The Spin of a Star Reveals Its Age 67
eldavojohn writes "Some soon-to-be-published research on gyrochronology has yielded a possible method for more accurately determining a star's age. While determining the age of stars in clusters has been done using the patterns of its color and brightness, singular stars are much more difficult. By comparing established age information from clusters and analyzing the spin of stars, the researchers have established a defined relationship between color (mass), spin and age giving them the beginning of a guide of 'stellar clocks.' This was accomplished after four painstaking years of collecting data from 71 single dwarf members of the open cluster NGC6811 and establishing a model using data from Kepler."
How do they know this is remotely valid? (Score:1, Insightful)
Given that astronomy, in its modern form, only goes back a few hundred years at most (and even then, most of the knowledge was obtained within the past century), how can these scientists feel secure measuring events that span billions of years?
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Well, that's the joy of science. You work using models you can't disprove, until they are disproved, then you work under new models.
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Because of lots of hard work, math, observations, and more math. The paper is available in the first link in the summary if you want to read it and come up with legitimate criticisms instead of going with navel-gazing one-liner.
If the technique Meibom et al. have proposed continues to hold up under further observations -- and it looks like there has already been quite a lot of testing -- this will be an awesome tool for astronomers. The age of a star tells you quite a lot, both about the star and about othe
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Good science is testable. Meibom's paper is an example of this. Your post and 36233236 are not; they are nothing more than a bare denial that anything in the universe is knowable. Yours additionally contains several factual errors, which would be more of an issue if the overall thesis wasn't a denial of the potential existence of true knowable facts.
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Good science is testable. Meibom's paper is an example of this. Your post and 36233236 are not; they are nothing more than a bare denial that anything in the universe is knowable. Yours additionally contains several factual errors, which would be more of an issue if the overall thesis wasn't a denial of the potential existence of true knowable facts.
You are still missing the point. Much of what we consider to be "modern" science is still a house of cards which is not built on a known quantity. In the classical scientific method, you have to have a known value that has been verified to be true. Mathematical models are not an adequate replacement for known values derived from direct observation.
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The scientific method is a toy model thrown together by philosophers to attempt what scientists do when they're doing "good science." Very few people in philosophy or science actually subscribe to it. The fact that it's taught as gospel in primary schools is somewhat depressing.
Your other objections are simply not a realistic depiction of modern science or of Meibom's study.
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The scientific method is a toy model thrown together by philosophers to attempt what scientists do when they're doing "good science." Very few people in philosophy or science actually subscribe to it. The fact that it's taught as gospel in primary schools is somewhat depressing.
Your other objections are simply not a realistic depiction of modern science or of Meibom's study.
Really? How fascinating. So what is the name of your science based religion? So you do not "believe" in controls in clinical trials then? Are you sure that you are not confusing philosophy with science?
Re:Observation, not math, is what's important. (Score:5, Insightful)
You are still missing the point. Much of what we consider to be "modern" science is still a house of cards which is not built on a known quantity.
Such as? I can think of string theory (a large unknown with no testable predictions and thus not used for any real science as of yet), dark matter (though we can observe the effects so we know it to be there, they just don't know what it is yet. Lots of very bad theories coming out of this one. I can say that because all but one of them is wrong, and we might not even have the one yet!), and dark energy (which recently got a big boost in observational evidence!)
In the classical scientific method, you have to have a known value that has been verified to be true.
No. Not always. The periodic table of elements was envisioned before there was enough evidence to prove that model correct. Ditto for gravity, "germs", electricity, relativity (general and special), and quantum physics. Those models predicted things that had yet to be observed based on mathematics and known quantities. Their predictions have been tested and proven right. Theories that were wrong are less remembered because they were wrong and abandoned. Steady state, for example.
Mathematical models are not an adequate replacement for known values derived from direct observation.
No, they compliment them. Models predict, observations confirm or contradict. Some models work well only sometimes, like gravity, but within their realm of usefulness they advance science to the point that they break down and science happens all over again. Constant testing and verification. This, just like every other useful model, will be tested mercilessly.
If you think that math and science are strange bedfellows then I encourage you to attempt science without mathematical models. I just don't see how a lack of modeling is an advantage. Clarify if you are willing, but I'm just not seeing it. Mathematics have become more important and much more the focus but it works and it has worked well. Saying that the models don't yield observable quantities nor come from observable quantities is just wrong. Some models take decades. DECADES (I can't stress this enough. Some of Einsteins predictions are still being tested today that have never been tested before such as frame dragging) before their predictions are testable let alone proven.
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Interesting that you should mention string theory. It is a perfect example of philosophy being referred to as "science". The problem with relying heavily on models is that researchers may be unconsciously steering design their experiments and interpreting their data with a bias in favour of their pet model so you end up with a similar phenomenon to how people can see "shapes" in cloud formations. People have a tendency to see patterns in what is chaotic data points.
In a nutshell, the research might be seein
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I even said that string theory is a large unknown. It is most likely bunk. Might not be, but that is not my area of expertise.
You mentioned that the models are "unconsciously" steering their experiments. They aren't. They are 100% fully aware of how the models are steering their experiments. That is how it works. Gotta test the model, how else do you test a model other than devise a test for it?
More importantly that is how plenty of models die. The tests show them to be wrong. Creativity certainly has its p
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+5
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Mathematical models are not an adequate replacement for known values derived from direct observation.
I think you have misunderstood the last 500yrs science, mathematical models are not supposed to be a replacement for observations, they are a way to predict observations because you cannot observe what has not happened yet. No amount of past observations or scientific theory can give you a 100% guarantee about anything, if you want that kind of dogmatic certainty join a church.
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You're a freak. Go troll the religious boards, as you obviously know nothing about Science.
Re:Calculations are not direct observations. (Score:5, Insightful)
Here's how science works (as it applies to astronomy):
- You form a hypothesis. In the case of astronomy this would most likely be a concrete mathematical model.
- Your model has predictions which you test.
- If the predictions are valid you look for more ways of testing the model. If not, you scratch it.
Observing the creation and death of one star is *not* necessary to test these models. There are an astronomical(!) number of stars to observe. You have plenty of stars in different stages of development to test the model with.
Certainly the model could be wrong, even if the data are consistent with it, but that does not make it unscientific.
Re:Observation, not math, is what's important. (Score:4, Insightful)
Age can be measured as a consequence of physical behaviour of stars. The difficulty is only knowing exactly which quantities to combine to get the best estimate.
I won't comment on your other ignorant claim that we can't witness the birth of stars today.
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Re:How do they know this is remotely valid? (Score:5, Insightful)
If you took photos of billions of people - but only one per person - could you get a decent idea of how humans age? Same with stars there's roughly 10,000,000,000,000,000,000,000 of them and there's many in every phase of life even though we pretty much only see a snapshot of each one. Take supernovas for example, a very short and rare event we haven't seen since 1604 in the Milky Way even though it has 200-400 billion stars. And yet we find 2-500 of them each year because there's so insanely many galaxies to look at. We won't have observed one star birth to death, but we will have observed everything from baby stars to stars in death throes many, many times.
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Shall i risk the obligatory comparison?
If i had a car...
No.
How about: Evolutionary biology has only been around for 150 years, how can these scientists feel secure measuri
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Evolutionary biology has only been around for 150 years, how can these scientists feel secure measuring events that span millions of years?
While I don't know the AC who made this particular anti-science rant, I would imagine the typical response to this would be "Yes! See? Evolution is wrong!"
The underlying issues is a lack of understanding and confidence in science. The only way I know of to deal with the lack of confidence is to work on the understanding.
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So how many years does a science need to be around before you feel secure in its ability to measure events that span millions of years? 200 years? 500 years? 1000 years? 10,000 years?
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Given that astronomy, in its modern form, only goes back a few hundred years at most (and even then, most of the knowledge was obtained within the past century), how can these scientists feel secure measuring events that span billions of years?
Light, for example, is the same, no matter what the age of the source or how long it took to get to Earth. They aren't measuring events that spanned billions of years, they're measuring things like light. The interpretation follows very sound observations.
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Seems commonsense in retrospect. (Score:3)
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That makes sense if you know the stars initial spin. I'm curious how that is known.
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Also, http://en.wikipedia.org/wiki/Stellar_rotation#Measurement [wikipedia.org]
you forgot the "checkmate"
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Well that has nothing at all to do with my question, but thanks for trying.
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like how many candles were on their cakes ?
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Possibly as interestingly, is initial spin constant across all stars? All types of stars?
Still potentially interesting research.
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Re:Seems commonsense in retrospect. (Score:4, Funny)
That makes sense if you know the stars initial spin. I'm curious how that is known.
Well, in the case of Madonna, we were able to look at her early videos. Based on this, we calculated her age as 1.1873 x 10^16 years.
[insert Big Bang joke here]
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Imagine the readings they must get from Zsa Zsa Gabor.
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I suppose that might be funny, but TFA tells us that stars' spin decreases with age.
Perhaps his supermassive ego is significant and your post is actually hilarious, but I always took Sheen for a big-headed, yet vacuous twit.
Excellent. Now go repeat with another cluster (Score:2)
...otherwise how do you know the relationship holds true outside of that one cluster. Perhaps there was something special about the conditions in which that cluster formed. These people aren't amateurs and probably have good reason to believe these relationships hold true elsewhere, but since we're talking science, credentials mean squat and it should be repeated.
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Can it see through plastic surgery? (Score:2)
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Where is the angular momentum going? (Score:2)
I'm happy enough with the idea that a star's mass determines its initial angular momentum (or, more likely, vice versa.) While not obviously true, it is certainly plausible. But once its angular momentum is set, how can it slow down? Here are all the possibilities I can think of:
* It expands (radius increases) and so it can spin slower for the same angular momentum. However, this would be very uninteresting - if we have luminosity and temperature, we already know the radius. Adding an extra measurement whic
Re:Where is the angular momentum going? (Score:4, Informative)
OK, I've done some cursory research (abstracts and intros of a few papers.) I didn't find a review, however it seems that there has been quite a bit written about such angular momentum transfers, and the age-rotational period-mass relationship for stars. (So this result is a step in an already developed field, not a breakthrough.)
There was mention of interactions with a magnetized solar wind (i.e. a combination of my points 3 and 4 above) and also something called the Tayler-Spruit dynamo, which I think is about angular momentum transport between the star's core and envelope. For a young star, you'd expect the core to rotate faster than the envelope (conservation of angular momentum during the contraction) but the sun rotates like a solid body - same rotation period for all depths (or as far as we can probe by helioseismology.) The Tayler-Spruit appears to be a possible explanation for how a middle aged star like the sun can rotate like a solid body.
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cool, thanks for the extra info.
I read the article to understand ... (Score:2)
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