Podcaster: Richard Drumm
Title: Space Scoop: Not Your Average Superhero
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1226/
Description: Space scoop, news for children
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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Transcript:
This is 365 Days of Astronomy. 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.
Today’s story is: Not Your Average Superhero
A black hole is formed when a massive star is squashed into an incredibly tiny volume. This is the equivalent of squeezing the Earth into the size of a marble!
Packing so much material in such a small space gives black holes a superpower: Incredibly strong gravity that can be so strong that even light isn’t fast enough to reach escape velocity. It gets pulled back in.
It’s time for the adventures of Gravity Man!
Hmmmm. Needs work.
By the way, we sometimes shorten black hole to BH for convenience.
Around the point of no return, before disappearing forever into the black hole, any nearby material is accelerated to very high speeds.
This fast moving material experiences the same friction that warms your hands when you rub them together on a cold day. This makes it hot as all heck and causes the infalling matter to give off X-rays, which astronomers can observe using special X-ray telescopes in space.
In recent years, astronomers have discovered regions around black holes that are giving off a crazy amount of X-rays – a lot more than what should be possible. They call these things Ultra Luminous X-ray sources, or ULXes for short.
The 15 million light year distant galaxy pictured in today’s album artwork, is called M83, and is located in the constellation Hydra. Astronomers have discovered in it just such a weirdly powerful black hole ULX.
The galaxy is, of course, on the upper right of the graphic, and the quad split graphic on the lower left shows the before & after images for both the visual and X-rays. What a difference! There’s a tiny blue dot for the star in the visual after the event, but the X-ray image after the event is huge!
Astronomers still don’t fully understand what’s making these black holes mega-powerful, but it could be that they are a bit heavier than normal so-called “stellar mass” black holes. This is a black hole that is formed when a massive star collapses at its end.
A heavy black hole could pull in more material than a smaller black hole, and in so doing would make a lot more X-rays. The BH we’re talking about today has 100 times the mass of our Sun, which makes it somewhat heavier than a normal example of a stellar mass black hole.
Now it may be that this BH is at the very lowest end of the so-called “intermediate mass black hole” category. However, as the very heaviest stars do have up to 315 times the Sun’s mass, one could be forgiven for calling a 100 solar mass BH a stellar mass BH.
A bona fide example of an intermediate mass BH has yet to be found. Wikipedia’s entry on them gives a range of 100 to 1 million solar masses for intermediates, but there’s no citation there as of yet on that mass range estimate.
There’s nothing magical about the number 100 here. It’s just a nice place to draw the boundary. It could be that the intermediate mass category should start at 250 or so, but it’s just an arbitrary boundary.
Astronomers are keenly looking for a BH with 1,000 or so solar masses, so stay tuned here for news when they succeed!
Stellar mass black holes are said to typically have from 5 to 30 solar masses and show huge tidal forces as one approaches the event horizon. If you want to be “spaghettified” then you want a stellar mass BH. But nobody I know wants to be torn into a stream of loose atoms, so there ya go!
There is a different class of black holes that astronomers think is in the center of basically every galaxy: supermassive black holes. These puppies range from hundreds of thousands to hundreds of billions of solar masses.
The tidal forces there are large, to be sure, but the tides that spaghettify things happen inside the event horizon in the case of the supermassive black holes.
With stellar mass BHs the spaghettification takes place outside the event horizon and any X-rays that the stream of atoms emits aren’t trapped behind the event horizon.
So with stellar mass BHs we get to see the carnage.
And call it a ULX.
This remarkable ULX outburst event is direct evidence for a population of older, volatile, stellar mass black holes. This sudden brightening is one of the largest changes in X-rays ever seen for this type of object, which do not usually show dormant periods.
Hey, Here’s A Cool Fact:
When that black hole in the galaxy M83 erupted in 2011, it produced 3,000 times more X-rays than it had been producing before it became mega-powerful!
Wow.
Thank you for listening to 365 Days of Astronomy!
End of podcast:
365 Days of Astronomy
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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!