What dates are accepted for the age of the Sun?

[pavelcherepan]

The whole idea was from the quote:

http://www.scienceforums.net/topic/93429-what-dates-are-accepted-for-the-age-of-the-sun/#entry904859

that said neutrinos will be coming out from the Sun for 170,000 years before the light does, so that might be the early stages of main sequence rather than the T Tauri stage. It wasn't clear in the original quote and backs the purpose of this thread: to work out precisely when the various events occur rather than just saying "when the Sun formed"

The question is did the Sun go through the T Tauri phase?

 

Robbity, first of all, stars in T Tauri stage a proto-star already emits light, even though fusion hasn't started in the core. This is due to contraction heating. In fact, these stars have higher luminosity than what they will have in the future as main sequence stars, because they are simply larger. So you can't say that there are neutrinos coming, but there's no light. There is definitely light and there's solar wind and there might or might not be neutrinos.

 

Secondly, I've said it many times before and I hope you take a note of it this time. Even if there is fusion during T Tauri stage, it's only lithium burning, or pp II chain and there's not much lithium, so the total output of this fusion is probably tiny compared to the heat generated due to contraction.

 

And lastly, yes, based on what we've seen so far, Sun should have gone through T Tauri stage. It seems like it's a normal stage of development for all main sequence stars.

 

 

 

pavelcherepan your doing an excellent job on this thread. I wanted to mention this as astronomy isn't my strongest suit lol.

 

Thanks a lot Mordred. It's not my strongest suit too, but I'm doing my best to try and remember what I had in the uni, because geology curriculum covers a lot on formation of Solar System.

[Robittybob1]

@Pavelcherepan - we are on a similar track now. So this pre-main sequence stage can go on for up to 100 million years.

So it seems that when they say when the sun forms they are talking about events that happened prior to the start of the pre-main sequence phase (PMS), that is up to 100 million years prior to the start of hydrogen fusion. With Lithium burning at the end of this PMS phase.

 

When do you think the first 4 planets formed in our solar system in this time sequence? During the protostar, pre-main sequence or Main sequence stages?

 

....

 

Sun should have been T Tauri-type star in the very early stages of Solar System evolution, some 4.57 bya and it's supposed to have been in that form for some 50 million years or so before finally making it onto the main sequence.

So in your opinion you date the Sun from the time it became a pre main sequence star. The dating of the Sun is based on dating the age of meteorites. They seem to add about 10 million years to the oldest samples found. I don't doubt the dating of the meteorites but how do they know to add time to that date and call it the date of the Sun? Could meteorites be formed before the Sun separated from the protoplanetary disk?

What degree of accuracy has your date got? For you haven't got much time to play with for the stage prior to that was just 1 million years long.

 

Age of the Earth - Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Age_of_the_Earth

The age of the Earth is 4.54 ± 0.05 billion years (4.54 × 10^9 years ± 1%). This dating is based on evidence from radiometric age dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/meteorrbsr.htmlgives a figure of 4.7 billion year for old meteorites. That seems to be well before the age of the Sun in your post.

Do those figures seem right to you?

Edited February 10, 2016 by Robittybob1

[Ophiolite]

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/meteorrbsr.htmlgives a figure of 4.7 billion year for old meteorites. That seems to be well before the age of the Sun in your post.

Do those figures seem right to you?

Doubtless using random, unsubstantiated internet links as a potential source fits in with your random unsubstantiated thoughts. When will you learn to use Google Scholar?

[Strange]

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/meteorrbsr.htmlgives a figure of 4.7 billion year for old meteorites. That seems to be well before the age of the Sun in your post.

Do those figures seem right to you?

 

Thy do not seem right, for the reasons given on that page.

[pavelcherepan]

Radioisotopic dating methods have a margin of error which depends on the time interval measured. At time frames comparable with the age of solar system you are looking at an error margin of some plus or minus 100 million years (maybe a bit smaller).

 

The number I quoted is the best fit of several independent datings of the oldest known inclusion in a chodritic meteorite. Your number seems like it can fall on the far end of the error margin. Where did you get this from?

Edited February 10, 2016 by pavelcherepan

[imatfaal]

Doubtless using random, unsubstantiated internet links as a potential source fits in with your random unsubstantiated thoughts. When will you learn to use Google Scholar?

 

To give Rob his due; Hyperphysics - whilst being no where near the standard of a peer reviewed journal - is a good resource for basic physics (at school level) and run by a practising physics academic (Dr Rod Nave) under the auspices of Georgia State Uni. The data given are referenced as from a pretty standard undergrad/postgrad physics text on the subject. Dr Nave hints at the lack of evidence provided, the unreliability of any firm conclusions (which Rob has missed entirely - and Rob has even managed to choose the less than likely choice), and uses this as a passing lesson in the need for better data sets and invites comments.

 

We must be careful to remain sceptics in these matter - and not become automatically-gainsaying cynics.

[Ophiolite]

You make some excellent points and I stand corrected on the potential value of the linked site. However, in order to retain my sanity and based upon several years of interacting with Rob in another place I shall remain a cynic in regard to his ability to change his spots.

[Robittybob1]

 

Thy do not seem right, for the reasons given on that page.

I did make an unintentional typing error there I'm sorry. I was supposed to say 4.6 rather than the outlier 4.7. I was more concerned not to have hints of speculation in my writing so much so I was distracted from the facts I was trying to say.

Now is the 4.6 billion years the same as 4.57 billion years used in #3 by Pavelcherepan?

[Strange]

Now is the 4.6 billion years the same as 4.57 billion years used in #3 by Pavelcherepan?

 

Given the margin of error (see pavelcherepan's #30) what do you think?

[Robittybob1]

You make some excellent points and I stand corrected on the potential value of the linked site. However, in order to retain my sanity and based upon several years of interacting with Rob in another place I shall remain a cynic in regard to his ability to change his spots.

Call it evolution. You know I always treat your posts with the respect due to them. I can never fully agree with you though for I have been working on this 'alternative' set of hypotheses and if one fails the whole lot fail. Parvelcherepan has introduced an idea in this thread that has stumped me "hopefully not fatally" and that was about the size and brightness of the pre-main sequence Sun being bigger, brighter and hotter than the main sequence Sun. Will I survive?

 

Given the margin of error (see pavelcherepan's #30) what do you think?

I had only woken up during the night concerned I had made a mistake in what I had written just before retiring and I hadn't got back up to Parvel's post yet. But I have now read it and appreciate what Parvel has said but I wonder why the margin of error is not more often discussed along with the date. For example we get told 4.57 billion year but not 4.57 +/- 100 million years. I'd be surprised if there really needs to be such a wide margin of error though.

In #27 http://www.scienceforums.net/topic/93429-what-dates-are-accepted-for-the-age-of-the-sun/page-2#entry905016

The Wikipedia reference gives a 50 million year margin of error i.e. +/- 50 million years, is that what Parvel intended to say?

Edited February 10, 2016 by Robittybob1

[pavelcherepan]

Not hotter. Just brighter. Effective photosphere temperatures of T Tauri stars are about the same as the sun ~5500 K but they are bigger and hence higher luminosity.

 

The more time paseses, the less of daughter isotopes you have and the less of mother isotopes. It gets increasingly harder to measure relationship between those and as a result the error increases exponentially (correct me if I'm wrong ) with the increase of the time period measured.

Edited February 10, 2016 by pavelcherepan

[Robittybob1]

Not hotter. Just brighter. Effective photosphere temperatures of T Tauri stars are about the same as the sun ~5500 K but they are bigger and hence higher luminosity.

 

The more time paseses, the less of daughter isotopes you have and the less of mother isotopes. It gets increasingly harder to measure relationship between those and as a result the error increases exponentially (correct me if I'm wrong ) with the increase of the time period measured.

By "hotter" I mean that to be the effect on neighbouring planets. If the PMS sun is brighter and bigger one study seemed to suggest the inner 2-3 planets would have been too hot for life during the PMS stage. Can you have bigger and brighter without being hotter? Or are you just saying the total amount of light from the larger surface although dimmer (on a watts per square meter basis) will produce more light because of the increased area? That will still make neighbouring planets hotter will it not?

Edited February 10, 2016 by Robittybob1

[pavelcherepan]

Robitty, most of your questions would be easily resolved of you carefully peruse Wikipedia pages on the following topics: evolution of solar system, t tauri stars, radioisotopic dating, evolution of Sun. Please study those carefully and come back with more serious questions.

 

Sorry, can't provide links, I'm on the plane atm.

[Strange]

I wonder why the margin of error is not more often discussed along with the date.

 

I would guess this is because you are getting your information from popular science sites, Wikipedia and other secondary sources. I am fairly certain that if you go to the original research you will find ample detail on the error bounds and sources.

[Robittybob1]

 

I would guess this is because you are getting your information from popular science sites, Wikipedia and other secondary sources. I am fairly certain that if you go to the original research you will find ample detail on the error bounds and sources.

No there are problems of accessing the original papers, then they cover quite a narrow topic in extreme detail. I feel that after a few more years I might be fluent in all the vocabulary they use so that they will have a total meaning.

Wikipedia represents the current state of knowledge. OK the articles can be revised but at least it is all referenced at the end of the article. These sites have the information at the level of complexity that I am able to understand ATM.

I am mostly interested to understand the logic of their arguments.

I am also interested to know what the people on the forum are thinking, like in this discussion what is the event that confirms to you the Sun has formed? At least Pavelcherepan has responded but the rest of you have not said anything.

There seems to be that very important event of the Lithium burning which is one of the most violent events in the Sun's history. I think that is the event that I had been timing events from, i.e. prior to that event or after that event but there is no timing for that event in the general sites. They just say the Sun formed after a million years after the nebula collapse, so without a doubt most events in the Solar system happened after the Sun formed but what were the events that happened between that and the end of the pre-main sequence stage? For that is the stage we are in now, and I think when people think of the Sun forming they think of it as it is now.

I intend to look at scientific papers but I need to understand the basics and the common concepts first.

The other thing that needs more research is the time involved in the clearing of the inner solar system (SS). For it would not be such a clear correlation between the illuminance of the PMS sun and the temperature on the inner SS planets if there was significant dust blocking the radiation.

It would take a considerable time for the dust to clear, and in the meantime dust would scatter light into space. Would planets like Mercury and Venus have been within a habitable zone if that factor was taken into account yet it is not mentioned in this talk on the habitable zones of PMS stars.

 

Thirdly there maybe some value in following up on the possible effect of the Solar Neutrinos. Probably beyond my scope and expertise.

Edited February 10, 2016 by Robittybob1

[Robittybob1]

This science paper discusses and examines the evolution of the dust disk and goes into the physical processes in section 2 "Physical Processes acting on Dust"

http://arxiv.org/pdf/1203.0005.pdf

 

Is that paper peer reviewed? "Dusty Planetary Systems" It seems very logical and well written but what do the experts say?

[imatfaal]

This science paper discusses and examines the evolution of the dust disk and goes into the physical processes in section 2 "Physical Processes acting on Dust"

http://arxiv.org/pdf/1203.0005.pdf

 

Is that paper peer reviewed? "Dusty Planetary Systems" It seems very logical and well written but what do the experts say?

It is a chapter in a book (you will very rarely see a peer reviewed article of that length)

 

Planets, Stars and Stellar Systems. Volume 3: Solar and Stellar Planetary Systems

(Oswalt, T. D., French, L. M., Kalas, P., eds), ISBN 978-94-007-5605-2. Springer Science

 

Firstly it carries the imprimatur of the Editors of the book - and if you want to read through it (I haven't) you might well find that sections of the chapter are lifted straight from Articles with stringent peer review. You might also find in the chapter itself or in introduction or acknowledgements the names of a colleague or two who have read the chapter ( ie I thank so and so for her help and corrections during the writing process - however all errors and omissions which remain are strictly my fault)

 

Secondly - if the publishers are reputable then it is unlikely that the editors of the series or the general editor would allow arrant nonsense

 

FYG most people update their arxiv copies when they are peer-reviewed to show the name / date of the paper publication

[Robittybob1]

Thanks for that analysis.

[Mordred]

Glancing over the article it looks very informative and a good study aid.

[imatfaal]

http://www.amayamoro.com/

 

She seems very well respected for someone still on the track - and has a lovely looking website combined with right-on political views

[Robittybob1]

One of the better images for the day was the picture of B Pictoris. http://www.nasa.gov/sites/default/files/thumbnails/image/hs-2015-06-a-print.jpg

That star is in the main sequence stage and yet is still surrounded by the dust disk. The cross sectional view definitely has the appearance of particles flowing outward rather than inward as was predicted by Poynting-Robertson Drag (PR drag).

 

I feel that even though just about every paper I looked at today mentioned the PR drag none could really explain it fully. Most of the particles some way or another end up in belts of gravitational resonance and stay there until attracted to a planet or become sublimated.

 

These belts of dust definitely could shield a planet as is found in Beta Pictoris. So I still feel that the situation for the planets during the PMS phase, even though the Sun was larger and produced more illuminance the terrestrial planets could quite well have been protected by residual dust from the debris disk and from the abundance of comets in the early stages of the Sun's development, and this was even before the Late Heavy Bombardment (LHB).

Edited February 11, 2016 by Robittybob1

[imatfaal]

from a quick google Poynting Robertson effect is due to asymmetries involving very small particles of dust in orbit about a star.

 

Very simplistically -

From the POV of the particle the sunlight hits it a tiny bit more on its leading side than its trailing side (it is running into the rain) thus there is a tiny loss of angular momentum as the inequality of pressure from radiation provides a net torque against its rotational motion around the star. From the POV of the star the light hits the particle at exactly 90 degrees BUT the re-emission of thermal radiation is stronger in the direction of travel than the reverse and thus the imbalance of photons emitted can be seen as lowering the angular momentum WRTo the star

[Robittybob1]

from a quick google Poynting Robertson effect is due to asymmetries involving very small particles of dust in orbit about a star.

 

Very simplistically -

From the POV of the particle the sunlight hits it a tiny bit more on its leading side than its trailing side (it is running into the rain) thus there is a tiny loss of angular momentum as the inequality of pressure from radiation provides a net torque against its rotational motion around the star. From the POV of the star the light hits the particle at exactly 90 degrees BUT the re-emission of thermal radiation is stronger in the direction of travel than the reverse and thus the imbalance of photons emitted can be seen as lowering the angular momentum WRTo the star

This is what I have been reading all day, paper after paper saying the same thing but when you look at any image of a debris disk the material seems to be clearing in an outward motion rather than in toward the star.

Go back to physics:

So something happens inside the particle to release a photon, why would it have more energy in one direction as opposed to another. Is there some other physics situation that has a similar effect? If it is some quanta of energy say due to an electron orbital change, why would the energy change with direction?

I appreciate the photon will be blueshifted to the forward and redshifted to the rear, but the energy given to that photon must be the same for it is just one event within an atom.

I'm struggling yet no one else seems to.

[imatfaal]

This is what I have been reading all day, paper after paper saying the same thing but when you look at any image of a debris disk the material seems to be clearing in an outward motion rather than in toward the star.

Go back to physics:

So something happens inside the particle to release a photon, why would it have more energy in one direction as opposed to another. Is there some other physics situation that has a similar effect? If it is some quanta of energy say due to an electron orbital change, why would the energy change with direction?

I appreciate the photon will be blueshifted to the forward and redshifted to the rear, but the energy given to that photon must be the same for it is just one event within an atom.

I'm struggling yet no one else seems to.

 

 

Firstly - the effect only applies to particles which are smaller enough to be changed by radiative pressure but not so small that the radiative pressure will blow them away completely (which is what you are seeing (in part) with the dust being cleared). It is a very narrow range of particles.

 

Secondly - you have to look from the frame which stationary with respect to the star. And yes from the frame of the star the radiation re-emitted by the particle is more energetic and carries away more momentum in the direction of travel than in the reverse direction. Remember energy and momentum are related to frequency

 

The best paper I can see to read about it is the heuristic description in Burns, Lamy,and Soter 1979 "Radiation on Small Particles in the Solar System" which is findable by google but I am not going to post a link cos not sure about the validity of the site I found it on

[Robittybob1]

I'll look at that paper today, but last night I drifted off to sleep again thinking about the analogy of a shooter positioned on the back of a speeding truck. If he fires forward the bullet is said to add the muzzle velocity to the speed of the truck, but if he fires to the rear the bullet might have the same muzzle velocity but you have to subtract the speed of the truck to the effective speed of the bullet.

The bullet has different speeds (note I realise light changes frequency rather than speed) but the analogy still holds.

 

Which direction has the most magnitude change in the momentum of the situation?

I'll leave that question with you guys while I read that paper.

 

In your explanation above does the "narrow range" of particles affected by PR drag have no effect on the physical appearance of the clearing of the inner solar system of the debris dust? Pavelcherepan did say the clearing was from the "inside out". I take that to mean the majority of the mass is moving away from the star. Yet PR drag is meant to clear the solar system in the other direction.

 

The article is great and goes into a lot of detail, strangely enough I liked the last sentence of the summary "....until these problems are solved, the life history of a typical member of the interplanetary complex will remain obscure."

This work must have been lost on the majority of the others for they are still on about the P-R effect. It is definitely not a paper I can digest in an hour or two!

 

I was looking for an argument against my concept that the incident photon increased the gravitational potential of the particle. Maybe I was wrong about that .... grrr!

 

If photons produce a drag so will the effects of the neutrinos. I have hunch the physics will be identical yet I was hoping neutrinos to be the mechanism that contributes to the separation of the protoplanetary dust disc from the PMS star. But they seem to be produced too late for the separation has already occurred long before the Lithium fusion occurs.

I wonder what the technical term is used for that separation so I can look it up?

That is a particularly important stage in the Sun's development, it should have a name! Is this the point from which we say "the Sun has formed"?

Is the P-R drag contributing to this separation if so the Sun moves away from the disk faster than the infall of the disk or is the infalling of the disk arrested by radiation pressure so the disc slows and the Sun slips away?

These are just ways I'm trying to understand the physics of the situation - so it might seem childish but truly it is important to understand the cause of this separation.

Edited February 11, 2016 by Robittybob1