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The Spin of a Star Reveals Its Age
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."
The thesis makes a lot of sense. If stars lose mass as they age (stellar winds), that's going to affect their spin. Of course, the tricky part is (a) doing the math and (b) proving it.
!#@%*)anks for hanging up the phone, dear.
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.
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.
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.
You're a freak. Go troll the religious boards, as you obviously know nothing about Science.
That's not even remotely right.
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.
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.
Live today, because you never know what tomorrow brings
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.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
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.
md5sum
d41d8cd98f00b204e9800998ecf8427e
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.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
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 place in science, that is how the big leaps are made. Then they go and check and re check and publish and others do all that all over again.
Science is repeatable. If I can do something, so can you! Not only that but science intermingles. If someone comes up with the wrong idea but don't manage to prove it wrong then other pieces won't fit. Not only are the habits of scientists self-verifying but the science itself is too.
Most importantly if a scientist is wrong they will admit it. There will be whining, some gnashing of teeth, and all the human drama to some degree, but in the end it is either accept the evidence or be shamed out of a career. Truth (of this variety) has a way of becoming pervasive.
Again I ask, because I think this is key: What things specifically do you disagree with outside of those I mentioned? Some examples? Anything other than undirected mistrust?
md5sum
d41d8cd98f00b204e9800998ecf8427e
Because they build a chain of reasoning based on what is actually enormously well-known, mundane physics. We have only known about radioactive decay for just about one hundred years, but at this point we completely understand the process, understand how and why it represents a possible consistent clock, can validate the clock by looking back in time as we look at the light of stars given off in the remote past, and use it routinely to date things like the Earth itself, the fossil record, and the age of the solar system. There are over forty independent radioactive clocks used in radiometric dating, valid for overlapping ranges of dates from billions of years to thousands of years, and where they overlap they by and large agree.
We've known semiconductor physics for just about fifty years (a bit more, but only barely so). How can we feel secure that your computer, built on top of semiconductor physics, will actually work? Yet the physics that describes its operation -- being pure quantum physics involving things like crystal band structure, fermi surfaces, and so on is much more difficult than the physics of blackbody radiation, the fact that the intensity of light drops of like 1/r^2 with distance, and the relationships between power, temperature, and the size of a radiating object. How can we feel "secure" about Maxwell's Equations and the laws of thermodynamics? Because every minute of every day there are a few dozen powers of tens of confirmations of these equations visible to your naked eye, whether or not you know it. If the laws of thermodynamics were egregiously violated, if Maxwell's equations were not classically "true" in the classical limit, if quantum theory ceased to function reliably at the microscopic level, the existing structure of the Universe would catastrophically alter in ways you could hardly miss in the few nanoseconds before your brain chemistry (based on all of these things) ceased to function.
So if your question was intended -- as it seems to be -- to cast doubt on the entire chain of reasoning leading us to believe e.g. that our sun is between 4 and 5 billion years old, that the earth is just a bit younger, so gee -- perhaps the Universe is really only 6007 years old and the Bible is right after all, well, get a grip, you Anonymous Coward you! If it was a genuine question about how "these scientists" in general arrive at sound, reproducible conclusions that represent our best possible state of belief (so far) given the data and the entire network of evidence-supported, consistent beliefs known as "the laws of physics", "the laws of chemistry", etc, well, a good intro book on Astronomy would be happy to answer your questions and Enlighten you. I'd be happy to recommend one. Or you can easily answer your questions using the Internet -- wikipedia contains most of the answers if you start an astronomy wiki-romp and read a few articles on stars, the age of stars, and so on.
The answer to your question is basically that the Hertzsprung-Russell diagram (itself constructed using physics and parallax of the nearer stars) gives us a sound yardstick for Universal distances, one we leverage using e.g. Cepheid variables. Looking back in time (speed of light and distance) and using our knowledge of the fusion process and gravitational process that produces the energy radiated by stars we can make sound inferences about their age, so that the various star types in the HS diagram are themselves also a clock of their relative ages. Given a preexisting clock of stellar ages. "synchronizing" a new clock based on rotational angular momentum of stars of one type or another is straightforward, if tedious.
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Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.