Starship Asterisk*

ThePiper wrote:
The evolution of a vortex/cyclone and a spiral galaxy: What's the common and what's the difference in the dynamic processes?
There must be some commons because of the similarity in the results.

http://en.wikipedia.org/wiki/Logarithmic_spiral wrote:

[b][color=#0000FF][size=115]Cutaway of a nautilus shell showing a logarithmic spiral[/size][/color][/b]

---

<<A logarithmic spiral, equiangular spiral or growth spiral is a special kind of spiral curve which often appears in nature. The logarithmic spiral was first described by Descartes and later extensively investigated by Jacob Bernoulli, who called it Spira mirabilis, "the marvelous spiral".

In several natural phenomena one may find curves that are close to being logarithmic spirals. Here follows some examples and reasons:

1) The arms of spiral galaxies. Our own galaxy, the Milky Way, has several spiral arms, each of which is roughly a logarithmic spiral with pitch of about 12 degrees.

2) The bands of tropical cyclones, such as hurricanes.

3) Many biological structures including the shells of mollusks. In these cases, the reason may be construction from expanding similar shapes, as shown for polygonal figures in the accompanying graphic.

4) The approach of a hawk to its prey. Their sharpest view is at an angle to their direction of flight; this angle is the same as the spiral's pitch.

5) The approach of an insect to a light source. They are used to having the light source at a constant angle to their flight path. Usually the sun (or moon for nocturnal species) is the only light source and flying that way will result in a practically straight line.

6) The nerves of the cornea (this is, corneal nerves of the subepithelial layer terminate near superficial epithelial layer of the cornea in a logarithmic spiral pattern).

7) Logarithmic spiral beaches can form as the result of wave refraction and diffraction by the coast. Half Moon Bay, California is an example of such a type of beach.>>

ThePiper wrote:The evolution of a vortex/cyclone and a spiral galaxy: What's the common and what's the difference in the dynamic processes?
There must be some commons because of the similarity in the results.

southofblock wrote:Well, don't really get it. How did the two collections start orbiting? (It is easy to ask questions, and have done little research). If the big bang was spherical, then all of the particles moved out radially(yes?), how did one particle start moving tangential to the others?

southofblock wrote:
Well, don't really get it. How did the two collections start orbiting? (It is easy to ask questions, and have done little research). If the big bang was spherical, then all of the particles moved out radially(yes?), how did one particle start moving tangential to the others?

Chris Peterson wrote:

southofblock wrote:Fine. What though causes the initial spin? That is, the center of mass of a clump of gas particles is vectored directly towards the center of mass of the larger, denser collection of particles. Where is the moment arm?

The center of mass of a clump of gas particles isn't vectored towards the center of mass of another particle collection. The two collections are in orbit about their common center of mass. That's the source of the spin.

http://www.universetoday.com/96344/oldest-spiral-galaxy-in-the-universe-discovered/#more-96344 wrote:

[b][color=#0000FF]Artist’s rendering of galaxy BX442 & its companion dwarf galaxy (upper left).[/color] [color=#FF0000]More typical galaxy from this period:[/color][/b]

---

<<Ancient starlight traveling for 10.7 billion years has brought a surprise – evidence of a spiral galaxy long before other spiral galaxies are known to have formed.

“As you go back in time to the early universe, galaxies look really strange, clumpy and irregular, not symmetric,” said Alice Shapley, a UCLA associate professor of physics and astronomy, and co-author of a study reported in today’s journal Nature. “The vast majority of old galaxies look like train wrecks. Our first thought was, why is this one so different, and so beautiful?”

Galaxies today come in a variety of unique shapes and sizes. Some, like our Milky Way Galaxy, are rotating disks of stars and gas called spiral galaxies. Other galaxies, called elliptical galaxies, resemble giant orbs of older reddish stars moving in random directions. Then there are a host of smaller irregular shaped galaxies bound together by gravity but lacking in any visible structure. A great, diverse population of these types of irregular galaxies dominated the early Universe, says Shapely.

Light from this incredibly distant spiral galaxy, traveling at nearly six trillion miles per year, took 10.7 billion years to reach Earth; just 3 billion years after the Universe was created in an event called the Big Bang.

According to a press release from UCLA, astronomers used the sharp eyes of the Hubble Space Telescope to spy on 300 very distant galaxies in the early Universe. The scientists originally thought their galaxy, one of the most massive in their survey going by the unglamorous name of BX442, was an illusion, perhaps two galaxies superimposed on each other.

“The fact that this galaxy exists is astounding,” said David Law, lead author of the study and Dunlap Institute postdoctoral fellow at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics. “Current wisdom holds that such ‘grand-design’ spiral galaxies simply didn’t exist at such an early time in the history of the universe.” A ‘grand design’ galaxy has prominent, well-formed spiral arms.

To understand their image further, astronomers used a unique, state-of-the-art instrument called the OSIRIS spectrograph at the W.M. Keck Observatory atop Hawaii’s dormant Mauna Kea volcano. The instrument, built by UCLA professor James Larkin, allowed them to study light from about 3,600 locations in and around BX442. This spectra gave them the clues they needed to show they were indeed looking at a single, rotating spiral galaxy.>>

southofblock wrote:Fine. What though causes the initial spin? That is, the center of mass of a clump of gas particles is vectored directly towards the center of mass of the larger, denser collection of particles. Where is the moment arm?

neufer wrote:I think that a binary black hole formed during the major merger event
and it picked up angular momentum with the later inflow.

neufer wrote:

Click to play embedded YouTube video.

winstond wrote:
Why does it start to spin and what keeps it spinning?

• Conservation of angular momentum

Chris Peterson wrote:

ddale51 wrote:
It seems to me that I detect a bit of a bar that forms in the center of the later galaxy. It's not very prominent but it kind of shows how maybe the bar can form on a larger scale, something I've been puzzled about ever since I first saw the bars in photos of spiral galaxies (though I'm hardly an expert in such matters). Is this a valid observation?

I agree. We're seeing a barred spiral galaxy form.

richiem wrote:
Sim doesn't run for me -- and they always have before. Is there something different about this one?

ddale51 wrote:Wow. Fascinating stuff. It seems to me that I detect a bit of a bar that forms in the center of the later galaxy. It's not very prominent but it kind of shows how maybe the bar can form on a larger scale, something I've been puzzled about ever since I first saw the bars in photos of spiral galaxies (though I'm hardly an expert in such matters). Is this a valid observation?

Boomer12k wrote:Two...Dark Matter is supposed to be what makes a galaxy appear to rotate as a single unit..as the Gravity is supposed to be very much beyond the mere edge of a galaxy, and caused by 90% dark matter, (that you cannot detect, so far)...as discovered by Carolyn Shoemaker, (she was examining the spectroscopy of galaxies)...

Also we bob up and down in the galaxy, (gravity wave?), as on Dec. 21st, 2012 we are going to cross the galactic equator.

Three...The simulation does not run out of material...more and more material seems to just generate and fall into the galaxy, was Fred Hoyle correct?

--- I am assuming that the simulation is much larger than just this one area. (As I see other material go by)...But in the real universe, in our own galactic area, while we do have smaller satellite galaxies and such, I don't see them coming in and joining like cotton candy, at the edges like it appears to be here...our galaxy seems more...constant....I think is the word I am looking for...we don't see "extra galactic material" falling into M31, from the sides, for instance...maybe it just represents dust and gas, and not star formation...lot of things the article does not explain, but hey, pressed for space, I guess.

Margaretta wrote:
Do the particles of two merged galaxies speed up, maintain speed or slow down?

ems57fcva wrote:
I'm not very impressed by this simulation. No central bulge (and at least an insignificant one), no dust lanes, and no bridges between the centers of the galaxies after a close encounter. So I see there as being a long ways to go here.

neufer wrote:Orin possibly

ThePiper wrote:

neufer wrote:Velocities should be roughly constant regardless of distance from the center.

@neufer
Are you sure? In this case we would have a homogenous disk. But We have spirals because of the speed-gradients between the center and the outer areas.

Vincent Pinto wrote:

while time is shown in billions of years since

None of us who read this or those who posted the original quote were there then to so professorially say it took that much time.

• Orin possibly

Vincent Pinto wrote:
More importantly, the assumptions used to make the statement in the quote are non-verifiable assumptions, and therefore to posit the notion it took that long is certainly not science. It would however most emphatically constitute a belief. Since the same vein, there are some people, I'm told, who believe in a flat earth.

http://supercom.org/oldest-known-galaxy-detected/433195/ wrote:

[b][color=#0000FF]Oldest Known Galaxy Detected[/color][/b]

---

<<Astronomers using the Hubble Space Telescope have discovered what scientists think is the oldest galaxy so far detected, a galaxy so far away that the light from it has taken 13.2 billion light years to reach us, here on earth. It is so old that it is thought to be one of the earliest galaxies ever formed, just 480 million years after the Big Bang.

Scientists believe that galaxies started to form 200 to 300 million years after the Big Bang as new stars clustered together, then evolved into baby galaxies then eventually into large galaxies that we see today.

The newly detected galaxy was discovered using Hubbles’s recently installed Wide Field Planetary Camera 3 combined with Hubble’s eight feet wide mirror. The galaxy is calculated to be small compared to our own galaxy, the milky way, at one hundredth its size.

Astronomers and scientists are looking forward to the launch of NASA’s James Webb telescope sometime after 2014. This will enable observers to look back even further in time to when the galaxies were just forming.>>