Looking for Reference Thread Ideas

Saiph · Sep 10, 2005

I used to have several large "reference" threads on the boards before the crash (over a year ago). Pretty shortly, I'm not going to have time to even think about this again, so I thought I'd work on one or two now. Anybody have any requests/ideas on general astronomy topics they'd like to see addressed? Also, if anybody wants to write a reference thread, or add to mine, feel free. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Sep 13, 2005

Saiph - Hi! A few questions I would like researched further: 1. Was that antimatter (annihilation) jet from the Milky Way confirmed? 2. To what extent will earth's orbit recede from the sun as the sun loses mass as it approaches red giant phase? 3. Do the floating magnetic fields within the sun actually travel from core to surface? Does the magnetic dynamo heating the solar corona have its ultimate source near the core of the sun? 4. If so, to what extent might this cause mixing of hydrogen depleted (somewhat) core content with hydrogen rich outer layers? 5. What would reasonable limits be for how much longer it would then take our sun, whose magnetic field properties may be quite unique, to reach red giant phase - and the resulting greater loss of solar mass would cause earth's orbit to recede how much further? Saiph - thats just a few of my many questions - I will post again. BTW - I have a new computer - my absence was in part due to a fried modem (lightning) Hope you are well. How are your studies going?

yevaud · Sep 13, 2005

Odd you said that, as I just promised a few days ago to do a small tutorial on weather, climate, and remote sensing. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Sep 13, 2005

well, really quick answers for you: 1) Don't know actually. 2) Not sure, probably not a big effect. I can do a quick calculation in a bit. My guess: not more than a 10% shift (I think the shift is proportional and I think the sun will lose ~10% of it's mass due to fusion...or is that 10% of the core mass....). 3) Ahh...no clue. i'm not sure anybody knows for sure if the fields go all the way down. There are likely fields there, but I don't know how coherent they'd be. 4) Not very. there are some major convective events called "dredge ups" in a stars evolution that likely help a bit...but they are accounted for as best we can. they don't extend the life of a star to much. 5) By the time the sun losses more mass by bieng in the red giant phase, it's already to late for us. An increase in the sun's luminosity by any significant amount would be very...unhealthy. I am well, and my studies as a graduate student begin in a couple of weeks. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Sep 13, 2005

1 - I'll re-research that. 2. Most of the core is supposed to fuse from hydrogen to helium - with some loss of mass ... Note that our sun may be unique. It is now known that stars vary drastically in their magnetic fields, which is why a few become magnetars. Your answer is correct for stars in general - however, "star differs from star in glory." 3. Well, there are models based on observation that postulates that floating magnetic fields do travel from core to solar surface. 4. Again, that is the standard model for the average main sequence star. 5. Some models do have our earth receeding from the sun quite a bit in orbit - I do remember linking to some of these variant models which presented math evidence. Yes, if our sun is not fined tuned for our survival, and if it is not fine tuned for our survival in the future, we would be in servious trouble. If, however, is a BIG word!

newtonian · Sep 13, 2005

A few more questions: 6. Why is the intergalactic medium hotter in recent billions of years? Supernovas? Magnetic sources? - The medium is highly ionized or magnetized. 7. How much energy was incorporated (in my belief - by God) into the singularity to cause the big bang? Has anyone attempted a math calculation based on e=mc^2 for the origin value for e in the origin of our universe? 8. How could the laws and fine tuned properties of our universe be created? E.g.: the rations of the 4 forces of physics that allow life as we know it to exist in our universe? Or the rate of expansion - now complicated by acceleration of expansion? 9. How did life’s molecules become chiral, rather than racemic? E.g. - why are proteins almost exclusively left hand polarized (L-amino acids)? 10. How did sugars, fats and polypeptides polymerize towards life when they normally inter-react with each other and end pathways towards life’s complex molecules by interfering cross reactions? 11. We have global warming. Is solar output increasing? Is it due mostly to the greenhouse effect? (I suspect it is). 12. What is the current average percentage of depletion of ozone protection from solar radiation in temperate zones? Beware of skin cancer, btw. 13. How did earth get its water? My favored model involves catastrophes rather than a smooth uniformitarian transition. I suspect condensation catastrophes due to earth's crust cooling complicated by accretion of water through gravity vs. orbital velocity. 14. How much water could have been in earth's La Grange points in the early earth history? What may have propelled water towards earth? Comets? Meteorites? To what extent may water have been produced chemically - e.g. by photolysis of oxygen containing compounds bonding to existing hydrogen to produce water? Or photosynthesis producing fre

Saiph · Sep 13, 2005

First, if you state our star is special, everything goes out the window. Especially if you don't have any evidence. Second: by all observations, our sun is a typical G2 V star. As such, all the trends, lifecycles, and effects we see in a G2 V class star can only be expected to apply to our sun. If you claim that magnetic fields can vary alot between stars, even of the same type, thats fine. Except these trends are defined by thousands of stars, so they take into consideration such differences. This creates a spread in the trend, but the trend is still there. the sun can only be expected to fall somewhere within the range of that trend. Unless it's very "special" which I haven't seen any evidence for. Even if the sun loses 50% of it's mass before blowing up, our orbit would shift by 50% to 1.5 Au...still way to close to a red giant star. We'd cook. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

vogon13 · Sep 14, 2005

Just curious, is our sun rather old ( ~4 1/2 billion, give or take) for a star as metal rich as it is? <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

Saiph · Sep 14, 2005

6) not familiar with this. 7) good question, I'll see what I can dig up. 8) this is the antropic principle arguement. My counter is: If the laws were any different, we'd be different and be perfectly able to ask the exact same question of these new, different laws. Or we wouldn't be around to ask. You can ask that from any frame in which a thinking being exists. Finding out why the laws are what they are (e.g. if gravity affects how EM forces work etc) is neat. but "fine tuning" is a human-centric point of view that I don't like. a lot of the rest is chemistry. A note on global warming: during the 70s and 80s it was commonly professed to the be sun causing it, and the sun may have a significant effect yet. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Sep 14, 2005

Saiph - Thank you for your responses. Agreed that we have much to learn. However, continued studies confirm variations in magnetic fields in various stars, along with other variations among stars that are or were main sequence stars. As per my reference to magnetars. To really determine if our sun is average for its type, we would have to know the properties of other stellar coronas for this type star for comparison purposes. Do we have this data yet? Could you please explain what a G2 V star is?

newtonian · Sep 14, 2005

Saiph - on #8 - I don't like philosophy either - I was really inquiring as to cause and effect. What scientific mechanism could cause laws to come to exist? On fine tuning - some fine tuned factors would not even allow heavier elements to exist, let alone life as we know it. I agree there are other forms of life which do not require these fine tuned parameters - e.g. God, angels. I don't see this as a human centric point of view - The ratios and properties existed long before humans existed - all we do is scientifically discover these things. I do find the various factors required for life as we know it to be amazing and humbling.

newtonian · Sep 14, 2005

vogon 13 - I'll have to research that. The sun contains about 2% heavier elements, so its creation involved material from stars which already created these heavier elements. Saiph - G2 I got, it is the spectral class of our sun. It is the Harvard classification which has the following for hot stars, in decreasing temperature order: O, B, A, F, G, K, M. The 2 after G is also in order of decreasing temperature, from 0 to 9. This has little to do with magnetic fields. What of the V?

yevaud · Sep 14, 2005

The V denotes that the star is located on the Main sequence, as opposed to being a dwarf star or giant. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

newtonian · Sep 14, 2005

Yevaud - Thank you. Why V? I know R, N, S are for cool stars, and that W is for the very hot Wolf-Rayet stars. That leaves T, U, V....

yevaud · Sep 14, 2005

http://www.ngcic.org/papers/gctext.htm This might help. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

raghara2 · Sep 14, 2005

9 keying. When majority has some orientation it decreased probability of apearing to the other type. 13 Evaporation from core, and stuff. You know it was more than one way. I would rather formulate this question. How did was the water dissalowed to split on O + H and evaporate from the planet? (Gravity, distance from sun, water vapor trap, electromagnetic field, and volume of water would be answer.) Water isn't something scarce. You can have planet covered with 100 km oceans. You can also have planet covered by ice, and have another ice few tenths of km under water. I think if mercur would switch with mars it could have also significant amount of water (if it would be without close moons.)

newtonian · Sep 15, 2005

ragharA2 - 9. You have some basis for that conclusion? How did a majority have the L configuration? Consider, for example, the many origin of life synthesis experiments starting with Miller's famous 1950 scenario. Are you familiar with the actual experimental results? To add to my question, what are some details concerning optical isomers of amino acids found on meteorites? 13 Good point - often overlooked. H2O does indeed split to H2 and O under ultraviolet light, which is called photolysis. This would have been a major source of free oxygen on earth before life began - perhaps .1% or 1%. And that causes problems with popular chemical evolution scenarios which assume near zero oxygen. Was photolysis stopped during the origin of life. That is indicated in the Biblical model in Genesis, where whatever God's spirit was doing (perhaps creation life) in Genesis 1:2 was before light had penetrated to earth's surface. Therefore no surface photolysis and little surface free oxygen but plenty of water.

newtonian · Sep 15, 2005

Yevaud - Thank you for that excellent link. I need time to study that before responding.

newtonian · Sep 18, 2005

Yevaud - while that link is very informative and I appreciate your sharing it - it does not help determine what saiph meant by V - it does not use V for Main Sequence but rather for Visual portion of spectrum. Here are a few notes on that appreciated link: OK, studied the link - and I will keep the info for reference as it lists so many stars in globular clusters.. First, on that GV2 classification for our sun: 1. Listed are V magnitudes according to the 1992 classification from “Integrated Photometric Properties of Globular Clusters “ by C. J. Peterson, 1993 from a conference paper entitled Structure and Dynamics of Globular clusters. Note that this classification is based on magnitude, not magnetic properties. 2. The link also references B-V colour. 3. The link attempts a diagram that gives observational support for the well-known Herzsprung-Russell diagram which plots the luminosity of stars against the temperature of stars. Since we do not know directly the actual brightness and temperature of stars, the link documents: A. The apparent brightness of a star. B. The colour of a star as a function of the difference in brightness of a star in two wavelengths (in the spectrum), namely: the blue end of the spectrum and the red end of the spectrum. The apparent brightness is the visual, hence the V for visual. The brightness (B for blue -V for brightness function), i.e. the B-V (B minus V) colour, is calculated as a numeric value. The general result, ignoring complicating factors, is that stars brighter in the blue end of the spectrum are hotter while stars brighter in the red end of the spectrum are cooler. Picking the blue end and comparing it with the overall brightness, in the UBV system (this system, I have no idea what U stands for) one gets numeric values with approximately correspond with star temperature. Vega,

Saiph · Sep 19, 2005

In spectral classifications you have the temperature indication which is a letter from this set: OBAFGKM (R,S&T are occasionally included). The number is a gradation between the letters. So a G5 is halfway between G and K. The roman numerals following the spectral classification indentify which luminosity class the star belongs to (it's the "Yerkes Luminosity Class" IIRC). These are commonly labeled as such: Ia Very luminous supergiants Ib Less luminous supergiants II Luminous giants III Giants IV Subgiants V Main sequence VI Subdwarf VII White Dwarf This sub-classification is required because an M class star can be really dim (a red dwarf star) or very, very bright (a red supergiant) despite having the same color, temperature and spectral lines present. One way to distinguish between these classes is the specific attributes of the spectral lines. All M1 stars share the same lines, in the same strengths. However, type 1a stars have narrower lines than type V as the high pressure environment of a type V (relative to a type Ia) broadens the lines due to collisional broadening. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Sep 19, 2005

Saiph - thank you. I knew visual didn't fit! Another question - Here's a quote first, speaking of the studies of star spectra: "The spectrum requires careful interpretation, but can yield a great deal of information about such factors as temperature, chemical compostion, density, rotation rate, and the presence of magnetic fields." - "The World of science, Volume 8, "TRhe Universe," page 32. Alas, the source does not add detail. How does spectral analysis yield information about stellar magnetic fields, and what have we learned from these studies about stellar magnetic fields compared with our sun's magnetic fields??

Saiph · Sep 19, 2005

Spectral lines are created by the electrons transitioning from one quantum state to the next. One of the defining quantum characteristics of a state is the "magnetic quantum number". However, this is only manifested, or measurable, when a magnetic field is present (otherwise the possible values for the magnetic state are indistinguishable). And the stronger the magnetic field, the more pronounced these minor quantum states are. Zeeman splitting is common manifestation of magnetic fields in spectral lines (and how we know sunspots are areas of high magnetic fields). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Sep 19, 2005

Saiph - Thank you. I had never heard of Zeeman splitting! So, what do we learn about other stellar magnetic fields - i.e. is there an average and extremes? I know there must be extremes, as some stars evolve into magnetars.

Saiph · Sep 19, 2005

Well, from what I recall, most stars appear to be like our sun. Strong, but nothing really unusual. I don't remember much about it really (and it isn't covered much in lower level classes, magnetic fields are hard) <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

yevaud · Sep 20, 2005

Crud. I gave you the wrong link. The one I had was a very good discussion of the HR diagram, the various classes of stars, and how/where they place. *Sorry* <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

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