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#1
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Mystery of the hidden cosmos.
In Scientific American of July 2015 there is an article with the title:
"Mystery of the hidden cosmos." The article starts with sentences like: "The speed of its rotation cannot be explained by applying the laws of physics to the disk's visible matter." and "If the visible matter was all there was. Andromeda etc should not exist." and "Cosmologists believe that some unseen kind of matter - dark matter - surrounds and permeates Andromeda etc adding the necessary gravitational force to keep them spinning as observed". In the article they also speak about dark charge (one positive one negative), dark photons and dark electromagnetism. The problem is IMO there exists strictly speaking no visible matter. The only matter to explain galaxy rotating curves are its objects i.e. baryonic matter. Small baryonic objects are invisible. As such all earth sized objects are invisible. They only become visible when they grow in size, become hot both inside and outside and become visible like our sun, because now they emit photons we humans can observe. (which by itself is already amazing) At the same time they also should not grow to much in size because than they become invisible again (as black holes, which do not emit, photons which strictly speaking may not be correct) I'm aware that BH can be detected indirectly. My point is that in order to explain the rotation curves you should take care for all baryonic mass specific outside the observable disc. The issue is partly how much baryonic matter is there in the regions between stars. For our sun this region starts with the spherical Oort Cloud, but in real each star has an Oort Cloud. When this amount of matter is large it should be included in the calculations of a galaxy rotation disc. Anyway when our Galaxy contains lots of darkmatter why does our own solair system not contain anything. If it does it could explain the forward movement of the planet Mercury (which it should not?) Nicolaas Vroom http://users.pandora.be/nicvroom/ [[Mod. note -- 1. Earth-sized and even smaller baryonic objects may be detectable by microlensing. See, for example, arXiv:1001.3349. 2. When we use a measured galaxy rotation curve to estimate (model) the mass distribution, we're implicitly including ALL mass that gravitates, including the Oort clouds of all the stars. 3. When we say our galaxy contains "lots" of dark matter, that means "enough to be dynamically significant on the scale of the galaxy". If you do the numbers, you'll see that a dark-matter density can be big enough to be dynamically significant on the scale of the galaxy (i.e., significantly affect the galactic rotation curve), yet the amount of dark matter within our solar system is still far too tiny to be detected in planetary motions. The key point is that the galaxy is HUGE relative to our solar system, so even a tiny density (too small to be important within our solar system) can add up to a significant amount of matter on a galactic scale. -- jt]] |
#2
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Mystery of the hidden cosmos.
Op zaterdag 11 juli 2015 20:54:24 UTC+2 schreef Nicolaas Vroom:
[[Mod. note -- 1. Earth-sized and even smaller baryonic objects may be detectable by microlensing. See, for example, arXiv:1001.3349. I agree. The question is what is the total mass of the objects in our Galaxy related to size. See the article "The Grand Illusion" in Astronomy of November 1992 by Ken Croswell. What the article implies is that the majority of stars in Our Galaxy are Red and White dwarfs. That means a lot of mass comes from red stars. My interpretation is 50%. K dwarfs 25% and all others 25%. And that inturn means IMO that the amount of matter from even smaller objects can be huge (which is all baryonic) 2. When we use a measured galaxy rotation curve to estimate (model) the mass distribution, we're implicitly including ALL mass that gravitates, including the Oort clouds of all the stars. There are always three questions: 1. How much matter do we need to simulate a galaxy rotation curve. 2. How much baryonic matter can we observe including blackholes. 3. How much matter is missing. 4. What is the density (distribution) of this matter. 5. Could all this missing matter be baryonic ? 3. When we say our galaxy contains "lots" of dark matter, that means "enough to be dynamically significant on the scale of the galaxy". At the same time this is also true for baryonic matter. I have also done some simulations. For some information go he http://users.telenet.be/nicvroom/dark_mat.htm If you do the numbers, you'll see that a dark-matter density can be big enough to be dynamically significant on the scale of the galaxy (i.e., significantly affect the galactic rotation curve), yet the amount of dark matter within our solar system is still far too tiny to be detected in planetary motions. I fully agree with you that a certain amount of matter is missing dynamically significant etc. The issue is that we must be sure that it is not baryonic before we can start to investigate something else. The key point is that the galaxy is HUGE relative to our solar system, so even a tiny density (too small to be important within our solar system) can add up to a significant amount of matter on a galactic scale. The question is what is this missing (dark) matter density compared to the Oort Cloud density. The fact that there is (almost) no dark matter in our solar system implies me to postulate that there is no dark matter around the direct neighbourhood of any star (planetary system) -- jt]] Nicolaas Vroom. |
#3
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Mystery of the hidden cosmos.
In article ,
Nicolaas Vroom writes: [[Mod. note -- 1. Earth-sized and even smaller baryonic objects may be detectable by microlensing. See, for example, arXiv:1001.3349. I agree. The question is what is the total mass of the objects in our Galaxy related to size. See the article "The Grand Illusion" in Astronomy of November 1992 by Ken Croswell. That is 23 years old! That is a LONG TIME in modern astronomy. What the article implies is that the majority of stars in Our Galaxy are Red and White dwarfs. Yes. That means a lot of mass comes from red stars. Yes. My interpretation is 50%. I'm sure that there are better estimates. K dwarfs 25% and all others 25%. And that inturn means IMO that the amount of matter from even smaller objects can be huge (which is all baryonic) Both red and white dwarfs shine. We have an idea how many there are. They are not unaccounted for. 2. When we use a measured galaxy rotation curve to estimate (model) the mass distribution, we're implicitly including ALL mass that gravitates, including the Oort clouds of all the stars. Right. And since the resulting mass is always larger than everything we know about, we invoke dark matter. Or MOND. There are always three questions: 1. How much matter do we need to simulate a galaxy rotation curve. 2. How much baryonic matter can we observe including blackholes. 3. How much matter is missing. 4. What is the density (distribution) of this matter. 5. Could all this missing matter be baryonic ? Any review of dark matter can answer these questions. Maybe one could just about manage to have all missing matter in spiral galaxies be baryonic, pushing the limits, but there is evidence for more dark matter, which makes it more probable that it exists in spiral galaxies as well. |
#4
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Mystery of the hidden cosmos.
On Tuesday, July 14, 2015 at 2:40:47 AM UTC-6, Phillip Helbig (undress to reply) wrote:
In article , Nicolaas Vroom writes: [[Mod. note -- 1. Earth-sized and even smaller baryonic objects may be detectable by microlensing. See, for example, arXiv:1001.3349. I agree. The question is what is the total mass of the objects in our Galaxy related to size. See the article "The Grand Illusion" in Astronomy of November 1992 by Ken Croswell. That is 23 years old! That is a LONG TIME in modern astronomy. What the article implies is that the majority of stars in Our Galaxy are Red and White dwarfs. Yes. That means a lot of mass comes from red stars. Yes. My interpretation is 50%. I'm sure that there are better estimates. I did a semi-quantitative estimate from the number of type O through type M with their mass ranges and came up with about 41% of the total O through M mass. K dwarfs 25% I'm close at 24%, so I agree. and all others 25%. I'm talking about percentages of SHINING stars, so I get 35% for all others, making a total of 100%. And that inturn means IMO that the amount of matter from even smaller objects can be huge (which is all baryonic) Well, by extrapolating frequency and masses below type M stars, I get about another 45% for brown dwarves and maybe another 10% for smaller objects. The masses of even smaller objects drops to insignificance (even though the extrapolation says they are much, much more numerous than stars and brown dwarves. If this extrapolation has any validity, it means that "agglomerated" baryonic matter is far short of being able to explain the dark matter problem. Additional gas has been detected in galactic haloes and has been identified as supernova ejections. One would expect that ejection should be symmetric so much of it was ejected into the galactic disk, but this can only amount to a few percent. Both red and white dwarfs shine. We have an idea how many there are. They are not unaccounted for. 2. When we use a measured galaxy rotation curve to estimate (model) the mass distribution, we're implicitly including ALL mass that gravitates, including the Oort clouds of all the stars. Right. And since the resulting mass is always larger than everything we know about, we invoke dark matter. Or MOND. There are always three questions: 1. How much matter do we need to simulate a galaxy rotation curve. 2. How much baryonic matter can we observe including blackholes. 3. How much matter is missing. 4. What is the density (distribution) of this matter. 5. Could all this missing matter be baryonic ? Any review of dark matter can answer these questions. Maybe one could just about manage to have all missing matter in spiral galaxies be baryonic, pushing the limits, but there is evidence for more dark matter, which makes it more probable that it exists in spiral galaxies as well. Yes, there is a real deficit problem unless the microlensing technique can demonstrate that planet-sized objects are thicker than fleas on a dog (i.e., my extrapolation wildly underestimates the number of these bodies by several orders of magnitude). Gary |
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Mystery of the hidden cosmos.
Op dinsdag 14 juli 2015 10:40:47 UTC+2 schreef Phillip Helbig:
That is 23 years old! That is a LONG TIME in modern astronomy. I have no more recent information I'm sure that there are better estimates. You can also also claim that there are 60% Red and white dwarfs, 20% K dwarfs all others 20% (equally divided in G stars, A+F stars and larger stars). K dwarfs 25% and all others 25%. And that inturn means IMO that the amount of matter from even smaller objects can be huge (which is all baryonic) Both red and white dwarfs shine. We have an idea how many there are. They are not unaccounted for. Correct. This defines "all" visible baryonic matter That means, as a matter of argument, that there could exist almost the same amount of brown stars, planet sized stars and dust (all "invisible" baryonic matter). 2. When we use a measured galaxy rotation curve to estimate (model) the mass distribution, we're implicitly including ALL mass that gravitates, including the Oort clouds of all the stars. Right. And since the resulting mass is always larger than everything we know about, we invoke dark matter. Or MOND. IMO when the calculated theoretical mass is more than the observed baryonic mass the first candidate to invoke is baryonic grain sized mass. To modify from Newtonic mechanics to MOND is IMO not necessary. There are always three questions: 1. How much matter do we need to simulate a galaxy rotation curve. 2. How much baryonic matter can we observe including blackholes. 3. How much matter is missing. 4. What is the density (distribution) of this matter. 5. Could all this missing matter be baryonic ? Any review of dark matter can answer these questions. Maybe one could just about manage to have all missing matter in spiral galaxies be baryonic, pushing the limits, but there is evidence for more dark matter, which makes it more probable that it exists in spiral galaxies as well. In our solor system there is "no" dark matter. The line of evidence is linked to the trajectories of known planets at each epoch. These trajectories could not be explained by the existance of the known planets. The missing matter was explained by the observations of a new baryonic planet, not by invoking darkmatter which in essence is a new kind of physics. See: https://en.wikipedia.org/wiki/Discovery_of_Neptune. Only in the case of Mercury a new kind of physics was required. Nicolaas Vroom |
#6
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Mystery of the hidden cosmos.
On 7/16/2015 3:38 AM, Gary Harnagel wrote:
On Tuesday, July 14, 2015 at 2:40:47 AM UTC-6, Phillip Helbig (undress to reply) wrote: ... Any review of dark matter can answer these questions. Maybe one could just about manage to have all missing matter in spiral galaxies be baryonic, pushing the limits, but there is evidence for more dark matter, which makes it more probable that it exists in spiral galaxies as well. Yes, there is a real deficit problem unless the microlensing technique can demonstrate that planet-sized objects are thicker than fleas on a dog (i.e., my extrapolation wildly underestimates the number of these bodies by several orders of magnitude). Do we actually have strong limits on the total mass of our own Oort cloud? (Of course it should be in the order of one solar mass if together with similar clouds around stars it were to influence the rotation curve. So how unlikely is that?) -- Jos |
#7
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Mystery of the hidden cosmos.
Le 16/07/2015 22:24, Jos Bergervoet a écrit :
Do we actually have strong limits on the total mass of our own Oort cloud? That is the problem. We know very little actually. A new star was discovered not long ago, I reported that in this newsgroup. quote Images from the space telescopes also pinpointed the object's distance to 7.2 light-years away, earning it the title for fourth closest system to our sun. The closest system, a trio of stars, is Alpha Centauri, at about 4 light-years away. end quote from http://www.nasa.gov/jpl/wise/spitzer...dwarf-20140425 That is a huge object just SEVEN LIGHT YEARS AWAY! It is frozen cold, an old brown dwarf that has cooled to -48 Centigrade. We detected it because even at that temperature, it shines in the infrared and Spitzer saw it. It is one of the CLOSEST stars to the sun, right after alpha centauri system. And how do we detect those that are further away and cooled to maybe -150 centigrade? Really dark matter at those temperatures in the middle of integalactic space... We know nothing about deep space actually. The number of those objects could be big. And the comets? As Mr Bergervoet said: Do we actually have strong limits on the total mass of our own Oort cloud? New Horizons is going there now, having passed Pluto. Would the mass of the cloud interfere with the flight path of the spacecraft? Can the mass and speed of the spacecraft (that we can know very well) allow us to detect hidden masses that change the path? Or all those influences get destroyed by spacecraft movements to point the antenna or whatever? After transmitting the data, the spacecraft will go into hibernation, and subtle influences of gravitational forces could be (maybe) measured by determining the speed vector changes before/after hibernation with high precision. Or am I completely wrong? [[Mod. note -- I think New Horizons is planning a flyby of one Kuiper-belt object, and that flyby will probably give us a mass measurement for that object. Apart from that, it's very unlikely that New Horizons will come close enough to any other Kuiper-belt objects (they're *very* far apart!) for them to have a detectable influence on NH's trajectory. NH won't reach the Oort cloud in any of our lifetimes. -- jt]] |
#8
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Mystery of the hidden cosmos.
Op donderdag 16 juli 2015 22:24:07 UTC+2 schreef Jos Bergervoet:
On 7/16/2015 3:38 AM, Gary Harnagel wrote: Yes, there is a real deficit problem unless the microlensing technique can demonstrate that planet-sized objects are thicker than fleas on a dog (i.e., my extrapolation wildly underestimates the number of these bodies by several orders of magnitude). Do we actually have strong limits on the total mass of our own Oort cloud? Maybe there are more questions. The first question is slightly different: What is the shape of the Oort Cloud ? When you study the shape and size of Oort cloud in: https://en.wikipedia.org/wiki/Oort_cloud than you can see that its inner radius is small compared to its outer radius which is 10 times as large. The next question to answer is what is the mass of three times the inner radius multiplied by the average density of the Oort Cloud When this number is more or less the same you get an impression of how much baryonic matter there is in the Oort Cloud. The third question is: Is there really an Oort Cloud around each star with empty space between the Oort Cloud of each star. It is easy possible that this huge region is not empty which can inhabitate a lot of mass. (Of course it should be in the order of one solar mass if together with similar clouds around stars it were to influence the rotation curve. So how unlikely is that?) -- Jos The numbers should demonstrate the verdict. Nicolaas Vroom |
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Mystery of the hidden cosmos.
Op vrijdag 17 juli 2015 10:00:41 UTC+2 schreef jacobnavia:
We know nothing about deep space actually. The number of those objects could be big. And what about smaller objects? The question of course is should we not first study and solve (which means ?) this issue before we start introducing a new kind of matter called darkmatter which include dark forces (pos and neg), dark photons, dark electromagnetism, and all types of dark particles (light and heavy) This whole concept of dark photons is the more strange because the major difference is that we humans can only detect type 1 but not type 2 (dark). while in principle it is a physical issue. In fact the whole space surrounding me is filled with photons type 1. What happens when a type 2 photon enters in my room is a mystery. Accordingly to the SAm article there is a clear difference between type 1 matter and type 2 matter in the disc (proposal). That means type 1 is in the spiral arms and type 2 (dark) outside the spiral arms (which make the galaxy elliptical). How this clear distinction is reached or obtained (specific after a galaxy merge or collision) is also a mystery. A universe consisting of almost only baryonic matter is much simpler. (that leaves the door open of a universe consisting of only dark matter) Nicolaas Vroom |
#10
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Mystery of the hidden cosmos.
On Saturday, July 18, 2015 at 11:37:18 PM UTC-6, Nicolaas Vroom wrote:
Op donderdag 16 juli 2015 22:24:07 UTC+2 schreef Jos Bergervoet: On 7/16/2015 3:38 AM, Gary Harnagel wrote: Yes, there is a real deficit problem unless the microlensing technique can demonstrate that planet-sized objects are thicker than fleas on a dog (i.e., my extrapolation wildly underestimates the number of these bodies by several orders of magnitude). Do we actually have strong limits on the total mass of our own Oort cloud? Maybe there are more questions. The first question is slightly different: What is the shape of the Oort Cloud ? When you study the shape and size of Oort cloud in: https://en.wikipedia.org/wiki/Oort_cloud than you can see that its inner radius is small compared to its outer radius which is 10 times as large. The next question to answer is what is the mass of three times the inner radius multiplied by the average density of the Oort Cloud When this number is more or less the same you get an impression of how much baryonic matter there is in the Oort Cloud. Your link says the outer (spherical) Oort cloud has an estimated mass of about five earths. The inner (donut shaped) cloud "should have tens or hundreds of times as many cometary nuclei as the outer halo" So maybe a few Jupiters in terms of mass? That still less than one per cent of the solar mass. The third question is: Is there really an Oort Cloud around each star with empty space between the Oort Cloud of each star. It is easy possible that this huge region is not empty which can inhabitate a lot of mass. Your wiki link says the Oort cloud goes out two light years, which means that huge region is not empty, but it has been accounted for (apparently) in the five earth masses. (Of course it should be in the order of one solar mass if together with similar clouds around stars it were to influence the rotation curve. So how unlikely is that?) -- Jos The numbers should demonstrate the verdict. Nicolaas Vroom It appears to me that even with there being more and more stuff at smaller and smaller diameters throughout interstellar space, their volumes (and therefore their masses) goes as 1/r^3, so the maximum mass fraction occurs at the red dwarf/brown dwarf level. Not nearly enough to account for dark matter. Gary |
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