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This composite image shows new details of the aftermath of a massive star that exploded and was visible from Earth over 1,000 years ago.

Dying Stars Write Their Own Swan Songs

By Geoff Brumfiel NPR

Alicia Soderberg studies the death of stars. Often, these final moments come as violent explosions known as supernovae. They’re spectacular events, but catching one as it unfolds can be tricky.

“You have to be in the right place at the right time, and often we’re not,” says the professor in Harvard’s astronomy department. “So all you can do is do a stellar autopsy and go back and try to pick up the pieces and try to figure out what happened.”

Soderberg’s autopsy involves collecting every signal her team can from the explosions: radio waves, light, X-rays. They try to put this information together in a way that makes sense. And often that’s hard to do. “The data analysis itself is very detailed,” she says

A few years ago, Soderberg met a graduate student named Wanda Diaz-Merced. Diaz-Merced lost her eyesight years ago, so she studies astronomy not with sight, but with sound.

“I have been able to listen to meteors passing through the atmosphere, solar storms, that is just to give you a gist,” she says. The data from stars, comets and planets all sound different. “Every sound I listen from the skies, it has its own voice.”

Soderberg and her team worked with Diaz to turn the deaths of stars into songs. Each signal collected in the autopsy gets its own part in the orchestra:

“The Radio gets the drums, the X-ray gets the harpsichord, and everything in between gets a different instrument, like a violin or a flute,” Soderberg says. She presented the first of these songs this week at the American Astronomical Society annual meeting in National Harbor, Md.

When Soderberg listens to these songs, she started to hear things. Things she hadn’t noticed when she looked at the data.

Each supernova sounds different, because each star dies in a different way.

“Stars can [die] by running into each other for example, like a car crash, or they can die by just running out of fuel,” she says. “A lot of stars will do interesting things before they die like pulsate or spin or get overheated.”

The songs map the story of the star as it explodes and expands and cools into a cloud of gas and dust.

But these aren’t only deaths. These supernova explosions release enormous quantities of elements like carbon, oxygen, nitrogen. Elements we need; elements we’re made of.

“I mean, supernovae fertilize the universe,” Soderberg says. “We wouldn’t be here if it wasn’t for supernovae.”

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

Transcript :

ROBERT SIEGEL, HOST:

This week, thousands of astronomers gathered just outside Washington, D.C. for their annual meeting. The talk there was of big things like the birth of universe and the death of stars. NPR’s Geoff Brumfiel met one scientist who was chronicling the last moments of a star’s life using sound.

GEOFF BRUMFIEL, BYLINE: Alicia Soderberg works at Harvard University. She says it’s tricky to witness a star’s death.

ALICIA SODERBERG: Because if you want to watch a star die, you have to be in the right place at the right time, and often we’re not. So all we can do is do a stellar autopsy and go back and try to pick up the pieces and figure out what happened.

BRUMFIEL: Soderberg’s autopsy involves collecting every signal she can from the explosions of dying stars: radio waves, light, X-rays. Then she tries to make sense of it.

SODERBERG: The data analysis itself is very detailed.

BRUMFIEL: Now, a few years ago, Soderberg met a graduate student.

WANDA DIAZ-MERCED: Wanda Liz Diaz-Merced.

BRUMFIEL: Diaz-Merced is blind, so she studies astronomy not with sight but by turning data into sound.

DIAZ-MERCED: I have been able to listen, for example, to meteors passing through the atmosphere, solar storms. That is just to give you a gist.

BRUMFIEL: Stars, comets, planets, all sound different.

DIAZ-MERCED: Every sound I listen from the skies, it has its own voice.

BRUMFIEL: Soderberg wondered what all the data from her dying stars might sound like. So she had her team work with Diaz-Merced to translate data points into musical notes. Soderberg says each signal collected as part of her autopsy gets its own place in the orchestra.

SODERBERG: The radio gets the drums, the X-ray gets the harpsichord, and everything in between gets a different instrument, like a violin or a flute.

(SOUNDBITE OF MUSIC)

BRUMFIEL: Listening to these signals together, Soderberg started hearing things – things she hadn’t noticed when she looked at graphs and numbers.

SODERBERG: I hear the data points.

(SOUNDBITE OF MUSIC)

SODERBERG: I hear a very fast crescendo and I hear the sound doesn’t trickle off as slowly as I would expect it to.

(SOUNDBITE OF MUSIC)

SODERBERG: This one, it sounds completely different.

(SOUNDBITE OF MUSIC)

BRUMFIEL: They sound different because the death of every star is different.

SODERBERG: Stars can die by running into each other, for example, like a car crash, or they can die by just running out of fuel. A lot of stars will do interesting things before they die, like pulsate or spin or get overheated.

BRUMFIEL: Each song eerily replays a star’s dying moments as it explodes into a supernova, expands and cools into a cloud of gas and dust.

SODERBERG: It is eerie. At the end of the day, you end up with a supernova remnant. It’s just a nebula of just gas.

BRUMFIEL: But these aren’t only deaths. Supernova explosions release enormous quantities of elements like carbon, oxygen, nitrogen – elements we need. Elements we’re made of.

SODERBERG: I mean, supernovae fertilize the universe. We wouldn’t be here if it wasn’t for supernovae.

BRUMFIEL: In a way, these funeral songs also announce a birth. Geoff Brumfiel, NPR News.

SIEGEL: We’ve posted some of Soderberg’s music along with images of what’s left behind when stars explode. It’s all at our website, npr.org. Transcript provided by NPR, Copyright NPR.

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