This article carries this sentence. "Solid gold is mainly formed through geological processes in large veins underground."BMAONE23 wrote:Ah the Midas Bacterium...That golden touchBDanielMayfield wrote:The bacterium doesn’t make gold, it excretes gold that was suspended in water. Still, it could be a very useful discovery.
http://www.abc.net.au/science/articles/ ... 682812.htm
The question should be: Who is correct, the geologists or the microbiologists?Propsector wrote:This article carries this sentence. "Solid gold is mainly formed through geological processes in large veins underground."BMAONE23 wrote:Ah the Midas Bacterium...That golden touchBDanielMayfield wrote:
The bacterium doesn’t make gold, it excretes gold that was suspended in water. Still, it could be a very useful discovery.
http://www.abc.net.au/science/articles/ ... 682812.htm
Who is correct, the geologists or the astrophysicists?
The astronomers are looking at a mechanism that explains the delivery of atoms of gold to the surface and outer crust of the Earth. The geologists and biologists are looking at mechanisms that concentrate those atoms into veins. Different questions. They can all be correct.Propsector wrote:This article carries this sentence. "Solid gold is mainly formed through geological processes in large veins underground."
Who is correct, the geologists or the astrophysicists?
Universe is under 13.77B years old. Milky Ways is 13.2B years old. Solar System is 4.6 B years old expected to last another 4+B years more or 9-10B years before our Sun turns into a hot white dwarf.
P.S. It is now thought that something even more exotic could be required to build heavy elements like Au and Pu; a supernova caused by the collision of two neutron stars. This may sound like it might be an impossibly rare event but it does occur fairly regularly. This is because binary stars are very common and because the neutron star state is a common condition that massive stars can collapse into after going supernova. Two neutron stars in a tight orbit will be drawn toward each other until they collide. So, it could be that it may take a series of THREE supernova explosions to form Gold!
(See the news bystander has colected for us here : http://asterisk.apod.com/viewtopic.php?f=31&t=31783)
P.S.S. The explosion caused by the collision of two neutron stars is only 0.1 to 0.01 as powerfull as the average supernova, and 1,000 times as powerful as a typical nova, so they are calling these kilonovas. But they still rock. One kilonova is reported to be able to produce 10 of our Moon's worth of gold!
The 2 supernova are probably the consequence of a massive binary star system in which the core collapse of both stars end up producing neutron stars (not black holes). The neutron star binary then radiates of gravitational wave until they collide creating and ejecting elements heavier than iron/nickel while presumably leaving behind a single black hole.ErnieM wrote:
Universe is under 13.77B years old. Milky Ways is 13.2B years old. Solar System is 4.6 B years old expected to last another 4+B years more or 9-10B years before our Sun turns into a hot white dwarf.
This leaves 8-9B years for the series of THREE supernova, or a TWIN supernova THIRD supernova, or ONE kilonova plus (TWO supernova or nova or ONE of each) events to occur and give birth to GOLD on the Solar System. Do I have these numbers right?
Besides the Solar System, each of these events also would have created a black hole. Where are these THREE black holes now?
From this one could infer that extra-solar systems with rocky planet(s) are the product of this process. If the process also gave birth to a black hole, where are these black holes now? How far is the Solar system from its "mother" black hole? Is 13.2B years long enough for it to evaporate? Can the size of the black hole be calculated from the total mass of the Solar system?The 2 supernova are probably the consequence of a massive binary star system in which the core collapse of both stars end up producing neutron stars (not black holes). The neutron star binary then radiates of gravitational wave until they collide creating and ejecting elements heavier than iron/nickel while presumably leaving behind a single black hole.
Planetary systems usually form in dense nebulas, with a high stellar density including many massive stars. Nearby supernovas are probably common. If black holes result, they could be anywhere- except for the small percentage with accretion discs, they are generally not detectable.ErnieM wrote:From this one could infer that extra-solar systems with rocky planet(s) are the product of this process. If the process also gave birth to a black hole, where are these black holes now? How far is the Solar system from its "mother" black hole? Is 13.2B years long enough for it to evaporate? Can the size of the black hole be calculated from the total mass of the Solar system?
BDanielMayfield wrote:
The bacterium doesn’t make gold, it excretes gold that was suspended in water. http://www.abc.net.au/science/articles/ ... 682812.htm
http://en.wikipedia.org/wiki/Futurama wrote:
<<Nibbler is Leela's pet Nibblonian, whom she rescues from an imploding planet and adopted in the episode "Love's Labours Lost in Space". Lord Nibbler masquerades as an innocent, cute and unintelligent pet during most of the series. In reality, he is highly intelligent and capable of communication, but tries to avoid suspicion while he goes about his mission of protecting the Earth in general and Fry in particular from the evil Brainspawn. Nibbler's feces consist of dark matter (as the feces of all of those of his species do), which can be used as starship fuel. It is an extremely dense material, "each pound of which weighs over ten thousand pounds", according to Professor Farnsworth.>>
All matter in a dense nebulae including its black hole(s) and any amount of dark matter are bound by gravity. So are the stars and planetary systems that formed from the same nebulae. Together they orbit the galaxy as a local group in the same radial zone.Planetary systems usually form in dense nebulas, with a high stellar density including many massive stars. Nearby supernovas are probably common. If black holes result, they could be anywhere- except for the small percentage with accretion discs, they are generally not detectable.
Since the birth of the solar system, we have made many orbits around the galaxy. It's as if we were in a big blender. Stars that formed alongside ours could be dispersed throughout the galaxy (although I'd expect most to be in a similar radial zone). Probably, locating any components from our zone of formation, whether evolved stars or remnant neutron stars or black holes, is impossible.
Certainly, no stellar mass black hole has ever evaporated, as this requires a time much greater than the age of the Universe, by many, many orders of magnitude.
No, this is not the case. The material in a nebula is only very loosely bound gravitationally. Some of the nebular mass is concentrated into stars as they are formed, and some is lost as the stellar radiation pressure causes it to dissipate. Gravitational perturbations very early on eject stars (that is, they are tweaked into hyperbolic orbits with respect to the center of mass of the nebula contents, including other stars). So there is no reason at all to think our solar system is anywhere near other stars that formed in the same stellar nursery, and we don't have enough information about the precise location and dynamics of all the galactic material to integrate very far backwards to find where things actually were long ago. In fact, this is probably an inherently unsolvable problem.ErnieM wrote:All matter in a dense nebulae including its black hole(s) and any amount of dark matter are bound by gravity. So are the stars and planetary systems that formed from the same nebulae. Together they orbit the galaxy as a local group in the same radial zone.
There's little reason to think the nearest stars are siblings. Most differ significantly in age. Also, there is no reason to expect any original black holes to have remained local, nor to expect them to contribute significantly to any local center of gravity. Keep in mind these would simply be stellar mass black holes. Dynamically, they are no different from stars, but stars are far more abundant.The list of nearest stars (http://en.wikipedia.org/wiki/Nearest_star), could all be siblings of our Solar system. The black hole(s) formed in the original nebulae must also be in this locality and serving as the locality's center of gravity, the center where local members orbit around.
"Our" black hole, or any stellar mass black hole, cannot be distinguished gravitationally from any star. Gravity wave detectors cannot detect ordinary black holes. Detectable gravity waves are formed by the collision of black holes, or by processes around supermassive black holes. These are completely different things.Our black hole(s) will be detected and found by gravity wave detectors of the future? Only question is not IF but WHEN, before evaporation.
Viewed from Orion, I wonder about the shape of the "asterism or constellation" our Sun is a member of. Are the stars in constellations we see from Earth not bound by gravity? I imagine they are because the shapes they take are cyclical from our perspective. If so, how and when did this happen? Did they just randomly happen to catch each other as they travel in their respective hyperbolic orbits? Are the stars in the same constellation of same age and properties? Even if they are not, this does not mean they come from different nurseries.No, this is not the case. The material in a nebula is only very loosely bound gravitationally. Some of the nebular mass is concentrated into stars as they are formed, and some is lost as the stellar radiation pressure causes it to dissipate. Gravitational perturbations very early on eject stars (that is, they are tweaked into hyperbolic orbits with respect to the center of mass of the nebula contents, including other stars). So there is no reason at all to think our solar system is anywhere near other stars that formed in the same stellar nursery, and we don't have enough information about the precise location and dynamics of all the galactic material to integrate very far backwards to find where things actually were long ago. In fact, this is probably an inherently unsolvable problem.
By siblings, I don't mean twins. If the original black holes did not remain local, were they also kicked out and took the hyperbolic trajectory wandering alone in the galaxy? As these black holes are of stellar mass, any chance there could be black holes with solid rocky planets? They would be pretty hard to see. So we will never know.There's little reason to think the nearest stars are siblings. Most differ significantly in age. Also, there is no reason to expect any original black holes to have remained local, nor to expect them to contribute significantly to any local center of gravity. Keep in mind these would simply be stellar mass black holes. Dynamically, they are no different from stars, but stars are far more abundant.
What would determine the mass of the resulting black holes? From wikipedia : "A stellar black hole (or stellar mass black hole) is a black hole formed by the gravitational collapse of a massive star.[1] They have masses ranging from about 3 to several tens of solar masses.[2] The process is observed as a supernova explosion[citation needed] or as a gamma ray burst[citation needed]. These black holes are also referred to as collapsars."Why would you expect stars formed in a nebula to be orbiting a black hole formed by a supernova in that nebula? If they weren't orbiting the star that exploded (and generally, why would they be?) they won't be orbiting it after it becomes a black hole, and has even less mass than it started with.
Galileo;s telescope has evolved and gave us the Hubble. Whose is to judge what future gravity/black hole wave detectors can do. Since these stellar black holes are very long lived, there is time for new detectors to evolve. No need to rush."Our" black hole, or any stellar mass black hole, cannot be distinguished gravitationally from any star. Gravity wave detectors cannot detect ordinary black holes. Detectable gravity waves are formed by the collision of black holes, or by processes around supermassive black holes. These are completely different things.
Keep in mind that the shortest evaporation time for any type of black hole known to actually exist is something like 60 orders of magnitude longer than the age of the Universe. For all practical purposes, we can consider stellar mass black holes to last forever.
ErnieM wrote:
Viewed from Orion, I wonder about the shape of the "asterism or constellation" our Sun is a member of.
ErnieM wrote:
Are the stars in constellations we see from Earth not bound by gravity? I imagine they are because the shapes they take are cyclical from our perspective.
No, they are not.ErnieM wrote:Are the stars in constellations we see from Earth not bound by gravity?
They are typically of very different ages, which does mean they didn't originate together. Stellar nurseries are very short lived- a few million years at most. That's the longest possible age spread for stars born from the same nebula. A random collection of stars making up any constellation (and for the most part, they are random) typically range in age over several billion years.Are the stars in the same constellation of same age and properties? Even if they are not, this does not mean they come from different nurseries.
Sure, you'd expect any black hole or neutron star remnants to be ejected just like any star. Indeed, even a small lack of isotropy in the forces produced during the supernova could eject the remnant, with no need for additional gravitational perturbations. In terms of dynamics, there's no reason a black hole couldn't have planets around it. Whether they could survive a local supernova is questionable. Some kind of later captures might be more likely.By siblings, I don't mean twins. If the original black holes did not remain local, were they also kicked out and took the hyperbolic trajectory wandering alone in the galaxy? As these black holes are of stellar mass, any chance there could be black holes with solid rocky planets?
They will be the mass of the original star, less the mass-energy equivalence released in the supernova, less the mass of the ejected material. Typically a few solar masses for a massive star.What would determine the mass of the resulting black holes?
It doesn't matter how good they are. The point is, a black hole doesn't generate gravity waves, and in terms of gravity itself, is indistinguishable from a star.Galileo;s telescope has evolved and gave us the Hubble. Whose is to judge what future gravity/black hole wave detectors can do. Since these stellar black holes are very long lived, there is time for new detectors to evolve. No need to rush.
Stars in a hyperbolic orbits must be going at velocities high enough to escape the gravity of the nebula. At such a high velocity, the star's gravity would not be strong enough to hold on to it's the planetary matter. If our Sun went through this, where did it acquire the material that formed our solar system? Are the matter in our Solar system from the same nebula that gave birth to our Sun?No, this is not the case. The material in a nebula is only very loosely bound gravitationally. Some of the nebular mass is concentrated into stars as they are formed, and some is lost as the stellar radiation pressure causes it to dissipate. Gravitational perturbations very early on eject stars (that is, they are tweaked into hyperbolic orbits with respect to the center of mass of the nebula contents, including other stars). So there is no reason at all to think our solar system is anywhere near other stars that formed in the same stellar nursery, and we don't have enough information about the precise location and dynamics of all the galactic material to integrate very far backwards to find where things actually were long ago. In fact, this is probably an inherently unsolvable problem.
The velocities required are not large. That's what it means to be loosely bound. For example, material in our own Oort cloud is in orbit around the Sun, but only loosely bound gravitationally. It requires only a few meters per second velocity change to radically change their orbits, often into hyperbolic ones. We observe that in the occasional long period comets on their way around the Sun and forever out of the Solar System.ErnieM wrote:Stars in a hyperbolic orbits must be going at velocities high enough to escape the gravity of the nebula. At such a high velocity, how a given star hold on to its planets or planetary matter?
Stars form their planetary systems (or at least, their protoplanetary discs) while still within their parent nebula. It is that nebula that supplies both the material making up the star, as well as the material making up its planetary system.If our Sun went to this, where did it acquire the material that formed our solar system?
I don't know anybody who thinks this is likely at all. The evidence is rather overwhelming that it was formed along with the other planets- its composition is as expected, and its circular, ecliptical orbit would be unlikely for a capture.THX1138 wrote:I’ve read someplace that there is some whom believe Uranus might very well be a planet that formed someplace else and was later captured by our sun.
It is estimated that a significant number of protoplanets get ejected from their parent system. This happens because orbiting systems of more than two bodies are inherently unstable. With time, bodies settle into semi-stable orbits (as in our own system), but while they are doing that all sorts of resonances develop with transfer angular momentum between them and can easily result in new, hyperbolic orbits and the ejection of planets.In any event what would be the possible mechanism by which the planet didn’t follow it’s parent star / how could it of gotten kicked out to of ended up orbiting our star, if that is indeed the case???
A very humbling picture.ErnieM wrote:
Viewed from Orion, I wonder about the shape of the "asterism or constellation" our Sun is a member of.
Whatever the shape our Sun wouldn't be a pare of it since it would only about a 12th magnitude star.
Sure it would. Magnitude 12 is pretty bright, so our system would be easily studied. We identify all sorts of candidates for systems similar to our own that have apparent magnitudes much dimmer. When looking for systems harboring life, apparent magnitude isn't a factor at all.ErnieM wrote:Imagine if there was an advanced civilization on the Orion system searching for other civilization, our Sun won't even make the list of possible candidate.
