Podcaster: Richard Drumm
Title: Space Scoop: From Science Fiction to Science Fact!
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1149/
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:
From Science Fiction to Science Fact!
You’re probably wondering what on Earth is going on in the image in today’s album artwork! Unlike many of the wonderful photos that we bring you in Space Scoop, this picture is a computer graphic drawn by an artist. But this picture wasn’t conjured up by the artist’s imagination.
Instead, the artist worked with astronomers to, as accurately as possible, show us things in space that we can’t photograph.
For instance, the blue lines in the picture show the elliptical paths that the stars follow as they orbit. Obviously, these blue lines don’t really exist in space, like some cosmic road map, but an artist can draw them to help us see the invisible.
Meanwhile, the red line shows the path that a huge gas cloud called G2 is moving along. This cloud was first noticed in 2002.
But what are these stars and that gas cloud orbiting around? This is where we come to the reason behind this picture: Just above the UNAWE logo there is an invisible object called a black hole.
These objects are invisible because they swallow-up anything that gets too close – even light! Astronomers know that some black holes are giants, called a supermassive black hole or SMBH, and that there is one of these in the center of basically every large galaxy.
Then in 2006 astronomers were using an ESO instrument called the Very Large Telescope, the VLT, which is at the Paranal Observatory in Chile. They discovered that that cloud of gas called G2, with about 3 times the mass of Earth, was accelerating towards a very close encounter with the SMBH at the centre of our Galaxy.
The graphic shows what astronomers thought will happen to the gas cloud in the year 2021.
Our SMBH is called Sagittarius A* because it’s in the direction of the summertime constellation Sagittarius as seen from Earth. It’s called A because it’s the brightest radio source there and asterisk or “star” because that’s the designation for excited atoms and this was an exciting thing to find.
That 2006 observation was the first time ever that astronomers had witnessed a cloud of gas approaching an SMBH!
Then in May 2012 astronomers released the results of a study that began in June 2010 with the observation of what looked like a supernova in a 2.7 billion light year distant galaxy. But as they watched it, the supernova brightened very slowly. Not like a supernova at all.
It appears that the helium rich core of a star had been shredded to bits by the SMBH in the center of the galaxy that they’d been observing. The hydrogen gas outer layers of the star had probably been stripped away millions of years ago in previous encounters with the SMBH. So these monsters eat gas clouds fairly often.
But back to the Milky Way…
In late 2013, at 25 billion miles away from the SMBH, G2 had its closest approach to the SMBH and…
Nothing happened.
Well, almost nothing. It was slightly stretched by the gravity of the SMBH, but not very much. That graphic’s long red tail? — didn’t happen. It did get a speed boost from the approach, it was going 1.5 million miles per hour faster on leaving than when it was going toward the SMBH, but that’s about it.
So back to the drawing boards! New theories were floated that instead of it being just a gas cloud, that it had a small star embedded in it, making it more dense and better able to hold onto its gas.
Or it could be that the orbit calculations were inexact and G2 didn’t come as close to the SMBH as they’d thought. It’s also possible that the closest approach happened in May of 2014 instead of late 2013.
Astronomers aren’t sure what G2 really is at this point.
One thing that has happened, though, is that our SMBH in mid 2014 started putting out X-rays at 10 times the rate that it was doing before the close pass of G2.
So it’s possible that gas that was stripped off G2’s tail may have eventually spiraled down into the SMBH after all. Just not as much gas as they’d thought would get stripped.
It’s also possible that the increased X-ray activity is just something SMBHs do naturally and isn’t related to G2 at all.
Astronomers will be keeping a close eye on Sagittarius A* to see what happens.
Hey, Here’s A Cool Fact:
Even though G2’s approach was kind of a flop, we scientists learn from non-events too. In July of 2014 it was speculated that G2 is not an isolated bit of cloud at all.
Another gas cloud, not surprisingly called G1, which passed close to our SMBH in 2001 has almost the same orbit as G2. Thus they may be left over from the same parent star, and are separate lumps in a single large, lumpy gas stream in a messy orbit.
There may yet be fireworks to be seen in the center of our galaxy! So stay tuned!
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!