Podcaster: Richard Drumm
Title: Space Scoop: A Bridge Between Worlds
Organization:365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1707/
Description: Space scoop, news for children
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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 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.
A Bridge Between Worlds
Cosmic objects like to travel in groups. Moons orbit around planets, planets orbit around stars, stars orbit around the center of the galaxy and galaxies sometimes orbit around other galaxies.
As you already know, our galaxy is called the Milky Way. It’s a gigantic collection of stars, cosmic dust, gas and assorted other stuff. Stuff like the leftovers from supernovae and planetary nebulae. Cosmic flotsam & jetsam!
About 50 smaller galaxies are thought to orbit around our galaxy, although we can only see two with the naked eye. These two are called the Large and Small Magellanic Clouds, the LMC & SMC for short.
They aren’t visible from Northern latitudes, though. They’re just too far South for us Northerns to see.
Although we can see them without telescopes, studying them WITH telescopes is better. But seeing the Magellanic Clouds in detail has always been a bit difficult because they sprawl out over such a large area of the sky.
Try looking at an entire building through binoculars while standing next to it on the street and you might understand why this is.
Using the Gaia satellite launched by the ESA, we’re finally able to see our galactic neighbors in fabulous detail. We’ve found something very exciting — the two galaxies appear to be connected by a cosmic bridge.
The bridge, made of stars and gas, stretches across 43,000 light years of space. That’s more than four times the length of the LMC itself!
This bridge is at least partly made from stars being pulled out of the SMC by the LMC. This may have happened 200 million years ago, when the dwarf galaxies passed fairly close by each other.
The rest of the stars and gas might have been pulled out from the LMC by our Galaxy, the Milky Way. Pulled by our gravity!
Do a Google Images search for Magellanic Clouds and you’ll see them for yourself. Next to the stripe of the Milky Way you can see the two dwarf galaxies; the brighter blob of the LMC and the smaller, dimmer SMC.
You won’t see the bridge, though. It’s much too dim to show up in the wide field images like you see there on Google. So how’d the astronomers do it?
They looked for a particular type of star that varies in brightness, called an RR Lyrae star. These are old, metal-poor stars that are on the so-called “Horizontal branch” of the HR diagram, the Hertzsprung-Russell diagram.
This diagram is a graph where star colors are on one axis and the star’s brightness is the other axis. This diagram is like a roadmap of how stars change as they go through their life.
Using the Gaia satellite they found hundreds of these RR Lyrae variables and marked their locations on a map of that part of the sky.
They were quite surprised when they found the narrow bridge-like connection partly built of these RR Lyrae stars between the LMC & SMC.
Hey, Here’s A Cool Fact:
This research has also revealed that both the LMC and SMC are bigger than we thought! At each end of the bridge is a large, dim halo of those RR Lyrae stars. At the LMC it stretches as far as 20° from the center.
Thank you for listening to the 365 Days of Astronomy Podcast!
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!