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When Galaxies Collide
A new article in the July issue of Sky and Telescope mentions that about several billion years in the future, the Andromeda Galaxy will collide with the Milky Way. When that happens it seems feasible that both galaxies may merge to form a large elliptical galaxy, with the merged galaxy potentially forming an active galactic nucleus. An active galactic nucleus could potentially be a quasar, or at least some other very bright object producing large amounts of radiation from the infall of gas and dust, into the merged black hole, originating from both galaxies. Large elliptical galaxies are generally noted for very little gas and dust within them, producing virtually no new star formation. It has been conjectured that this is because very active galactic nuclei deriving from the infall of gas and dust into the supermassive black holes in the past produced radiation pressure from the central infall region, blowing all of the gas and dust out of the galaxy, perhaps in a slightly similar way to the ignition of a star also, sometimes blowing off the infalling gas and dust that may initially be forming it in a nebula. Many galaxies also have central regions with no star formation, also speculated to be caused by active galactic nuclei very early in their formation, blowing gas and dust away from the central regions. If the active galactic nuclei are less violent or negligable, there might be areas of gas and dust outward from the central bulge that then forms stars later, like the spiral arms of the Milky Way, with some if its later generation, metal rich stars. Two basic questions: 1. When the Andromeda and Milky Way collide several billion years in the future, how severe will be the radiation source from an active galactic nucleus that could potentially form from the merger? Would all of the gas and dust from both galaxies be blown off into intergalactic space, totally ending star formation in both galaxies, or would there still be a few areas at the far periphery that could still form stars? Could a collision of Andromeda with the Triangulum Galaxy potentially have any effects on the Milky Way, and when will that happen, if it happens? If there were life bearing plants in the merging galaxies at that later period in time, would it be enough to snuff out any potential life on such worlds? If a planet nearly identical to Earth with Earth-like life were situated 10,000, 30,000, 50,000, or 100,000 light years from the merged cores of both galaxies, would it produce virtually no changes to any life or civilizations on any of those worlds, or would it be enough to totally destroy life on a wide number of them? and 2. (mainly for alt.history.future) If by that time, both the Milky Way and the Andromeda galaxies had trans-galactic civilizations in both of them, would it be possible, useing known physics, to prevent the formation of an active galactic nucleus, from the merger, if for no other reason to preserve the existance of star forming regions in both of them? What sort of engineering feats would be required to prevent the infall of gas and dust into two merging supermassive black holes? Would this be an engineering feat physically impossible, even to two-trans galactic civilizations potentially spanning, millions or even billions of stars, several billion years in our future? |
#2
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When Galaxies Collide
Orbitan wrote:
A new article in the July issue of Sky and Telescope mentions that about several billion years in the future, the Andromeda Galaxy will collide with the Milky Way. When that happens it seems feasible that both galaxies may merge to form a large elliptical galaxy, with the merged galaxy potentially forming an active galactic nucleus. An active galactic nucleus could potentially be a quasar, or at least some other very bright object producing large amounts of radiation from the infall of gas and dust, into the merged black hole, originating from both galaxies. Large elliptical galaxies are generally noted for very little gas and dust within them, producing virtually no new star formation. It has been conjectured that this is because very active galactic nuclei deriving from the infall of gas and dust into the supermassive black holes in the past produced radiation pressure from the central infall region, blowing all of the gas and dust out of the galaxy, perhaps in a slightly similar way to the ignition of a star also, sometimes blowing off the infalling gas and dust that may initially be forming it in a nebula. Many galaxies also have central regions with no star formation, also speculated to be caused by active galactic nuclei very early in their formation, blowing gas and dust away from the central regions. If the active galactic nuclei are less violent or negligable, there might be areas of gas and dust outward from the central bulge that then forms stars later, like the spiral arms of the Milky Way, with some if its later generation, metal rich stars. Two basic questions: 1. When the Andromeda and Milky Way collide several billion years in the future, how severe will be the radiation source from an active galactic nucleus that could potentially form from the merger? Would all of the gas and dust from both galaxies be blown off into intergalactic space, totally ending star formation in both galaxies, or would there still be a few areas at the far periphery that could still form stars? Could a collision of Andromeda with the Triangulum Galaxy potentially have any effects on the Milky Way, and when will that happen, if it happens? If there were life bearing plants in the merging galaxies at that later period in time, would it be enough to snuff out any potential life on such worlds? If a planet nearly identical to Earth with Earth-like life were situated 10,000, 30,000, 50,000, or 100,000 light years from the merged cores of both galaxies, would it produce virtually no changes to any life or civilizations on any of those worlds, or would it be enough to totally destroy life on a wide number of them? and 2. (mainly for alt.history.future) If by that time, both the Milky Way and the Andromeda galaxies had trans-galactic civilizations in both of them, would it be possible, useing known physics, to prevent the formation of an active galactic nucleus, from the merger, if for no other reason to preserve the existance of star forming regions in both of them? What sort of engineering feats would be required to prevent the infall of gas and dust into two merging supermassive black holes? Would this be an engineering feat physically impossible, even to two-trans galactic civilizations potentially spanning, millions or even billions of stars, several billion years in our future? I would think that just the extreme stellar-level gravitational chaos of a galactic collision would send stars and their planets out of their orbits and off in all sorts of diections, quickly killing whatever life they may harbor. -- ___________________________________________ ____ _______________ Regards, | |\ ____ | | | | |\ Michael G. Koerner May they | | | | | | rise again! Appleton, Wisconsin USA | | | | | | ___________________________________________ | | | | | | _______________ |
#3
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When Galaxies Collide
Orbital wrote:
A new article in the July issue of Sky and Telescope mentions that about several billion years in the future, the Andromeda Galaxy will collide with the Milky Way. Actually, any such article is almost certainly wrong. Although we might measure the line of sight velocity of the Andromeda galaxy (and even the interpretation of that is subject to dispute by Arp and others), we cannot measure the radial motion accurately. This means that even if they are moving towards each other they will highly likely miss. In so doing they would orbit endlessly and not hit. -- Ray Tomes http://ray.tomes.biz/ http://www.cyclesresearchinstitute.org/ |
#4
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When Galaxies Collide
In article , Ray Tomes
wrote: Orbital wrote: A new article in the July issue of Sky and Telescope mentions that about several billion years in the future, the Andromeda Galaxy will collide with the Milky Way. Actually, any such article is almost certainly wrong. Although we might measure the line of sight velocity of the Andromeda galaxy (and even the interpretation of that is subject to dispute by Arp and others), we cannot measure the radial motion accurately. This means that even if they are moving towards each other they will highly likely miss. In so doing they would orbit endlessly and not hit. Um isn't the Radial velocity the line of sight one. The proper, tangential motion is the one we cannot measure properly. Redshift can be measured quite well, and that gives us a measure of the radial velocity via Hubble. -- The true enemy of science is psuedoscience... |
#5
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When Galaxies Collide
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several billion years in the future, the Andromeda Galaxy will collide with the Milky Way. Actually, any such article is almost certainly wrong. Actually, the people who work in this field are quite competent. They look at detailed radio maps of the streamers of gas around galaxies in detail and so on; they examine a good deal of evidence beyond simple redshift. This is not my particular field but I've had a course in galactic dynamics and it is not full of simple-minded people - if the experts in the field did predict a collision and/or merger - and I know they were talking about this ten years ago - then they are very likely right, within whatever error bars they give. Although we might measure the line of sight velocity of the Andromeda galaxy (and even the interpretation of that is subject to dispute by Arp and others), we cannot measure the radial motion accurately. Um isn't the Radial velocity the line of sight one. The proper, tangential motion is the one we cannot measure properly. Second poster is correct, I assume the first poster just made a typo. The first poster has a good point that redshift alone is insufficient to predict a collision; my point is that the people who work in galactic dynamics examine many kinds of evidence before making predictions. Is there a what-if here? |
#6
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When Galaxies Collide
Orbitan wrote:
A new article in the July issue of Sky and Telescope mentions that about several billion years in the future, the Andromeda Galaxy will collide with the Milky Way. When that happens it seems feasible that both galaxies may merge to form a large elliptical galaxy, with the merged galaxy potentially forming an active galactic nucleus. An active galactic nucleus could potentially be a quasar, or at least some other very bright object producing large amounts of radiation from the infall of gas and dust, into the merged black hole, originating from both galaxies. Large elliptical galaxies are generally noted for very little gas and dust within them, producing virtually no new star formation. It has been conjectured that this is because very active galactic nuclei deriving from the infall of gas and dust into the supermassive black holes in the past produced radiation pressure from the central infall region, blowing all of the gas and dust out of the galaxy, perhaps in a slightly similar way to the ignition of a star also, sometimes blowing off the infalling gas and dust that may initially be forming it in a nebula. Many galaxies also have central regions with no star formation, also speculated to be caused by active galactic nuclei very early in their formation, blowing gas and dust away from the central regions. If the active galactic nuclei are less violent or negligable, there might be areas of gas and dust outward from the central bulge that then forms stars later, like the spiral arms of the Milky Way, with some if its later generation, metal rich stars. Two basic questions: 1. When the Andromeda and Milky Way collide several billion years in the future, how severe will be the radiation source from an active galactic nucleus that could potentially form from the merger? Would all of the gas and dust from both galaxies be blown off into intergalactic space, totally ending star formation in both galaxies, or would there still be a few areas at the far periphery that could still form stars? Could a collision of Andromeda with the Triangulum Galaxy potentially have any effects on the Milky Way, and when will that happen, if it happens? If there were life bearing plants in the merging galaxies at that later period in time, would it be enough to snuff out any potential life on such worlds? If a planet nearly identical to Earth with Earth-like life were situated 10,000, 30,000, 50,000, or 100,000 light years from the merged cores of both galaxies, would it produce virtually no changes to any life or civilizations on any of those worlds, or would it be enough to totally destroy life on a wide number of them? and 2. (mainly for alt.history.future) If by that time, both the Milky Way and the Andromeda galaxies had trans-galactic civilizations in both of them, would it be possible, useing known physics, to prevent the formation of an active galactic nucleus, from the merger, if for no other reason to preserve the existance of star forming regions in both of them? What sort of engineering feats would be required to prevent the infall of gas and dust into two merging supermassive black holes? Would this be an engineering feat physically impossible, even to two-trans galactic civilizations potentially spanning, millions or even billions of stars, several billion years in our future? http://www.public.iastate.edu/~astro...cts/curt2.html http://nedwww.ipac.caltech.edu/level...as/frames.html http://edu-observatory.org/eo/galaxies.html |
#7
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When Galaxies Collide
2006-06-02 .com,
paulaireilly wrote: Second poster is correct, I assume the first poster just made a typo. The first poster has a good point that redshift alone is insufficient to predict a collision; my point is that the people who work in galactic dynamics examine many kinds of evidence before making predictions. But galaxies aren't solid - I've read online about estimates on the number of star-star collisions that a galactic collision would entail. Some such estimates have been as high as a dozen. |
#8
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When Galaxies Collide
Jordan Abel wrote: 2006-06-02 .com, paulaireilly wrote: Second poster is correct, I assume the first poster just made a typo. The first poster has a good point that redshift alone is insufficient to predict a collision; my point is that the people who work in galactic dynamics examine many kinds of evidence before making predictions. But galaxies aren't solid - I've read online about estimates on the number of star-star collisions that a galactic collision would entail. Some such estimates have been as high as a dozen. Galaxies are very far from solid, but a galactic collision does several things. 1. Galaxies are typically far from virialized. The relaxation time for stellar orbits in a galaxy of even moderate size are orders of magnitude greater than the age of the Universe. I.e., there is a great deal of "structure" in galaxies, even elliptical galaxies. When two galaxies collide, these structures are changed. Typically a small number of stars are thrown out at high speed, and the remainder tend to collapse toward the new core. It is believed that the new structure tends to settle down toward 'elliptical' or giant elliptical. Giant ellipticals often have several dense areas in their cores - it is thought these may each be centered on large (millions+ of solar masses) black holes, which probably came from the cores of galaxies that merged to form the giant ellipticals. We cannot wait and see this process happening, but we can see many galaxies in various stages of this process of collision and merger, and do simulations that look a good deal like what we see around us. 2. Galaxies, especially spirals and irregulars, have a good deal of gas in them. Gas clouds DO collide, with shock waves, heating, star formation, and so on. Galactic collisions and mergers are not merely gravitational events; they are violent because these clouds hit at high speeds (hundreds of kilometers per second) and a great deal of energy is released. This is why galactic collisions can look spectacular. The colliding gas clouds are brilliant in certain regions of the spectrum, and trigger star formation, including giant young stars that are brilliant in visible light. Is there a what-if here? Why is this not in an astronomy group? I am not sure how to redirect followups. |
#9
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When Galaxies Collide
Ray Tomes wrote:
Actually, any such article is almost certainly wrong. Although we might measure the line of sight velocity of the Andromeda galaxy (and even the interpretation of that is subject to dispute by Arp and others), we cannot measure the radial motion accurately. This means that even if they are moving towards each other they will highly likely miss. In so doing they would orbit endlessly and not hit. Arp and others have been discredited for some time in such claims. And, more importantly, their claims are for objects such as quasars, not nearby galaxies such as the Andromeda galaxy. The distance to it has much smaller error bars based on multiple overlapping distance tests (distance determined by using Cepheid variables and other methods, not Hubble expansion). So, your reliance on anything they say to support your own claim is bogus. More to the point, radial velocity measurements provide line of sight measurements of motion. What you are likely attempting to talk about is tangential velocity, that is, motion across the line of sight. At this time, the Andromeda galaxy is far enough away from us that it shows no proper motion, which can be translated into tangential velocity knowing the distance to it. So, what you more properly should have said is that there is no knowledge of its total velocity (tangential and radial), so it could miss. As to orbiting endlessly, this is not likely as they are mutually pulling on each other and will eventually collide. Whether it will happen in about 3 billion years or not remains to be determined. Most simulations showing a direct impact show them passing through each other and merging at an even later date. Those passes may eventually strip much of the remaining gas from each or cause that gas to be compressed enough to create a burst of star formation, using it up. Also it is likely that such a pass will likely jettison stars from each into the space surrounding them. |
#10
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When Galaxies Collide
Orbitan wrote: A new article in the July issue of Sky and Telescope mentions that about several billion years in the future, the Andromeda Galaxy will collide with the Milky Way. When that happens it seems feasible that both galaxies may merge to form a large elliptical galaxy, with the merged galaxy potentially forming an active galactic nucleus. An active galactic nucleus could potentially be a quasar, or at least some other very bright object producing large amounts of radiation from the infall of gas and dust, into the merged black hole, originating from both galaxies. Large elliptical galaxies are generally noted for very little gas and dust within them, producing virtually no new star formation. It has been conjectured that this is because very active galactic nuclei deriving from the infall of gas and dust into the supermassive black holes in the past produced radiation pressure from the central infall region, blowing all of the gas and dust out of the galaxy, perhaps in a slightly similar way to the ignition of a star also, sometimes blowing off the infalling gas and dust that may initially be forming it in a nebula. Many galaxies also have central regions with no star formation, also speculated to be caused by active galactic nuclei very early in their formation, blowing gas and dust away from the central regions. If the active galactic nuclei are less violent or negligable, there might be areas of gas and dust outward from the central bulge that then forms stars later, like the spiral arms of the Milky Way, with some if its later generation, metal rich stars. Two basic questions: 1. When the Andromeda and Milky Way collide several billion years in the future, how severe will be the radiation source from an active galactic nucleus that could potentially form from the merger? Would all of the gas and dust from both galaxies be blown off into intergalactic space, totally ending star formation in both galaxies, or would there still be a few areas at the far periphery that could still form stars? Could a collision of Andromeda with the Triangulum Galaxy potentially have any effects on the Milky Way, and when will that happen, if it happens? If there were life bearing plants in the merging galaxies at that later period in time, would it be enough to snuff out any potential life on such worlds? If a planet nearly identical to Earth with Earth-like life were situated 10,000, 30,000, 50,000, or 100,000 light years from the merged cores of both galaxies, would it produce virtually no changes to any life or civilizations on any of those worlds, or would it be enough to totally destroy life on a wide number of them? The chances are that any life on a planet wouldn't even know the galaxies are colliding. and 2. (mainly for alt.history.future) If by that time, both the Milky Way and the Andromeda galaxies had trans-galactic civilizations in both of them, would it be possible, useing known physics, to prevent the formation of an active galactic nucleus, from the merger, if for no other reason to preserve the existance of star forming regions in both of them? No, since the "known" laws of physics of galaxies are actually unknown laws of dark matter. What sort of engineering feats would be required to prevent the infall of gas and dust into two merging supermassive black holes? Would this be an engineering feat physically impossible, even to two-trans galactic civilizations potentially spanning, millions or even billions of stars, several billion years in our future? |
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