the pool into some imaginary sewer drain below. The swirling waters will start picking up speed, spiraling faster and faster. As the water drains, it will swirl so quickly that a whirlpool will form. Now the little duckies near the center are swimming at breakneck speeds as they plunge down to certain ducky death. This is what we see at the center of galaxies. The stars and gas and dust there are traveling way faster than they should – unless there is an open galactic drain at the center that is very small with intense gravity. It would have to have a mass equal to millions or billions of suns. But the best telescopes can’t see a thing there. Which is precisely why a black hole is the prime suspect for our cosmic drain. A black hole’s intense gravity would spin the place into a frenzy, yet remain unseen. Even the most supermassive black hole that we suspect is out there is only the size of our solar system. In our tiny human scale that may be huge. But in the grand scale of a galaxy, it is miniscule. For comparison (and in preparation for the SATs), the size of a galaxy is to its central blackhole as a football stadium is to an atom! The black holes are virtually impossible to pick out. So you see, although a family trip to the center of the galaxy may sound adventurous, it is really a suicide mission into the depths of a monster. Once again, the Earth is your friend. There are images of black hole terror waiting now to scare you at firstlightastro.com/iColumn. Beware! Until next time, clear skies! Have any supermassive questions? Mark Ritter can be reached at ritter@firstlightastro.com Galaxy size / black hole relationships More size relationships. View some outstanding Quicktime movies of central supermassive blackhole in Centaurus A See a wonderful mpg movie taking you from outside of a galaxy right down to the core. You can feel the swirl. ;) Posted by Administrator at 2001.03.18 08:43 AM \| Comments (0) Castor and Pollux Observing > March puts above our wondering heads the mythological Gemini twins – Castor and Pollux. Let’s do a little mythological background check to see how the Twins got there. Once upon a time, according to Greek myth, Zeus, long known for his out-of-control infidelity, “visited” a certain beauty named Leda on her wedding day. To make a long and naughty story short, Leda ended up simultaneously giving birth to two sets of twins – one set fathered by Zeus, one set by her husband. One of the Zeus twins was Pollux, while Castor was a twin from Leda’s husband. No matter that they were of different fathers, or that Pollux was immortal and Castor not – the “twins” got along just like the best of friends. Together they saved the Argo fleet, fought valiantly in battle, stole some women on their wedding day, engaged in cattle thieving – all the typical exploits of Greek heroes. Sadly, the cattle coveting incident lead to the killing of Castor. Pollux was upset to say the least. Trying to be a sympathetic dad, Zeus told Pollux to come on up to Olympus. But Pollux would not. How could he enjoy Olympus if his best “twin” buddy was imprisoned with mortals in the underworld? So Zeus compromised and allowed the brothers to spend alternating days in Hades and on Olympus. Later Greek writers, the ancient ancestors of today’s happy-ending American television writers, rewrote the script and had Zeus put the Twins in the starry abode where we see them now. (Note: Some astrophysicists do not accept this explanation of how the two stars got there.) So where are The Twins exactly? They are the two bright stars above your head in the early evening. (On Monday night, the Moon is right next to them.) Castor is the bright star slightly more northwest than the other, with a slight bluish tint. A decent telescope reveals that Castor is really a “visual binary” – called Castor A and Castor B - the first of its kind discovered. Regular readers here will remember that binaries are two stars that are gravitationally bound and revolve around each other. Castor A is itself another binary system whose two huge stars are so close they are almost in contact! In fact, they are so close that even our best telescopes can make out only one star there. Castor B is also a binary (!) made of two huge stars that are even closer and take a mere three days to go around each other. Beyond these pair of pairs is yet another faint pair! All these stars are gravitationally bound to each other, making what we call “Castor” a six-star system. Castor’s brother, Pollux, is the rather pinkish star next door. It’s that faint orangey sort of color because it is in its red giant stage. That is when a star is about ready to shuffle off its mortal coil and expands out to enormous proportions. When it expands, the surface cools down and takes on a reddish color. And – surprise! - this twin is also a binary system. It appears Castor and Pollux were put by early mythologists in the perfect place, an area full of twins, some related, some not. The downside for these starry twins is that they, and all the stars in their systems are, unlike their mythological namesakes, not immortal. Most of them will blow out or blow up in the next millions of years. Posted by Administrator at 2001.03. 4 08:45 AM \| Comments (0)
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