Astronomers detect echoes from the depth of a red giant star

Mar 18, 2011
Credit: SAp/CEA

(PhysOrg.com) -- Today an international team of astronomers reports the discovery of waves inside a star that travel so deep that they reach the core. The discovery was published in the renowned journal Science, and was possible thanks to precise measurements with the Kepler space telescope.

Waves traversing stars, similar to sound waves here on Earth, were already known to exist, but up to now only waves in the outer part of the star were observed. They travel hundred thousands of kilometers deep, and at a certain depth the stellar material gets too dense to penetrate so that the waves bounce back to the surface. The team now unexpectedly found the signature of waves that run all the way to the center of the star.

Astronomers love this kind of waves, or stellar oscillations as they call them. Just like a doctor listens to the sound of your heart to make a diagnosis, or like seismologists use earthquakes on Earth to probe the inside of our planet, the scientific discipline of asteroseismology studies stellar oscillations to draw a detailed picture of stellar interiors. The detection of waves that are able to “sense” the conditions in the core of a star opens a window to an inferno which otherwise would remain unreachable and hidden.

The discovery was made in a red giant star. These are elderly stars which our Sun will become in about 5 billion years. By that time our Sun will have inflated more than 10 times its current size, and will be about 50 times brighter. At the same time its color will have changed from yellowish to reddish, hence their name.

“Having a view into the core of these will teach us exactly what will happen to our Sun when it grows older.”, says Paul Beck, a PhD student at Leuven University in Belgium. Paul is one of the many young researchers that are given the opportunity to work with Kepler data. He, Tim Bedding of The University of Sydney, and Marc-Antoine Dupret from the University of Liège were the first to notice that some oscillations seemed to behave differently, “out of key”. After comparing the observations with theoretical models, they soon realized that they were looking at waves that feel the conditions in the heart of the star.

At the starʼs surface the oscillations manifest themselves as patches where the temperature changes slightly, more or less periodically over time. Overall, this causes tiny variations in the brightness the star, and after the light traveled for hundreds of years through empty space these changes are now carefully recorded by NASAʼs Kepler.

The team that made the discovery is part of KASC, the Kepler Asteroseismic Science Consortium, currently one of the largest consortia in astronomy, consisting of more than 440 astronomers specialized in probing stellar interiors. Its headquarters are located in Aarhus, Denmark. “Astronomers of all over the world are taking part in this huge effort to exploit Kepler data to better understand the interiors of stars”, says Hans Kjeldsen of Aarhus university, the coordinator of KASC. “The measurements provided by Kepler are so incredibly precise that we see things we never saw before. Itʼs like traveling in a whole new world.”

The spacecraft is expected to operate for at least another 2 years, and will continue to measure the same stars, making the datasets better every day. For sure to be continued.

Explore further: Astronomer confirms a new "Super-Earth" planet

More information: Kepler-Detected Gravity-Mode Period Spacings in a Red Giant Star, Science, DOI:10.1126/science.1201939

Provided by Leuven university

4.4 /5 (7 votes)

Related Stories

Kepler spacecraft takes pulse of distant stars

Oct 26, 2010

(PhysOrg.com) -- An international cadre of scientists that used data from NASA's Kepler spacecraft announced Tuesday the detection of stellar oscillations, or "starquakes," that yield new insights about the size, age and ...

Listening to other stars

Feb 15, 2010

When scientists realised that observing and analysing oscillations in the Sun could provide information about its interior, it was only a matter of time before Helioseismology was put to work on other stars.

Allo, allo? A star is ringing

Dec 21, 2005

Astronomers have used ESO's Very Large Telescope in Chile and the Anglo-Australian Telescope in eastern Australia as a 'stellar stethoscope' to listen to the internal rumblings of a nearby star. The data collected ...

Recommended for you

Kepler proves it can still find planets

Dec 18, 2014

To paraphrase Mark Twain, the report of the Kepler spacecraft's death was greatly exaggerated. Despite a malfunction that ended its primary mission in May 2013, Kepler is still alive and working. The evidence ...

User comments : 23

Adjust slider to filter visible comments by rank

Display comments: newest first

Nik_2213
5 / 5 (16) Mar 18, 2011
No neutron-star core within ? How inconvenient for several outré hypotheses...
Calenur
5 / 5 (12) Mar 18, 2011
No neutron-star core within ? How inconvenient for several outré hypotheses...


Oh Snap.
omatumr
1.1 / 5 (18) Mar 18, 2011
Yes, "this kind of waves, or stellar oscillations as they (astronomers) call them" contain information on the interior of stars. Do they cite the following?

P. Toth,"Is the Sun a pulsar?" Nature 270 (1977) 159 - 160

www.nature.com/na...9a0.html

C. A. Rouse, "Evidence for a small, high-Z, iron-like solar core," Astronomy & Astrophysics, 149 (1985) 65-72.

O. Manuel, "Isotope ratios in Jupiter confirm intra-solar diffusion", Meteoritics & Planetary Science 33, A97 (1998) 5011.

D. V. Reames, "Abundances of trans-iron elements in solar energetic particle events," The Astrophysical Journal 540 (2000) L111 - L114.

epact2.gsfc.nasa.gov/don/00HiZ.pdf

O. Manuel, C. Bolon and P. Jangam, "The sun's origin, composition and source of energy," Lunar & Planetary Science, vol. XXIX (2001) 1041.

www.omatumr.com/lpsc.prn.pdf

O. Manuel, "Neutron Repulsion," The APEIRON Journal (2011) in press.

arxiv.org/pdf/1102.1499v1
omatumr
1.8 / 5 (20) Mar 18, 2011
The last sentence in the report is the most important one:

"For sure to be continued."

Here's a link to "Isotope ratios in Jupiter confirm intra-solar diffusion", Meteoritics & Planetary Science 33, A97 (1998) 5011.

www.lpi.usra.edu/...5011.pdf

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
Zephyr311
2.1 / 5 (20) Mar 18, 2011
Oliver Manuel, you seem to have a silent stalker who simply ranks whatever you post at "1". I'm starting to think this site is a waste in terms of discussion and insights. Thank you for (a) engaging in discussion and backing up your ideas and (b) doing it civilly.
Bonkers
4.4 / 5 (7) Mar 18, 2011
Yes, I'll second that. Your post is entirely on-topic, well referenced and civil.
barakn
5 / 5 (10) Mar 18, 2011
Oliver Manuel, you seem to have a silent stalker who simply ranks whatever you post at "1". I'm starting to think this site is a waste in terms of discussion and insights. Thank you for (a) engaging in discussion and backing up your ideas and (b) doing it civilly.

You must not be referring to me, as I'll give omatumor 5s for posts that warrant it. I'm also not silent. In fact when Omatumor recently repeated his claim (for the hundredth time) about isotope ratios in Jupiter, I pointed out that a more careful analysis of the data directly contradicted him (see the last March 4th comment in www.physorg.com/n...ain.html ). If omatumor was actually interested in "engaging in discussion and backing up [his] ideas," he would have responded.
omatumr
1 / 5 (6) Mar 18, 2011
Exactly what evidence, barakn, do you have that disagrees with:

a.) The experimental data released by the NASA Administrator, Dr. Dan Goldin, in response to my question to him in January 1998, and

b.) The analysis that concludes the Galileo probe found following evidence for "strange xenon" in Jupiter, with

(Xe-136)/(Xe-134) = 1.04 +/- 0.06

www.omatumr.com/D...Data.htm

By comparison, (Xe-136)/(Xe-13 4) ~ 0.80 in the solar wind that pours from the top of the Sun's atmosphere, and

(Xe-136)/(Xe-13 4) ~ 1.04 in the "strange xenon" found to accompany all primordial He at the birth of the solar system.

"Elemental and isotopic inhomogeneities in noble gases:
The case for local synthesis of the chemical elements",
Transactions Missouri Academy Sciences 9, 104-122 (1975).

"Strange xenon, extinct super-heavy elements, and
the solar neutrino puzzle", Science 195, 208-209 (1977).

"Solar abundances of the elements",
Meteoritics 18, 209-222 (1983), etc.


omatumr
1 / 5 (8) Mar 18, 2011
Oliver Manuel, you seem to have a silent stalker who simply ranks whatever you post at "1". I'm starting to think this site is a waste in terms of discussion and insights. Thank you for (a) engaging in discussion and backing up your ideas and (b) doing it civilly.


Thank you for your message and for noticing efforts to distract the discussion away from science.

Please let me know if you need directions to a separate Yahoo discussion group on "Neutron Repulsion"
Skeptic_Heretic
4.4 / 5 (13) Mar 18, 2011
Please let me know if you need directions to a separate Yahoo discussion group on "Neutron Repulsion"
Go through to "cryptozoology", take a left at "the evidence of a creator", and take a right at "9/11 conspiracy proofs".
MorituriMax
1 / 5 (1) Mar 18, 2011
Hmmm, maybe its the AT&T Guy going, "Can You Hear Me Now?"
geokstr
2.2 / 5 (17) Mar 19, 2011
...take a right at "9/11 conspiracy proofs".

Sorry, you need to take a LEFT turn to get to 9/11 conspiracy proofs.
barakn
4.3 / 5 (6) Mar 22, 2011
Omatumr, since it apparently went unnoticed in the previous thread, here is the definitive paper on Galileo probe mass spec data:

Mahaffy, P.R., H. B. Niemann, A. Alpert, S. K.Atreya, J. Demick, T. M. Donahue, D. N. Harpold, and T. C. Owen, Noble Gas Abundance and Isotope Ratios in the Atmosphere of Jupiter from the Galileo Probe Mass Spectrometer, JGR Planets 105, 15061 - 15071 (2000)

www-personal.umich.edu/~atreya/Articles/2000_Noble_Gas.pdf

Despite your devotion to the data from Dr. Goldin, Mahaffy et al were the ones that took a mass spectrometer virtually identical to the one on the Galileo spacecraft and calibrated it by subjecting it to the same pressure and temperature regime experienced by the Galileo probe's mass spec as it plunged into the Jovian atmosphere.

This more careful analysis shows a lower value of (Xe-136)/(Xe-134) = 0.84 +- 1.54
Two things of note here, the approximately solar value of .84 and the huge uncertainty estimate.
omatumr
1.4 / 5 (9) Mar 22, 2011
Quite obviously theirs was not "the more careful analysis."

(Xe-136)/(Xe-134) = 0.84 +/- 1.54

DOES NOT DISAGREE WITH

(Xe-136)/(Xe-134) = 1.04 +/- 0.06
barakn
4.4 / 5 (7) Mar 22, 2011
Quite obviously theirs was not "the more careful analysis."
That's the kind of rooky assumption I'd expect from a high school student. The fact that Mahaffy et al, after starting out with the same data as Goldin but incorporating a more painstaking calibration, came up with a larger uncertainty indicates that they more carefully considered all the possible sources of error.
omatumr
1 / 5 (5) Mar 22, 2011
Quite obviously theirs was not "the more careful analysis."
That's the kind of rooky assumption I'd expect from a high school student.


Not at all. It appears that you have not analyzed isotope data or had any experience with error propagation in the process of data reduction.

barakn
5 / 5 (4) Mar 24, 2011
Two students in a lab are measuring the square area of a computer chip using a ruler. Since the smallest units on the ruler are millimeters, they conclude they are limited to a measurement resolution of half a millimeter. They measure 24.0 mm x 32.0 mm = 768 mm^2. The uncertainty (assuming the two measurements are independent of each other) is 768 mm^2 * ((.5/32)^2 + (.5/24)^2)^(1/2) = 20 mm^2 (bonus points for identifying which rule I used at en.wikipedia.org/wiki/Uncertainty_propagation)

Then the lab instructor proclaims that she played a trick on them. The chips were baked at too high a temperature and on a slight incline due to an improperly positioned rack during an annealing step. The chips are not perfectly rectangular, they are parallelograms.
barakn
5 / 5 (4) Mar 24, 2011
Using the ruler, a protractor, some tracing paper and a pencil the students measure one of the corners as being 85 degrees, but due to the large size of the protractor relative to the chip, they are only confident in their measurement to within +- 4 degrees. They plan on using a formula for a parallelogram of Area = AB sin(x) where A and B are the lengths of two sides and x is the angle of the corner between those two sides. If y = sin(x) and dx is the error in measuring x, the error in y - we'll call it dy - can be found by taking the derivative of both sides: dy = d(sin(x)) = cos(x) dx. In our case dy = cos(84 deg) * 4 degrees. We'll have to be careful here because the answer only makes sense using radians, not degrees. dy = cos(84 degrees) * 4pi/180 = 0.00730. We know AB and it's uncertainty from before, so the area is 768 mm^2 * sin(84 deg) = 764 mm^2. The uncertainty is 764 mm^2 * ((20/768)^2 + (.00730/sin(84 deg))^2)^(1/2)= 21 mm^2.
barakn
5 / 5 (6) Mar 24, 2011
The error has increased from 20 to 21 mm^2. So here we have a concrete example of how more careful analysis - using error propagation - leads to greater uncertainty, despite Omatumr's assertion that it can only lead to less. And yes Omatumr, I have analyzed isotope data. I used to work with tritium quite a lot.
omatumr
1 / 5 (5) Mar 24, 2011
The Sun exploded ~5 Gyr ago and gave birth to the Solar System, as first suggested in 1975:

"Elemental and isotopic inhomogeneities in noble gases: The case for local synthesis of the chemical elements", Trans. Missouri Acad. Sci. 9, 104 122 (1975)

"Strange xenon, extinct superheavy elements and the solar neutrino puzzle", Science 195, 208-209 (1977)

"Isotopes of tellurium, xenon and krypton in the Allende meteorite retain record of nucleosynthesis", Nature 277, 615-620 (1979)

"Heterogeneity of isotopic and elemental compositions in meteorites: Evidence of local synthesis of the elements ", Geokhimiya (12) 1776-1801 (1981)

" Solar abundance of the elements", Meteoritics 18, 209-222 (1983)

That is why He-rich carbonaceous inclusions of meteorites (diamonds) and in Jupiter's He-rich atmosphere both have:

(Xe-136)/(Xe-134) = 1.04 +/- 0.06

With kind regards,
Oliver K. Manuel

omatumr
1 / 5 (3) Mar 25, 2011
And yes Omatumr, I have analyzed isotope data.


Your comments suggest otherwise.

If you have in fact published any of your analysis of isotope data, please post a complete reference to those/that paper.

barakn
4.2 / 5 (5) Mar 25, 2011
Nah. Why don't you read the Mahaffy paper and produce a point-by-point analysis of what's wrong with it or how their methods were inferior to the Goldin data?
omatumr
1 / 5 (4) Mar 25, 2011
Nah.


Thanks for confirming what I long suspected: All fluff, no substance.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.