Organization:365 Days Of Astronomy
Description: Space scoop, news for children.
Story about Orion nebula
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
The Scariest Space Monsters Live in the Biggest Galaxies
There are monsters lurking in space.
OK, not monsters like in the movies. Black Holes. Anything that gets too close to a Black Hole is pulled to it with such strong gravity that eventually it has no chance of escape.
The monster will gobble it up!
Even light – the fastest thing in the Universe – is doomed if it goes near one of these monsters. This is why Black Holes are black. They’re like a roach motel for matter & energy. You can check in but you can’t check out!
However, they’re not really holes and they’re not really empty.
Far from it.
Black Holes are actually filled with a lot of material that’s crammed into an extremely small region.
The matter that we and the world around us is made from seems solid, but is actually quite empty. There’s a lot of empty space in a seemingly solid rock and with enough gravity the rock can be compressed into a much, much smaller size.
How much smaller can you go?
To make a small Black Hole you would have to squash the Earth into a tiny ball that is only a few millimeters wide!
Astronomers know that some Black Holes are giants and that they are found in the centers of most galaxies. Maybe all galaxies, including our own galaxy, the Milky Way! These giant monsters are called Supermassive Black Holes or SMBHs for short.
Douglas Adams’ book “The Hitchhiker’s Guide to the Galaxy” says ‘Don’t panic!’ and it’s quite true with respect to SMBHs. The Earth and the rest of our Solar System is far enough away that they aren’t in any danger from our galaxy’s SMBH.
In fact, there are only a dozen or so stars that are close enough to someday get eaten.
Some of the SMBHs don’t have any material to eat, so they are quiet and are called quiescent. This is the situation here in the Milky Way.
But others have a veritable buffet table of cosmic goodies within reach. Tasty stars & gas & dust.
The SMBHs that are currently eating are easy to find in the Universe. They are called active galactic nuclei or AGN galaxies.
The doomed gas & dust collects in an accretion disc as it spirals into the black hole. The matter doesn’t fall straight into the black hole because it has some angular momentum.
The matter shines brightly in X-rays because it’s so hot. And it’s hot because of simple mechanical friction. It also shines brightly in visible light and radio waves as well. Then it disappears forever across the event horizon where not even light can escape.
We use X-ray space telescopes to find these AGNs since they’re bright in X-rays. It’s not like they’re hiding or anything, they announce their presence loudly!
Astronomers had expected to find most of the monsters that are currently feeding at the centers of medium-size galaxies.
However, observations of 593 AGNs were done back in 2011 with the ESO’s VLT at the Paranal Observatory in Chile. This has shown that they are mostly in the centers of galaxies that are 20 times bigger than what they had expected.
The astronomers say that this means that galaxy collisions aren’t the cause of AGN activity, even though such collisions were common in the crowded early Universe.
This surprising discovery means that astronomers will have to start over and figure out why their prediction was wrong.
But this is OK. This is how science works. We have to modify our understanding of how things are the way they are when new evidence comes along. We’ll have to make a new model and test it out.
Hey, Here’s A Cool Fact:
There is no shortage of these AGN galaxies. They are common at great distances. So great, in fact, that they represent the early Universe.
If you look closer to our neighborhood and don’t look so far away you see fewer of these AGNs. So the AGN stage of galaxy evolution is something that happened in the distant past of our Universe. We’ve kinda outgrown all the rough & tumble stuff.
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by Astrosphere New Media. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrate more discoveries and stories from the universe. Join us and share your story. Until tomorrow! Goodbye!