Thread: Galactic Rotation

Greetings all
I am an amateur that LOVES science.
Most of all cosmology I guess.
ANyway, I was wondering if anyone has any thoughts on galactic rotation.? One of my favorite facts ,is that a woman discovered that stars @ a galaxies edge rotate @ approx. the same speed as stars closer into the core. It was conventional wisdom that those at the edge would rotate faster, but that has been proven false.
What are the mechanisms responsible, and do modern computer generated collisions between galaxies take this into account?


Also,.. not to step on any toes,, but since I will be using these forums to try and expand my horizons, untill I can learn who is reasonable and who is not on my own, could someone post the names of those members who are most reasonable, and :? those whom I might be wasting my time trying to decipher.
TY

Originally Posted by Mek

Greetings all
I am an amateur that LOVES science.
Most of all cosmology I guess.
ANyway, I was wondering if anyone has any thoughts on galactic rotation.? One of my favorite facts ,is that a woman discovered that stars @ a galaxies edge rotate @ approx. the same speed as stars closer into the core. It was conventional wisdom that those at the edge would rotate faster, but that has been proven false.
What are the mechanisms responsible, and do modern computer generated collisions between galaxies take this into account?


Also,.. not to step on any toes,, but since I will be using these forums to try and expand my horizons, until I can learn who is reasonable and who is not on my own, could someone post the names of those members who are most reasonable, and :? those whom I might be wasting my time trying to decipher.
TY

science view; galaxy take on various forms from dwarf to cluster and in various ways forms of spiral, which our milky way is one. NASA as some very good images of all these, the formations of stars and the results of deaths. they are thought to form in two ways, matter flattens into a kind of a pancake, gravity pulling matter dense and at some point a fusion action will take place one by one with in this pancake. the process at this point not visible as fusion is within a unit dust and debris is shading view.
the fusion process reaches an explosive point shedding the debris, light and the star become visible. some thing this misc. stuff becomes the moon and planets of those stars. this same process could be done randomly from collected matter compressing. the result would find another star and a process has begun. all this can be google, galaxy or star formation.

your in a area where who is correct or wrong may not be possible, since most is speculation and accepted theory are sometimes inseparable. that is accepted theory, may appear speculation. i would suggest a day or two on the web; forming some opinion and testing one on the forum. as to individuals, most authoritative opinion is obvious and the moderators seems informed. i am neither but do have opinions.

Welcome to our forum, It would not be a good idea for any existing member to to suggest any other member is, shall we say 'unscientific' in their post's it may be that some are good at some topics and less well off in others. But I think you'll pretty soon find out.

Most of us will help, I don't think there's anybody who deliberately set's out to mislead. You could try posting a topic with which you already know the answers and see what reponse you get..


Jackson33,

Oh yes, he Does have opinions.. 8)

mega; my post was in line. i did not say he didn't have opinions, but if one was there i missed it. the thread is typical of the many with real interest and the desire to be involved and/or learn. i did say i have opinions, but gave none and you know very well, that topic is mine. i have spent most of this day with you on Galaxy formation but gave only a brief summary of accepted views. Not mine and not my style.

It was a reference to your last line, I was referring to you, humorously reinforcing what you said.... should have worded it better...

Originally Posted by Mek

It was conventional wisdom that those at the edge would rotate faster, but that has been proven false.
What are the mechanisms responsible, and do modern computer generated collisions between galaxies take this into account?

The consensus is that there has to be unseen mass to account for the equality of rotational speed. What is this unseen mass? Again, the popular view is that it is the 'dark matter' that is responsible.
What is dark matter? That is one of the big questions facing astronomers today. Current theory suggests that 90% of the mass in the Universe is not of the familiar baryonic matter - protons, neutrons, etc. Thus this dark matter may account for anomaly in galaxy rotation rates.
An alternative view is that the dark matter is composed largely of brown dwarves: stars whose mass is so low that they didn't quite make it to full time fusion furnaces.

My own rule for sorting the wheat from the chaff is simple. (That, of course, does not mean it is right. ) If they write logically and clearly, with well structured arguments and passable grammar and spelling, then their ideas are worthy of further consideration.
On this basis you will readily see whose contributions here I value, and those which I treat with a measure of suspicion.

Roger that.
While I realize it might have already been taken into account, I view our own solar system as an analogy to the galaxy as a whole. IOW, our solar system is surrounded by the ort cloud. I dont believe we have any idea as to the true mass of said cloud. Could it not be that each galaxy is surrounded by an "ort cloud" thereby providing a substantial boost to mass? I also realize most everything I post here will be musings, since I am not a scientist per se,but since cosmology as a whole is WIDE open, it couldnt hurt to ponder and maybe learn a thing or two.
ps. the brown dwarf angle is similar to what I thought of, but better since while many may think of brown dwarf as low mass, obviously theyre not,Jupiter isnt "low mass" , and its less mass than a brown dwarf.. right?

Originally Posted by Mek

Roger that.
While I realize it might have already been taken into account, I view our own solar system as an analogy to the galaxy as a whole. IOW, our solar system is surrounded by the ort cloud. I dont believe we have any idea as to the true mass of said cloud. Could it not be that each galaxy is surrounded by an "ort cloud" thereby providing a substantial boost to mass? I also realize most everything I post here will be musings, since I am not a scientist per se,but since cosmology as a whole is WIDE open, it couldnt hurt to ponder and maybe learn a thing or two.
ps. the brown dwarf angle is similar to what I thought of, but better since while many may think of brown dwarf as low mass, obviously theyre not,Jupiter isnt "low mass" , and its less mass than a brown dwarf.. right?

we do have a pretty good idea on the actions in our solar system. the inner planet mars, rotates at nearly 50 miles per second. the rest get slower and earth moves at 29.8 mps (70k per hour), Jupiter at 13.1 mps down to Neptune at 5.4 mph and if you count Pluto it rotates around the sun at 4.7 mps. this I'm told is why each is at the distant it is from the gravity pull of the sun. that is if Jupiter slowed to exactly our speed we would both orbit at the same distance.

the galaxy has no one source to determine the speed of what is in rotation and opinions on the cause and speed vary. our sun is about 1/2 the distance from the center to the outer stars and we travel around the center once every 250 million years. keep in mind the galaxy also is traveling.

black holes are thought to be mega stars or giant stars 20-25 times ours, that the centers have depleted fuels (hollow) and mass falls toward a center, self creating massive gravity in very small areas. many feel this is a process in action and the BH evaporates in time.

when a star is forming, giant masses similar to Jupiter, but thousand of times larger the first emissions of fusion are with in and light is there but inside what we could see. at some point it explodes into the final form and all the dust debris and lose matter in discharged away from this unit and the star or light emissions are sent. since light or those waves or beam of light travel at 186k mp second, they will be seen by us when they have traveled our distance from from in light years.

this is OPINION; our vision is based on a portion of an electromagnetic scale and since light emissions are on this scale and our vision is determined by wave length, some think and i do, that the light from forming stars, dark matter, is emitted but at levels below our limits of vision. kind of like some light should get through regardless of our much surrounds this forming star.
if you draw a picture of a galaxy on a piece of paper, center the paper on a nail and rotate the paper, everything moves at the same speed, nothing ever changes position and any speed would be related to the total movement of the entire unit. the universe thru space.

Originally Posted by jackson33

if you draw a picture of a galaxy on a piece of paper, center the paper on a nail and rotate the paper, everything moves at the same speed, nothing ever changes position and any speed would be related to the total movement of the entire unit. the universe thru space.

Sorry, I disagree.

It will all rotate at the same RPM, but the outer edge of the paper will be travelling faster as it has a larger circle to go round in the same time.

Jackson, ty for the reply,but Im aware of a vast majority of the basics. I was refering to our ignorance as to the true extent of the ort cloud. WHether we have over or underestimated its size and composition, either way, its mostly conjecture. Its obviously not easy to spot bodies larger than pluto, yet they exist, and a host of other observations indicate there is a lot of matter out there. I prefer to visualize it as an electon haze with the sun as nucleus.

Mega, I agree, I think,.
The work I saw explained it like this. If you take a standard model of the solar system, inner planets rotate faster around the sun, the closer the orbit.
A galaxy's stars rotate around the central axis of the galaxy at the same rotation..
Yes , we agree, same number of rotations.
Anyway, thats why I brought it up, it speaks right at the heart of what we dont understand.
I need to take a look at the black hole discussions since Ive had some interesting thoughts as to whats actually driving the expansion,and just what happens to all that matter and energy when it crosses no mans land. 8]

Originally Posted by Megabrain

Originally Posted by jackson33

if you draw a picture of a galaxy on a piece of paper, center the paper on a nail and rotate the paper, everything moves at the same speed, nothing ever changes position and any speed would be related to the total movement of the entire unit. the universe thru space.

Sorry, I disagree.

It will all rotate at the same RPM, but the outer edge of the paper will be traveling faster as it has a larger circle to go round in the same time.

i knew you would. no nothing is moving. only the paper or in this case the galaxy. each drawn object is still not moving and any speed is concluded from what passes the unit.

i understand for a distant object from a center to rotates in time with one closer the outer has to move proportionately faster. but if nothing is moving, there is no rotation then there is no speed of any object and the appearance of movement is in the observation of whats around the object or maybe even from with in. since its contrary to all i feel is in a formation of a galaxy it was submitted as food for thought. probably should have left nail out and walked the paper.

thought you or ophiolite would come back first on the BH, thing.

Well you'll be pleased to know the answer is up for grabs, the dark matter solution has errors when the 'adjusted' characteristics of darker galaxies come into play. So anything goes!

I hate to do this, but could you guys rehash a little of what you both just said.
sry
no movement?
darker galaxies?

It is thought that 'dark matter' existing within the spiral arms provides gravity outside the central 'bulge' which (soem say) would account for the rotational anomoly of the star rotation rate. However, in darker galaxies (where there is not so much 'light') the calculations fall over.

Here's a link you might like to look at.

http://en.wikipedia.org/wiki/Galaxy_rotation_problem

that link will effectively remove me from the discussion for a wee bit. lol
ty

mek; sorry, i have no idea at what level a question is asked. if above my level, i tend to read, digest and move on. below mine and to a person interested in science i go to basics and judge later to keep involvement.
since my object is also to learn not teach.

on BH, i would like an opinion not in the books. to me, these and galaxy formation in general defy some rules of gravity. or at least some thing is missing in the formula. i like the word friction but that turns off the learned. BH on the other hand could be an internal force driving the circulation.


mega; normally i don't respond to dark matter topics, since I'm not sure what any one person is talking about. some think anything unseen is dark matter, others gaseous objects and some some form of dust. i heard a reference to stars in formation and am familiar with that version and responded. also there are those that feel this process is emitting light just not seen.

this borders on SF, but i wrote a piece recently suggesting the evolution of mankind could have reduced our EMS vision senses, to give us darkness, for reason (sleep and/or confusion) from the level of seeing all or more of now unseen light and possibly even wave lengths.

i fail to see how additional matter seen or not can influence galaxy rotation or the spiral effect. if there was one galaxy that was that much greater than all the others, this may be, but formation seems to tail off and end in each and at the same general size.

Originally Posted by Mek

I dont believe we have any idea as to the true mass of said cloud.

If this is hyperbole, OK. If it is an objective statement, then I disagree strongly.
The existence of the Oort-Opik cloud was predicated on the regular appearance of short lived long period comets. The frequency of such visitors permits a calcualtion of the probable size (to an order of magnitude) of the Oort-Opik Cloud.
More recently F.E. simulations of the formation of the solar system provide estimates of the probable size (and composition) of the cloud. I believe that simulations by various researchers, using different assumptions, produce comparable figures.

You also made reference to Pluto sized bodies. I wonder if you are confusing the Oort-Opik cloud with the Keuper belt?

Kuniper, ort cloud, I forget which one is the greater distance from the sun, but I was refering to the total mass of what is out there. I understand the calculation based on our limited observation of comet period, but an order of magnitude is a good place to start for an underestimate.
Just throwin an idea out there. The scientific mind has been subjected to earth centric and helio centric prejudices , so if there is a problem of missing mass, I thought to look in places where we are discovering additional mass that we didnt know of till recently.