Galaxies Definition and 425 Threads

As far as I understand, time dilation corresponding to redshift has been confirmed for distant supernova. However, galaxies are being detected only 480 million years after the bigbang at redshifts of around 10 or more. Does this mean they took less than 45 million years to form in real time?

why most of the galaxies are having two spiral arms only?

As I understand it, it isn't just the sapce between galaxies is stretching but new space is being created between galaxies, is that correct? If so are there any models that attemtp to explain what is generating the new space ? wheres does it come from?

I understand that spacetime is expanding between galaxies, as seen with the cosmological redshift. But, is it also expanding inside galaxies, such as the Milky Way? I'm not sure if the galaxy is gravitationally bound enough to where spacetime might actually be contracting within the galaxy...

How modern astronomy/cosmology rules out the possibility that some of observable galaxies are made of antimatter? Or within the same galaxy some stars/solar systems to be made of matter while others from antimatter? Isnt light emitted by antimatter exactly the same as that from matter?

I am wondering about the speed of the outer bands of galaxies and if they are moving at or faster than the speed of light? And then the thought of the speed of space expansion and and the body of the galaxy moving and the rotation of planets around the stars(solar system) and the spin of the...

Homework Statement my book states that approx 75% of galaxies in the universe are spirals, but then it says that out of a sample of 14 from the core of a large cluster of galaxies only 3 were found to be spiral. it was suggested we could use binomial distribution to look at the prob of...

I realize BBC science news is not a totally reliable source, but I'm wondering if any of the knowledgeable folks here have any comment on this: http://www.bbc.co.uk/news/science-environment-14948730 I tried to find if there had already been a thread on it, but I may have not looked hard...

I have understand that the Parallax method can be used to measure the distance to stars, but what happens when the parallax angle gets to small to be measures accurate? What kind of methods are used to measure distance to star that are like 5000 light years away, or to Superclusters that are...

First a true-false question. Are the furthest visible galaxies presently incapable of any connection with us. That is, the light coming from them 'now', is incapable of reaching us, ever, and vice versa. If this is true, and I assume it is then has there ever been an estimate of where the...

Homework Statement An object gives out a spectral line of 919nm compared to that of 589nm in a laboratory. It has a brigtness of 1.2 x 10-11 W m-2. The objective is to find out the brightness of the object if it were at 700 Mpc. Homework Equations 1. Z (redshift)= change in wavelength...

Hi, I'm working on a project on dwarf spheroidal galaxies. Is there a way to get a mass-to-light ratio knowing the distance to the galaxy, its size, and maybe some other parameters like the absolute magnitude or velocity dispersion? In the end, I'm trying to figure out their masses using...

So I was watching this: which talks about the winding paradox of spiral galaxies, e.g. the stars all move at the same relative speed however that shape is maintained. However, we still have those shapes. The video talks about density waves of some sort. I don't really understand. This...

Longo, "Detection of a Dipole in the Handedness of Spiral Galaxies with Redshifts z ~ 0.04," 2011, http://arxiv.org/abs/1104.2815 If this is right, then I guess it would be the first possible hint of a nonzero rate of rotation for the universe. He doesn't attempt to state his results in terms...

I don't know how to put my question into words so I'll give a brief example of what I want to say. The andromeda galaxy is a spiral galaxy 2.5 million lightyears from earth. When we observe it, we see it nearly on its plane. Light travels at a finite speed, so we see the andromeda galaxy as...

Hello all, My first post here. I do CG animations, and am working on a project where two galaxies collide. It is important to note up front that my simulation will NOT be physically accurate - I don't have the tools, knowledge, or processing power for that, but I AM interested in getting...

http://www.sciencedaily.com/releases/2005/01/050111115201.htm Please see this article. I've been trying to find the thread with 41 questions posted aces days ago. One of the questions was relating to high redshift objects like quasars appearing in near by galaxies. Someonevwanted a reference...

As an assignment I am trying to calculate the Hubble redshift by looking at spectra of galaxies... Obviously the very first thing I want to do is find a suitable emission line...i am trying to find the halpha line in all the spectra I am analysing. First off, there is a very large spike in the...

Moons revolve around planets. Planets revolve around stars. The entire solar system moves in a circular path within the galaxies. I was wondering whether galaxies also move in a circular path around something. Do galaxies rotate?

In images you see on the internet, large cosmological conglomerations of matter are shown in often gorgeous and variegated colors. Am I right in assuming that this is ALWAYS the results of applying false colors to show different wavelengths, or do any of them ever actually look that colorful...

Amateur with questions ;) It seems possible (probable even?) that some galaxies are moving away from us faster than light, which means we'll never get to observe them. That may only be a relative speed (like 2 cars doing 60mph in opposite directions, meaning 120mph relative to each other)...

I ask because I think I see two nuclei, can galaxies develop two nuclei without merging?

Hi everybody I just wanted to ask are all the galaxies in the universe visible by the light they send? In the other words are all the galaxies optically visible ?How do scientists predict the number of galaxies and do they understand the existence of other galaxies(very far galaxies) by...

When I first met the idea that light from an object that was moving away from us at superluminal speed would never reach us, it seemed quite reasonable. However, I seem to have developed a problem arising from the fact that light must always be observed as traveling at c, irrespective of any...

How do high red shift galaxies differ from low red shift galaxies? Dow e see significant differences? if so what ?

This might seem simple to some of you on here, but I have a question that's been bothering me, most likely due to my lack of understanding, not an actual problem. If two Galaxies, A and B, are traveling away from each other, say each at 3/4 the speed of light, does that not mean that if you are...

Many people, especially layman's would consider this to be a very chaotic event, however, isn't this really not true. From my understanding the astronomical structures within the galaxies actually do not crash/collide into each other. From an astrophysics standpoint isn't such an event a highly...

Can the speed at which galaxies separate exceed the speed of light?

I think I may have asked this before, but I don't think I received a reply that made sense, at least to me. Does the gravitational force between distant galaxies become larger and more significant due to their Relativistic Mass at high relative velocities and especially at luminal and...

Okay, so I understand that galaxies spin more like a frisbee than the solar system, and that there is evidence for a lot of non-light-emitting mass (such as gravitational lensing) but how would dark matter account for the difference in the spin of galaxies? Gravity still decreases inverse to the...

Why are solar systems and galaxies flat? I find it peculiar that astronomical clusters (ie: solar systems and galaxies) are arranged in a flat plane. Can someone explain why? I understand that: any solar system originates from a random cloud of dust and gas. This cloud will feel its mutual...

We are told the universe is expanding because galaxies are red shifted and that it is a doppler effect. Do blue shifted galaxies contradict the idea of an expanding universe?

I'm only talking about galaxies far enough away where the only significant motion between us and them is caused by the expansion of space itself. When we look at a faraway galaxy, does it appear to be as far away to us as it was at the time it emitted the light that we're seeing? Or does it...

This is probably quite a basic question but my mind has been ignited by the recent stargazing programs on the bbc so... Does every star have to be associated with a galaxy? For example, when looking through a telescope you see either individual stars or spiral galaxies - when looking at these...

If the light viewed through a telescope from one end of a specific galaxy takes, say, 100,000 years longer to travel to the eyepiece than the light at the closer end of the said galaxy, why isn't it skewed? Same goes with everything in the cosmos, why isn't more skewed the further back we look...

Does anyone know where to find a list or table of galaxies and their masses? I haven't been able to find one yet. One with their redshifts would be nice as well. Thank you very much.

Poisson errors for the distribution of galaxies?? Hi, I have some data regarding the distribution of galaxies of varying mass in different density regions of the Universe, from which I have a mass functions for each region. I would now like to introduce some errors so I can determine whether...

Why do the spiral arms of galaxies split or bifurcate? Is this due to a previous merger or some kind of current?

The idea is pretty far fetched, but would it be theoretically possible for an image of our galaxy millions or billions of years ago to be reflected or refracted via gravitational lensing back to our current position in space-time?

In the series "The Universe" Michio Kaku made a statement at the close that, as time progresses and the Universe continues to expand, that our sky would grow dark and depopulated of stars (at least that was the video graphic that accompanied his statement about the lonely end of our universe)...

When looking at the classifications of galaxies in the attached image, how do we explain the SB types - especially the SBc which has long arms that reach out radially before beginning to spiral? If these arms are spinning, then regardless of the speeds we measure, along the straight...

What would be the outcome of an elliptical medium size galaxy colliding with a dwarf elliptical? (I choose a dwarf elliptical basically because they are the most frequent type overall) Has this been computer-modeled? Is it thought to be a common type of collision? Any reference would be of...

If gravity acts on all angles of a mass, then why do galaxies appear to all have the same basic spiral shape with two relatively flat areas on opposite sides of it? Shouldn't all galaxies technically be big sphere looking shapes?

I saw an interesting video that showed the dark matter halo that exists around the milky way galaxy, the scientist described it as having a squashed beached ball sort of shape, which got me thinking. Is there any reason why galactic black holes might have something to do with dark matter...

I've been trying to locate an algorithm to model the distribution of stars in a spiral galaxy. Simple, I thought, I'll just Google it. However I quickly disappeared up my own black hole! What I'm looking for is a simplified algorithm I can use to model n stars in a galaxy of size x (for...

If galaxies aer expanding fast than the speed of light how are we able to see them. At the moment this expansion surpassed the speed of light shouldn't these galaxies dissappear or remain unchanged visually?

Hi, I'm wondering how S0 type galaxies form. I heard that it may be due to an end to star formation and a supposed resultant instability in the disk. Does anyone know about this or might be able to point me towards some relevant papers? Thanks :-)

Anybody out there with info? What part of the expandable universe have the galaxys been observed to be flowing to a pecticular direction. Been looking for information site on topic. Thanks

Just looking at a spiral galaxy made me wonder if there was an external resistance causing the spiral arms to fold in on the structure or if the gravity at the centre of the galaxy was pulling the arms back in on itself. Please let me know!

Does the Milky Way galaxy, along with several other galaxies in the Local Group, orbit about the centre of that Local Group, and does the center of the Local Group orbit about some other center, etc.??, or is it just the stars that orbit their galactic centers?