Galaxies Definition and 424 Threads

I know it probably looks like a completely stupid question.. But I can't find the answer. Hopefully you all can help me out here. Essentially, all galaxies are moving further apart, from each other.. each spot in the universe is said to have the same effect of everything moving further apart...

I have read some information, from various sources, pertaining to the orbital speed of stars about the center of galaxies, and some of it appears to be conflicting. Some sources claim that the stars closer to the galactic center orbit faster, while those father out, orbit slower. This of...

What is it that makes a galaxy rotate, is the gas it was formed from rotating?

Might galaxies in filaments http://pil.phys.uniroma1.it/twiki/bin/view/Pil/GalaxyStructures" for spirals? An extented flattened curve means more DM further out; the original discovery route of DM.

So, as you may or may not have known there's an interesting correlation between galaxy brightness and it's color. Basically, the brighter the absolute luminosity of a galaxy the redder it tends to be when compared to galaxies of the same type. I say "tends" because randomness does give the...

It's not often I'm shocked in a positive way, but could this be true? I forum where science "discussions" are at least consistantly of higher caliber then "evolution sukz because bible says so, lol"? I'm sorry if my shock confuses and annoys others on this board but imagine traveling through...

I'm looking into galaxy rotation curves and I was wondering where I can find a good (preferentially recent) overview of measured galaxy rotation curves (refereed journal article, good website, arxiv ..). Further I was wondering how far out (from the galaxy center) one can measure rotation...

Sprial galaxies - Are the axes of rotation of the purely random? This article: http://adsabs.harvard.edu/abs/2005astro.ph.11680T suggests the axes are preferentially aligned with cosmic voids. precis: Disk galaxies' axes should be highly inclined relative to the plane boundary of...

How probable is this? 100 Billion galaxies, there has to be at least one other civilization out there, no?

Our perception of what a galaxy looks like is inherently skewed given that the immense size of the galaxy itself provides a lopsided picture. If viewed from any angle other than directly head on, the closest point of the galaxy will be a much more recent picture than that of the far end, by...

What is a typical distribution of mass in a typical spiral galaxy. I understand most is in the centre, but how much? How much in the outer regions? Can anyone point me to graphs or tables? Much appreciated.

http://space.newscientist.com/article/dn12233-baby-galaxies-sighted-at-dawn-of-universe.html great. (of course must be cautious with first report and wait to see if confirmed...but looking good) galaxies from when the universe was only half a billion years old SciAm has this...

I just posted about what is termed "apparent superluminal velocity of galaxies" and gave a website of an article written by Prof-Dr. L. Schatzer, which was said to be not "main stream". My posting was moved because it contained this website that was not considered " main stream" and no...

As I understand it we can use the principle of parallax to measure distances to objects within 400 light years from Earth. So how are the further stars and galaxies calculated?

I was wondering, if dark matter (DM) halos are spherical in nature and increase in density as a function of distance from the galactic core, why does the density drop off so suddenly and why would stars on the edge of a galaxy feel an inward pull? To elaborate on the 2nd question, if DM...

Today's Astronomy picture of the day is visually appealing as well as scientifically revealing. http://antwrp.gsfc.nasa.gov/apod/ap070516.html The text points out that the foreground galaxies are tan in color while the background distorted ones are blue. Does anyone know why this should be...

hey i need help! We are doing a lab on the above title and I have no idea how to do it. So there are few questions i wanted to know to ace this lab. lol i will really appreciate it if someone can help me. - Describe the differences between the two sets of data. Is the observed speeds...

Hello, Could you please tell me roughly, how many galaxies have been observed? Thank you, Glynis

I found an interesting explanation for rotational speed of the galaxies in the below link at section 7.1 http://www.ag-physics.org/gravity/ Can anyone comment on this ?

We see galaxies as their light reaches us after billions of years of travel. But if the Universe itself is expanding, there should be an indefinite number of galaxies whose light not only did not have enough time to reach us, but will never reach us due to expansion. Perhaps the mass of...

Are there large scale lagrange points between gravitationaly bound galaxies? ie a small galaxy that orbits a larger one, or even points where gravity is null between near large bodies

Just from general ideas gained over time I am under the impression that structure in our universe started with slight anisotropy in the CMBR. That slight fluctuation is gradually compounded and leads to structure, i.e. galaxy formation. Building on that idea I am concluding that black holes...

Do you think there are more stars in our Milky Way galaxy, or galaxies in the observable universe?

this might be a dumb question. but how come we can see objects that are 9 or more billion light years away from us? seeing as the universe is only 14 billion years old, and nothing can travel at the speed of light... then how can we see objects that would have taken 6,7,8 + billion years to get...

Two identcal spiral galaxies A and B with equal but opposite momenta a and b are merged to form a resultant galaxy C with a net linear momentum c. Which is true? a) c>b b) 0<c<b c)c= abs(b)+abs(a) d) c=0

Because if would seem to me, that planets suffer relativly little disturbance from these collisions, that is, they're not pulled away from their main star, by other massive objects passing nearby. (Or in most cases they're not) During the 4 billion year history of our solar system, the Earth and...

How do these come about, also what are the leading theories behind the formation of these objects?

http://en.wikipedia.org/wiki/Binding_energy#Mass_Defect But the opposite is true for galaxies! Quarks too! Their mass appears to be larger than their constituents as well...

I have just listened the cosmologist Hubert Reeves on a radio broadcast. He says that there are clusters of galaxies, superclusters of galaxies, but he also says that there are no super-superclusters of galaxies. My question is the following: do we know why there are no super-superclusters...

I don't know if this belongs in Astronomy or Cosmology, mods, move it if you see fit. As far as I'm aware the idea of Dark Matter was introduced because of the rotation of galaxies. Closer to a galaxy's centre matter should move faster because of the stronger gravitational pull, and further...

Can anyone point me to some good links about the our current understanding of quasars-in particular why they are so far away? and also how they are related to black holes in galaxies? thanks

Is this true and why?

Why is it that for the most part, all orbiting planets in our solar system orbit together on the same 2D plane. The same can be asked for the disk shape of all of the galaxies. (sp everywhere) Thanks, -scott

Could the supermassive object in the Milkyway be a SGR post mortem? I tried to fix the title (I realized it contradicts what I posted), but I couldn't (retarded is that.), and I can't even delete my own thread, so here's the new title: Could the supermassive object in the Milkyway be a SGR...

why is it that galaxies are placed the way they are in our observable universe? as spirals of solar systems with empty space between them? isn't it a concept of the big bang theory that, the universe was created from a point of singularity? And at an instant, all matter was ejected from that...

Sorry if this is a lay question, here it goes: Consider that on Earth we observed two galaxies, one directly above the north pole, the other directly above the south pole (aka. opposite directions). When we measured the redshifts of these galaxies we concluded that they had recessional...

Obivously, the direction of the rotation of a Spiral Galaxy depends on the vantage point from which you look at it. From Earth, do all Spiral Galaxies rotate in the same direction? Or, because the universe is so vast, the rotation direction is irrelevant and has morre to do with prior collisions?

man, after a long time I've got a question! Einstein proved that the universe is expanding but the the galaxies aren't expanding themselves, right? and I've also read an example given by one of the members saying that if u keep 2 or 3 coins on a rubber band and stretch it, the fabric of...

Why does the face on surface brightness profile of spiral galaxies follow an exponential decrease with incresing distance from the center? Why is it exponential as opposed to linear or some power law? seems like 'e' shows up a lot. I know it is an obervational fact that they exhibit this...

how can this be explained?

from http://stardate.org/radio/program.php?f=detail&id=2005-12-08

please correct me if this is a misconception that i have about "visible Universe" . Is true or not that in the limits of the universe visible to us , galaxies move faster than light and because of that we cannot detect it, and that this occurs continually, ( i mean more and more galaxies every...

I watched a tv programme recently in which it said astronomers had found that every galaxy had a supermassive black-hole at its centre. What I found curious was the finding that each specific black hole always made up 0.5% of the mass of the galaxy it was located in. There is clearly an...

Blue-shifted Galaxies Why are the blue-shifted galaxies located pretty much in two directions in the sky about 180º apart? I got a list of blue-shifted galaxies from the NASA/IPAC EXTRAGALACTIC DATABASE (NED), http://nedwww.ipac.caltech.edu/index.html, and sorted them by their velocities...

Black holes and galaxies! Blackholes and galaxies Recent studies show that black holes or rather supermassive black holes are found at the centre of most galaxies.Is there a connection between that black hole and the formation of the galaxy itself? Could it be that there was a neutron star...

I read about this somewhere (can't remember) where it stated that the rate of starbirth has decreased as opposed to when our galaxy was younger. So if it is decreased is it still decreasing and if it stops completely (in any galaxy) does the galaxy itself just "die"?

This is my first post on this message board. So if this message does not represent itself the way I am trying to express it, I apologize in advance. Based on an article in Scientific American March 2005 addition, it stated that galaxies recede faster than light. "The recession of a galaxy...

According to the Raisin pudding theory all raisins (galaxies) are to be receding from one another, so why is it that there are exceptions for example the Andromeda Galaxy that is heading towards the Milky way at 50 kilometers a second? and other such galaxies merging together if they are to be...

http://arxiv.org/PS_cache/astro-ph/pdf/0502/0502385.pdf No kidding. Would anybody here like to hazard a guess at where this "reddening dust" lies on the path between the z~6 galaxies and our vantage point? If the "reddening dust" is very ancient and distant, I would be interested in hearing...

When I look at pictures of swirling galaxies. The swirling patterns look very much like clouds swirling around the eye of a hurricane. This would imply that it is space itself that is being pulled toward the vortex of the galaxy and the stars are tagging along. Just like a hurricane pulls...