Astrophysicists simulate the sounds of stars to reveal their secrets

stars
Credit: CC0 Public Domain

Sound may not be able to travel through the vacuum of space.

But that doesn't stop stars from unleashing a symphony of subsonic notes as their nuclear furnaces power complex vibrations. Telescopes can spot these vibrations as fluctuations in the brightness or temperature on the surface of a star.

Understand these vibrations, and we can learn more about the inner structure of the star that is otherwise hidden from view.

"A cello sounds like a cello because of its size and shape," says Jacqueline Goldstein, a graduate student in the University of Wisconsin–Madison astronomy department. "The vibrations of stars also depend on their size and structure."

In her work, Goldstein studies the connection between and vibrations by developing software that simulates diverse stars and their frequencies. As she compares her simulations to real stars, Goldstein can refine her model and improve how astrophysicists like her peer under the surface of stars by surveying their subtle sounds.

With frequencies repeating on the order of minutes to days, you'd have to speed up stellar vibrations by a thousand or a million times to bring them within the range of human hearing. These reverberations might most accurately be called starquakes after their seismic cousins on Earth. The field of study is called astroseismology.

As stars fuse hydrogen into in their cores, hot plasma gas vibrates and causes stars to flicker. These fluctuations can tell researchers about a star's structure and how it will change as the star ages. Goldstein studies stars that are larger than our own sun.

"Those are the ones that explode and make black holes and neutron stars and all the heavy elements in the universe that form planets and, essentially, new life," says Goldstein. "We want to understand how they work and how they affect the evolution of the universe. So these really big questions."

Working with astronomy professors Rich Townsend and Ellen Zweibel, Goldstein developed a program called GYRE that plugs into the star-simulating program MESA. Using this software, Goldstein constructs models of various kinds of stars to see what their vibrations might look like to astronomers. Then she checks how closely simulation and reality match.

"Since I made my stars, I know what I put inside of them. So when I compare my predicted vibration patterns against observed patterns, if they're the same, then great, the inside of my stars are like the insides of those real stars. If they're different, which is usually the case, that gives us information that we need to improve our simulations and test again," Goldstein says.

Both GYRE and MESA are open source programs, which means that scientists can freely access and modify the code. Each year, some 40 to 50 people attend a MESA summer school at the University of California, Santa Barbara to learn how to use the program and brainstorm improvements. Goldstein and her group benefit from all these users suggesting changes to and fixing errors in both MESA and their own program.

They also get a boost from another group of scientists—planet hunters. Two things can make a star's brightness fluctuate: internal vibrations or a planet passing in front of the star. As the search for exoplanets—planets that orbit stars other than our own—has ramped up, Goldstein has gained access to a trove of new data on stellar fluctuations that are caught up in the same surveys of distant stars.

The latest exoplanet hunter is a telescope named TESS, which launched into orbit last year to survey 200,000 of the brightest, closest stars.

"What TESS is doing is looking at the entire sky," says Goldstein. "So we're going to be able to say for all the we can see in our neighborhood whether or not they're pulsating. If they are, we'll be able to study their pulsations to learn about what's happening beneath the surface."

Goldstein is now developing a new version of GYRE to take advantage of the TESS data. With it, she'll start to simulate this stellar orchestra hundreds of thousands strong.

With these simulations, we might be able to glean a little more about our cosmic neighbors, just by listening in.


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Citation: Astrophysicists simulate the sounds of stars to reveal their secrets (2019, April 27) retrieved 17 July 2019 from https://phys.org/news/2019-04-astrophysicists-simulate-stars-reveal-secrets.html
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Apr 27, 2019
Why is the announcer, Alex Young, talking over the recording of the sun's vibrations the whole time?

Apr 27, 2019
Hmm...so the sun makes cool sounds.
Well, I wonder if the sound of a CME is as follows.
https://www.youtu...ZlEe33Do

Apr 27, 2019
I wish I could have heard more of the cool sounds, instead of Alex Young babbling.

Apr 27, 2019
Note that the bar-line representation of the sound which 'waves' across the video is a COMBINED representation of THREE INPUTS: ie, the *sun* AND *background music* AND *narrator voices* (male voice until 2.23 minutes; then female voice to end of video). A very unscientific/untechnical video representation 'production'. They should have made this clear in the narration; if only to prevent casual misunderstanding of the represented 'bar-line wave' by young/unsuspecting viewers who might assume that is a representation of just the sun component. These 'artistic' treatment' representations/values should be more apparent/clearly pointed out so as to not give wrong impressions of the actual reality phenomena being 'represented' for mass consumption by non-scientists. Leave out the superfluous 'artistic license touches'; because 'less is more' when scientific understanding, rather than 'entertainment', is the aim.

Apr 27, 2019
At least they gave a plug in program a proper name... :-)

Apr 27, 2019
All bodies of Matter/Energy are capable of creating 'sound waves'. Some of them make a whistling, humming, creaking, gurgling and many other noises that are the effects of their chemical and material makeup. The heavy sound of earthquakes in the Earth are caused by the rubbing and crushing together of matter. For some humans, it is audible and often disturbing. The crackle of auroras in the polar regions, as well as that of lightning strikes are sounds made by Matter/Energy. While not exactly musical, the sounds are proof of the dynamic power of the Universe.

Apr 27, 2019
Most people have not heard of Bongard Problems. I think they're one of the best tests of intelligence.

It's part of the Sesame Street curriculum. "One of these things is different from the others, one of these things is not the same."

Home-schooled stupids never saw this. Their parents were afraid of Sesame Street. It taught children how to think, and home-schooled stupids are afraid to think. It might cause them painful cognitive dissonance if they were to learn how.

Apr 27, 2019
Just so the point is driven home, no pain no gain. Reach the Sesame Street lesson no matter how bad it hurts.

Apr 28, 2019
Why is the announcer, Alex Young, talking over the recording of the sun's vibrations the whole time?
says JaxPavan

You're right, Jax. It's a pity that they didn't make 2 separate videos - one for Mr. Young's explanation with the sound bar, and one without him. And RealityCheck is right, that there are 3 inputs until the female voice comes on to end the video. I am surprised that they didn't think to do 2 separate videos. There is way too much distraction from Young's voice to pay enough attention to the sound bar. The music isn't too distracting though.

Apr 28, 2019
Most people have not heard of Bongard Problems. I think they're one of the best tests of intelligence.

It's part of the Sesame Street curriculum. "One of these things is different from the others, one of these things is not the same."

Home-schooled stupids never saw this. Their parents were afraid of Sesame Street. It taught children how to think, and home-schooled stupids are afraid to think. It might cause them painful cognitive dissonance if they were to learn how.

Oh Da Schitts, were you born this stupid or have you been practicing.
https://www.youtu...jQDrDnY8

Apr 28, 2019
So if you're so good, state what the difference is.

Apr 28, 2019
Better yet, try to state what the difference is between these:

https://www.found...pidx.htm

We'll expect an explicit statement for each of the 280 problems shown.

Apr 28, 2019
This Suns Swansong
Why is the announcer, Alex Young, talking over the recording of the sun's vibrations the whole time?
says JaxPavan

You're right, Jax. It's a pity that they didn't make 2 separate videos - one for Mr. Young's explanation with the sound bar, and one without him. And RealityCheck is right, that there are 3 inputs until the female voice comes on to end the video. I am surprised that they didn't think to do 2 separate videos. There is way too much distraction from Young's voice to pay enough attention to the sound bar. The music isn't too distracting though.

A television media vanity failing
wanting to be the centre of attention instead of the subject matter
equivalent to putting ones face in front of the television camera blocking the view
as
in this case their voice over
is
Blocking the suns Swan Song

Apr 28, 2019
This Suns Swansong
A television media vanity failing
wanting to be the centre of attention instead of the subject matter
equivalent to putting ones face in front of the television camera blocking the view
as
in this case their voice over
is
Blocking the suns Swan Song
says granville

I turned the video on again and saw that the sound bar was carrying BOTH Young's voice as well as the sound of the Sun. It is as though Young was competing with the sound coming from the Sun. Surely, he must have eventually come to realise that he was messing up the whole purpose of the video presentation. You can SEE that the sound bar is trying to accommodate both sounds and the lines are jumping around furiously. It is quite disappointing to see that.

Apr 28, 2019
For the Sesame Street exercise, it's red-blue.

Now, don't you feel dumb?

I mean, seriously, it's as plain as the nose on your face. And you're afraid to say it because it might turn out you're wrong.

Apr 29, 2019
The interesting thing about Bongard problems is that when you've spotted the difference you know you're right.

Apr 29, 2019
Why is the announcer, Alex Young, talking over the recording of the sun's vibrations the whole time?


https://www.youtu...zdmg_Dno

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