Podcaster: Richard Drumm
Title: Space Scoop: Handle with Care: Astronomers Build an Explosive Collection
Organization: 365 Days Of Astronomy
Description: Space scoop, news for children.
The South Pole is a hostile environment; it’s a frozen desert where temperatures can drop below -80°C.
Yet scientists have been flocking there for the last 8 years, because it’s one of the best places to go to answer a mystery: What shoots beams of tiny, almost undetectable particles at Earth?
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.
Today’s sponsor: This episode of 365 days Of Astronomy is sponsored by Erich Stenzel.
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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.
Handle with Care: Astronomers Build an Explosive Collection
Everyone loves to collect their favorite things. For some people that’s action figures or stickers. For others it could be stamps or seashells, and some people want to catch all the Pokemon with their app.
Collecting stuff is fun but it can also tell you something about the things you’re collecting. You might notice that all your stamps have something in common or your shells might tell you something about the creatures that lived in them.
Here’s a collection for you!
A group of astronomers in Japan has collected pictures of 1,800 rare and explosive supernova events, events where a massive star explodes in a big, big way.
This explosion is very bright and can takes months to fade away.
To find such a large number of supernovae, these astronomers captured images over a huge swath of the night sky.
They continued to take images of this area for six months to look for sudden bright bursts that gradually disappeared.
OK, the outbursts weren’t all that bright. They were dim. Kinda wicked dim even.
The astronomers used the Subaru Telescope on Hawaii’s Mauna Kea volcano to gather the images.
Their so-called “Hyper Subprime-Cam” camera was sensitive enough to detect the faint brightening of the 1,800 supernovae that they detected.
But among those 1,800 faint events were 400 detections of a special type of supernova. Type 1A supernovae.
OK, now for a little background on supernovae.
There are 2 main types. The one most of us astronomers think about first are the core-collapse ones, the Type 2 supernovae.
These Type 2 explosions are where a very massive star collapses under its own weight, making a neutron star or black hole in the aftermath of the explosion. Most of the 1,800 detections were of this type.
But those 400 Type 1A supernovae on the other hand, have a different story. Here we have 2 stars in orbit around each other, a pretty common occurrence in the Universe.
One star, over billions of years, slowly runs out of fuel in its core and evolves into a red giant star. This star has basically the same mass as it always had, but is waaaay larger in diameter.
It grows so large in fact that the outer parts of the star are effectively pushed away from the star and only the core of the star is left. We call this hot little remnant a white dwarf.
Then a billion years or so go by with the white dwarf happily orbiting the other star.
Eventually the other star does the same red giant thing the first star did, bloating up and pushing its outer layers out of its gravitational well.
Only there’s this dense white dwarf in an elliptical orbit around it. When the white dwarf gets close to the other star is strips away some hydrogen & helium gas from the red giant star.
The red giant wasn’t holding tightly onto the gas, so it was easy to steal.
The gas builds up on the surface of the dwarf over time, orbit after orbit, getting deeper and more massive.
Then something happens. Something catastrophic.
When the white dwarf reaches the critical mass of about 1.44 times the mass of our Sun, in a few seconds a substantial portion of the carbon & oxygen in the dwarf fuses into heavier elements and the star explodes.
But because the exploding star is always starting from that 1.44 solar mass starting point, the Type 1A supernovae are effectively always of the same intrinsic brightness.
Knowing this brightness and seeing how dim the star is in the night sky we can fairly easily calculate how far away the supernova was. We can use this technique to measure the size of our galaxy and the distance to other galaxies.
Among those 400 Type 1A supernovae were 58 Type 1As that were more than 8 billion light years away from Earth.
It took the team only 6 months to find these 58. The best the Hubble Space Telescope could do in 10 years of searching was 50 Type 1As at this distance.
So this was a great way to find super distant Type 1A supernovae and measure the distance to really, really far away galaxies.
The astronomers will next use the data from these distant explosions to chart the growth of the early Universe. The light from these supernovae left their host galaxies over 8 billion years ago when the Universe was young.
They’ll also study the effect of dark energy on the Universe’s growth and figure out how much the expansion rate has changed as the Universe has grown older.
Maybe they’ll learn more about the acceleration of the Universe’s growth rate. Right now the acceleration is attributed to dark energy, but that word is just a placeholder, a term we can use to describe what we’re talking about.
We have no idea what it is or even if it really exists. It may be that it exists and is responsible for the absence of curvature in the Universe, the flatness of the Universe, but we just don’t know for sure.
Hey Here’s A Cool Fact:
When supernovae explode, they send matter into space at up to 40,000 kilometers per second! At that speed it would take 10 seconds to get from the Earth to the Moon.
This is 13% of the speed of light!
Thank you for listening to the 365 Days of Astronomy Podcast!
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365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by Planetary Science Institute. 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 celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!