Purchase: http://hilaroad.com/video/ This video demonstrates how to find the Andromeda Galaxy (M31). This galaxy is 2.5 million light years from earth but with some basic knowledge of the night sky and a pair of binoculars it is actually possible to see it! The video is designed for anyone interested in astronomy and it also provides support for the astronomy component of any science curriculum.
Duration : 0:6:1
What is the adverage time for this to happen?
I read an article that said that the normal time is less than 10billion for the galaxies to start forming together, but what is the typical time for this to happen?
Thankyou(:
About a billion years, give or take. 10 billion is almost the whole age of the Universe.
Calculation:
Typical distances involved: 300 kpc
Typical velocities: 300 km/s = 300 kpc/Gyr
Typical time = 300 kpc/ 300kpc/Gyr = 1 Gyr
1 Two elliptical galaxies merge together.
2 An elliptical galaxy and a spiral galaxy merge together.
3 Two spiral galaxies merge together.
Let’s assume all of these combinations involve simalrly sized galaxies.
1. One more massive giant elliptical.
Since both galaxies are starved of gas and dust. The gravitational dance will be the same but a lot "colder" since there is no gas and dust to be ionized. Not so bright and dusty either. The SMBH’s will have little growth until they themselves collide. There will be less stellar streams since ellipticals are more compact and can hold onto their stars a lot better.
2. One more massive giant elliptical.
The spiral will suffer a lot in the gravitational dance since its gas and dust will be exhausted until there is nothing left to starburst activity and feeding SMBH. The merging process will be dusty and bright in IR (hence star formation and feeding SMBH’s). Stellar streams will be common as the arms trail behind the gravitational dance.
3. One more massive giant elliptical.
Same as two of course except that the scenario involves a lot more starburst activities and disruption.
Example: NGC6240, future Milkomeda, Antenna Galaxies
Clear skies!
If there were a Big Bang and we came from a single point then why do galaxies move in different directions and not at an outward expansion that points to that single reference point? Some galaxies move side ways like throwing a frisbee face on and some galaxies move like a frisbee but all are moving in a random direction and not from a single point.
For a few reasons.
1) Matter was not dispersed and expelled in perfectly parallel lines pointing outward from the central location of the big bang. Just like any other explosion you have seen on TV, the cloud it creates is not a perfect sphere of expanding material. Some material goes shooting out faster in one direction some slower in other directions. There also might have been numerous explosions that followed the big bang as the matter was still quite hot and unstable, creating further complexities.
2) As the matter from the big bang was not spread out uniformly, clumps of higher density came together to form galaxies and stars, etc. Just like our solar system has a motion around the center of our galaxy along one of the arms, galaxies are moving in their own groups (clusters), as well as super clusters that are gravitationally bound as well.
Since we are still moving away from the point where the big bang occurred, all galaxies are also moving away from us (and each other). Though, this does not give us a calculable center point of where the big bang occurred.
I see that the Galaxies are concentrated in two parts of the sky, why are they thicker at those spots and why dont they appear to be distributed evenly throughout the sky? TEN POINTS TO THE FIRST GOOD ANSWER!
Galaxies aren’t evenly distributed because of tiny density variations in the earliest moments of the big bang. These initially tiny variations are believed to have been caused by small quantum fluctuations. The tiny variations were expanded by many orders of magnitude during the era of inflation with the result that the universe after the big bang was inhomogeneous on a large scale. Gravity then caused the denser concentrations of matter (especially dark matter) to collapse. The first stars formed out of the collapsing clouds, and stars were drawn into galaxies. Now, matter is distributed in a netlike array with fine filaments forming the net and the filaments separated by enormous voids. The filaments are composed of galactic super-clusters which in turn are composed of galactic clusters which are composed of galaxies. Some super-clusters are arranged in what is called "attractors," enormous concentrations of galaxies. However, the universal network of matter is not concentrated in any one part of the sky from the earth’s point of view. One looks out upon a series of filaments, the network, and those filaments exist in every direction. There are, however, nearby (relatively) dust lanes that obscure parts of the network as seen from earth.
The argument that scientists have for there not being a center of the universe is that galaxies will reeceed away from you no matter where your located in the universe. How do they know that if they never been to another galaxy?
They don’t. However, they hold very dearly to the principle of relativity, that the laws of physics are the same in all inertial reference frames and have the same form in all reference frames in general. In brief, this means that there are no "special" places from which to view the Universe. It is difficult to know if this is really so, given the impossibility of going significantly "elsewhere". One can, however, make measurements such as the atomic or molecular spectroscopic features imprinted on light from distant stars that passes through intervening clouds of dust and gas or the features caused by trace elements in a distant star itself. These data can be explained by the same physics we see at work here on Earth.
What two physical effects, are required in order to understand how we measure the speed at which galaxies are moving away from us in the Universe?
Best guess what your teacher is looking for:
Speed of Light
Doppler shift of the wavelengths of light from the galaxy (Red Shift)
I could be wrong, but that is all I need.
I saw on the yahoo news where our galaxies are colliding what happens when they fully collide?
They generally merge into a single larger galaxy after jumbling around a bit. All large modern galaxies were formed from mergers of many protogalaxies. There is one observed case of a single spiral galaxy with two distinct populations of stars orbiting in opposite directions about the galatic center. It was presumably formed from the merger of two oppositely spinning galaxies.
Nebular theory: large cloud of gas and dust that collapses into a swirling disk, creates a massive star at the center and condensing planetesimals around it. Then, the planetesimals combine into planets.
As applied to galaxy: super-massive cloud of gas and dust collapses into a swirling disk with a massive object (black hole) at its center. Then, regions of gas and dust collect into countless smaller objects, which are still massive enough to form stars.
Seems to work, but my astronomy class didn’t/hasn’t really gone extensively over the formation of galaxies. What is current theory?
Thanks for your help!
You’re basically right.
But galaxy formation differs somewhat from star formation, in that the galaxy is mostly dark matter, and the dynamics of the dark matter dominate. The baryonic matter just "comes along for the ride" until it compresses and shocks.
There are two different scenarios for different masses of dark matter halos: adiabatic and isothermal. In smaller galaxies, the infalling gas tends to be isothermal, that is, it cools through radiation as it collapses. In bigger galaxies, the infalling gas heats adiabatically, which mitigates the collapse.
The black hole probably forms after the initial formation of the galaxy, and energy from the black hole likely feeds back and modifies the galaxy formation process.
I have heard that dark matter could possibly be the gravitational link between between distant galaxies. Could this possibly lead to the big crunch? Thanks
dark matter is believed existing whereever ammounts of matter are.
The relation between dark matter and galaxies is, that only the existance of dark matter would explain the odd rotation of those galaxies. Newtons law has predicted that the outer parts of galaxies would rotate much slower than it it is observed.
about dark matter and the universe itself…well… obviously most galaxies move away from each other even with dark matter in place. Reason: dark energy is believed to make the universe expand, or better the space between galaxies.
scientists think there is 73% dark energy, 23% dark matter and just 4% normal matter, these numbers may show why dark matter will not lead to a gravitational collapse.