Galaxies Definition and 425 Threads

This is a significant discovery that something is fundamentally controlling and ordering the properties of spiral and disk gaseous galaxies. Elliptical galaxies have no gas and no star formation. The question is not only what but how is the unknown parameter controlling spiral and disk galaxy...

Hi everyone, this is an interesting question i can't tackle as i don't really know where to start... Spiral discs are found to be composed of both a thin and a thick disc population. One way that a thick disc can be created is through the merger of minor satellites. Consider the energy of a...

The other day I ran across the idea that galaxies lose mass due to their radiating. Before I heard this I assumed that galaxies became more and more dense as their lives wore on. Such that the gasses became gas giants and stars, dust became asteroids, planets, and moons, and the fusion in...

Are galaxies fairly evenly distributed regardless of which direction we look out from? Also are the oldest stars and galaxies that we can view also relatively evenly distributed in all directions? I am asking because assuming that we are not in the center of the universe, I would imagine...

If the galaxies are drifting farther apart at close to light speed then why are we bothering to try to go to other galaxies?

Homework Statement I am trying to calculate, from their redshifts, the speed at which each of the following galaxies is moving away from us. Give your answers in both km/s and as a fraction of the speed of light. The galaxies are: Galaxy 1: Observed wavelength of hydrogen line is 659.2...

I'm confused a little bit by this and have a few questions. I wasn't sure where to put this because it's kind of a relativity question (time dilation) and a cosmology question combined. From what I understand, all galaxies are moving away from us. But isn't the Andromeda galaxy eventually...

I'm sure this is a stupid and/or already asked question. But I don't do astronomy. If every galaxy has a black hole, and black holes suck everything in, does this mean that our galaxy is being slowly destroyed by black holes? (Everything just keeps getting sucked in) And if so, are we going to...

Does the direction a galaxy is spinning have anything to do with some cosmic Coriolis effect?

Ho :), I would like to know how exactly stars and galaxies are spread out throughout the universe. Are stars only found within galaxies? How many stars are without any planets? Whats the average number of planets in a star with planets? Whats the maximum/minimum number...

I read that the distribution and proportion of dark matter to regular matter is different for regular-size galaxies and dwarf galaxies. Could you guys elaborate on that?

According to Einstein, the Big Bang theory did not make sense because he said if you mapped the paths of the galaxies and stars back in time they would not collide at a singularity at the center of the universe, they would miss each other. Since many people accept the Big Bang theory, has it...

Homework Statement if the intrinsic brightness of a class of radio galaxies fades as the universe ages, such that those that we see further away are brighter, having a linear increase in luminosity with distance r, what would be the slope of a graph of log N(s) versus log S for these objects...

Is there anyway to determine a galaxy's distance by figuring out its actual size (or the visual portion) and then reverse triangulate to us? All I hear is about standard candles as the source for determining galactic distances - either Cepheid variables or Supernovae. We have of course...

Governato et al. have offered a solution to a long-standing puzzle about structure formation. Published in the current issue of Nature. http://arxiv.org/abs/0911.2237 Dark matter dynamics (esp. with supercomputer simulations) has already explained a lot about structure formation. For an...

Galaxies traveling faster than the speed of light?? 1st off, Hello to everyone on the board. There are some very interesting ideas/posts. I watched a Youtube video titled "The Hubble Ultra Deep Field in 3D" (beautiful video by the way) It states that some galaxies are moving away from us...

Hello This is my first post and excuse me I'm a bit dim (hence my username). So, I've had this question rattling around in my head for a while... There are a lot of pictures of so called "Spiral Galaxies" and according to Wikipedia the taxonomy of galaxy shapes was described by Edwin...

I was browsing sites on the galaxies in response to another thread, and I encountered a rather unusual picture of ESO 510-G13 Hubble Photographs Warped Galaxy as Camera Passes Milestone http://hubblesite.org/newscenter/archive/releases/2001/23/...

I have read on a NASA website amongst other places that "Many astronomers believe that Seyfert galaxies and high-energy quasars are basically the same type of objects, but we are simply viewing them differently". But on the same website it also says that "by measuring their redshifts, we find...

Given that the universe is expanding and galaxies in general are accelerating away from each other, I would assume that galaxies appearing in the Hubble deep field at a distance of 12 or 13B light years from us should be much closer to each other than is typical for galaxies today. Is this a...

Im aware that the planets in our solar system all orbit the sun on the same plane. and if we look at the milky way all the stars are aligned on the same plane. if we go out one further (ie to look at galaxies) , I am wondering if the motion of galaxies and how they are aligned has any structure...

Hi, my knowledge in astronomy is very little. So pardon me if my thinking becomes stupid. All the galaxies are moving away from one another with acceleration. The more distant they are, the more acceleration they have. Acceleration implies increase of velocity. So my point is that if the...

I've read a little about how rotation curves for galaxies are calulated and my question is since rotation curves of galaxies are calculated using the center mass of a galaxy from a star's orbit would the effect of stellar mass extending beyond the star's orbit that is directly behind the...

Is it possible that a far off galaxies that we are unable to reach are made up of anti-matter? How do we know that they are made up of matter?

Homework Statement The Andromeda galaxy is at a distance of 2.1 X 1022 m from our Galaxy. The mass of Andromeda is 6 X 1041 kg and the mass of our Galaxy is 4 X 1041 kg. (a) Gravity accelerates the galaxies toward each other. As reckoned in an inertial reference frame, what is the...

Hubble discovered that galaxies are moving away at each other at a rate, today physicists believe that this rate is increasing. I've read about galactic collisions, and that the Andromeda galaxy will eventually collide with the milkyway. If the galaxies are moving away from each other, then how...

Planets <--> solar systems <--> galaxies Have planets been observed outside of solar systems, or solar systems outside of galaxies?

With the Hubble telescope now able to see back in time by as much as 10 billion years, can anyone explain the path of the photons from very old galaxies entering the HST during the last 10 billion years and particulary where they were around 4,500 million years ago?

Hi, I'm a writer and I've just started researching a story about astronomy. I'm not a physicist (actually I'm a biologist by trade) but I really want to get the science right. I know a lot of work has been done lately with things like the Sloan Digital Sky Survey but I was wondering what...

It is often stated that observation of the most distant stars inform us about the early universe because the light we observe now was emitted from the stars when the universe was young. In fact this is a quote from space.com: "The universe is about 13.7 billion years old. Light reaching us...

12 August 2009 My question relates to the search for antimatter in the cosmic space. As far as many laymen know, the composition of the material ingredients of galaxies is detected through spectroscopic analysis (i.e. through the analysis of the electromagnetic waves emitted). Considering...

rough estimate, how many galaxies in the visible portion of the universe? Just curious.

hi folks, maybe somebody can help me with this: According to the standard theories of cosmology, the universe started with a "Big Bang" about 14 thousand million years ago and has been expanding ever since. Yet there is no centre to the expansion; it is the same everywhere. The Big Bang...

Accelerating galaxies? If Gravity is constantly pulling galaxies toward each other, why are they accelerating away from each other? ::::::::::::::::::::::::::::::::::::: In Love Prys die Heer!

http://en.wikipedia.org/wiki/Andromeda_Galaxy" http://en.wikipedia.org/wiki/Triangulum_Galaxy" http://en.wikipedia.org/wiki/Messier_81" I've only seen M31 with the naked eye. If I look at M33 through my 8 times 40 bino, then it doesn't look like something I could ever see with...

I am not a physicist but I am an engineer who uses your science. Cosmology is fascinating and what I know about it is not much and much of which I've learned from programs such as NOVA and from a 1960 college course in Modern Physics. My question is from some information I read or heard...

I am curious, partly because of a test tomorrow, about the difference between peculiar and irregular galaxies. Pretty much my current understanding is that peculiar galaxies are formed from gravitational interactions between/among galaxies, and irregular galaxies are just different. From the...

How old was the universe after the big bang when galaxies started forming?

I've read that Dark Energy was invented to explain why galaxies really far away are moving away from us faster than ones closer to us. Now I'm sure they did this, but did they take into account that if they look at 2 galaxies A and B. Galaxy A is 500 million ly away and B is 5billion ly away...

To construct your very own unlimited energy supply, go down to the hardware store and buy yourself a nice long and strong rope. Then tie one end to an electrical generator and the other end to some other galaxy. The expanding universe should take care of the rest. Is this a true perpetuum...

Couple of questions here; I know they may sound dumb but here they go. I'm "new" with some questions, so be gentle. 1.) So, if a black hole has enough gravitational pull to pull in stars and what nots, and nothing can pull away from this force once it is to close, its consumed by the black...

I was wondering, when we look at galaxies head on through a telescope, do we get a distorted view? What I mean is for example if the core is aimed directly at us so we see the galaxy from the top then the light of all stars is pretty much the same age. But in the galaxy itself there's a...

It takes a continuous input of energy to spin, otherwise things would fly apart or stop spinning. So why do large macro objects spin, and continue to spin?

why is the temperature distribution of hot gases inside galaxies evidence for dark matter and why is Type 1a Supernovae evidence for dark energy

The discs of all large galaxies show a "flattening" of their discs where the material at the outer edge of the discs rotate at the same rate as the material near the center of the galaxy. The explanation for this is that the galaxy must be embedded in a halo of invisible "dark" matter which, I...

Hey! Has anyone else heard of filaments of galaxies? Apparently galaxies fall onto galaxy clusters by first falling onto 'strings of galaxies' that feed the accretion. These filaments are supposed to connect galaxy clusters that are very close spatially. I think this has something to do with...

I'm looking for reliable informations about the % numbers of galaxies in the whole visible universe, by Hubble type (S, SB, S0, E, Irr), for a T0 time slice (i.e. today). Of course, looking far away into space means we're also looking far away into the past, so distant galactic populations (by...

I understand Einstein’s theory of relativity quite well but I keep thinking about different things and getting confused. All galaxies are moving away from us and the further away are moving faster. I know nothing can move faster than c but if there was a galaxy far enough away should it not be...

Hello, I have a question concerning general relativity. (go easy - I have only knowledge from general consumption physics books). Something curious I have been thinking about requires an explanation as to where I am incorrect in my thinking: My understanding is that, as something moves...

Would a galaxy 7 billion LY away appear to be twice the expected size (angular size) as a consequence of the expansion of the universe? (Assuming the universe is 14 Billion years old). My math says yes. But of course, I am just using trig and geometry. Just curious.