Podcaster: Richard Drumm
Title: Space Scoop: Our Galaxy Is Young At Heart
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1545/
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:
Our Galaxy Is Young At Heart
If you stand in a very dark spot on a moonless night, you might see a faint fuzzy glow stretching all the way across the sky, with a glowing milky-white bulge, in the direction of the constellation Sagittarius. This is our Galaxy, our home, the Milky Way.
The ancient Greeks called this “galaxias kyklos” meaning “milky circle.” This is where we get the term “galaxy” and also the name of our galaxy, the “Milky Way.”
For a long time it was thought to be a fuzzy cosmic cloud, but around the year 1610 Italian astronomer and mathematician Galileo Galilei pointed his new, home-built telescope at it. He was astonished to see that it’s actually made up of millions of stars!
They’re packed so tightly together that our naked eyes can’t see them as individuals; instead they blend together to create a diaphanous, glowing stripe. But what’s the bulge at its center?
That bulge is the busy heart of our galaxy. But even today, with telescopes much more advanced than Galileo’s, we struggle to see exactly what lies inside the bulge. This is mostly because of cosmic dust, which blocks starlight before it reaches our telescopes.
You can easily see the dust lanes in the galaxy in the northern hemisphere’s summertime skies. The Milky Way is split in two by a wide dark strip called “The Great Rift”. In the Southern Hemisphere there’s a dust lane called “The Emu” which starts near the galactic bulge in Sagittarius and ends at the Southern Cross. This is cosmic dust.
Now this “dust” is different from the dust under my bed. That dust is made of hair and broken fibers of cotton from my bedding. Cosmic dust on the other hand is composed of gasses like hydrogen, helium and oxygen and solid things like tiny bits of silicon, iron and carbon.
Even though the dark dust lanes look to our eyes like nothing gets through, there is a type of light that can travel through cosmic dust, this is infrared light. By mounting onto their telescopes special cameras that detect infrared, astronomers are able to peer through the curtains of cosmic dust to reveal what lies behind. By doing this, they are currently discovering huge numbers of new objects, including star clusters and exploding stars!
The most recent discovery is a new and unexpectedly young group of stars right in the middle of the galaxy. The red dots on the artist’s impression graphic in today’s album artwork shows the location of the group of youngsters. The gold star shows where we are!
In this research, ESO astronomers used the VISTA telescope, the Visible and Infrared Survey Telescope for Astronomy, at the Paranal Observatory in Chile. It’s situated on a peak less than a mile North of the VLT, ESO’s Very Large Telescope. They detected 655 Cehpeid variable stars. These stars brighten on a regular basis that is directly proportional to the star’s intrinsic brightness. As a result, the distance to the stars can be easily calculated.
This so-called “period-luminosity relationship” was discovered in 1908 by one of the greatest astronomers of all time, Henrietta Swan Leavitt of Harvard University.
But there is a catch — Cepheids are not all the same — they come in two main classes, one much younger than the other. Out of their sample of 655 the team identified 35 stars as belonging to a sub-group called classical Cepheids – young bright stars, very different from the usual, much more elderly, residents of the central bulge of the Milky Way.
The team gathered information on the brightness & pulsation period, and then deduced the distances of these 35 classical Cepheids. Their pulsation periods, which are also closely linked to their age, revealed their surprising youth.
The ages of these classical Cepheids provide solid evidence that there’s been a previously unconfirmed, continuous supply of newly formed stars into the central region of the Milky Way over the last 100 million years.
Mapping these 35 Cepheids that they discovered, the team has traced an entirely new feature in the Milky Way — a thin disc of young stars stretched across the galactic bulge. This new component of our home galaxy had remained unknown and invisible to previous surveys as it was buried behind those thick clouds of dust.
Its discovery demonstrates the unique power of the VISTA telescope, which was designed to study the Milky Way’s deep structures by wide-field, high-resolution imaging at infrared wavelengths.
Previously we thought the center of the Milky Way only contained old stars. But this proves that brand new stars have been forming there recently. So it turns out the heart of our galaxy is much younger than we thought!
You kids get off my lawn!
Hey Here’s a Cool Fact:
Our Solar System is located halfway between the center of the Galaxy and the outer edge. It takes 26,000 years for light from the central bulge to reach us on Earth! When that light left there the Pliocene-Quaternary ice age was still going on! We humans hadn’t even invented agriculture 26,000 years ago!
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 NUCLIO. 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 celebrate cosmic light as light is our info messenger in the universe. Join us and share your story to celebrate the International Year of Light. Until tomorrow! Goodbye!