Questions tagged [spiral-arms]

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Spiral Galaxies

I only have a very, very, basic understanding of linear motion, much less so of circular motion. What I can recall is my book telling me if you spin a stone tied to the end of a string and the string ...
Agent Smith's user avatar
3 votes
2 answers

Does the observed sky change when solar system passes through a spiral arm of Milky way?

According to density wave theorem, some other questions here [and my basic understanding from it] the spiral arms of an spiral galaxy are fixed regions of space around it with higher gravity, where ...
Tirdad Sadri Nejad's user avatar
5 votes
1 answer

Is it theoretically possible to see a spiral galaxy head on, and side on, if there is a convenient gravitational lensing effect?

I was thinking this when I heard Professor Mike Merrifield say something to the effect of "unfortunately we've never seen the same galaxy side on and head on, so we can compare notes on our ...
Rabbi Kaii's user avatar
5 votes
0 answers

Did the density wave theory for spiral arms take account of this phenomenon?

I came across this link. In it the author speculates that in the outer region of a galaxy, the spiral arms overtake the stars, and vice versa for the inner region. That means there must be a middle ...
longtry's user avatar
  • 403
1 vote
2 answers

Fate of lone spiral galaxies?

I know Hubble's galaxy classification scheme and the bifurcation from elliptical galaxies into two types of spiral ones. I am also aware of different theories on how spiral galaxies form e.g. through ...
B--rian's user avatar
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3 votes
0 answers

Is there a minimum size for a galaxy to have spiral arms?

Is there a minimum size or mass for a galaxy to present spiral arms? I don't remember many small galaxies with spiral arms. Does the mechanism responsible for producing spiral arms no longer hold if ...
Elismar Lösch's user avatar
20 votes
1 answer

How small can a spiral galaxy be?

The smallest observed spiral galaxies I can find are NGC 2976 and NGC 4605, both with a diameter of 20 kly, but I don't have anything like an exhaustive source to search. I've also found a mention ...
Elukka's user avatar
  • 301
46 votes
2 answers

Does the sun cross other spiral arms in its movement around the galaxy's center?

Today, released an article that states: [...]. In questo suo peregrinare galattico, il Sole ha attraversato anche i due bracci della Via Lattea Perseo e Centauro. "Sono zone di alta ...
Patrick Trentin's user avatar
4 votes
2 answers

Are magnetic field lines Spiral for Spiral Galaxies? If no, then how it look like topologically?

I am an undergraduate doing summer project at USO. I am working on Sun's Magnetic field model. I got spiral graph for that, which looks like any spiral Galaxy. Do you think that there is some ...
Kartik Chhajed's user avatar
2 votes
1 answer

Relationship between galactic rotation and stellar lifetime

I have read that the lifetime of stars is much less than the period of rotation for a spiral galaxy. For example ...
Vladislav Eigelbertman's user avatar
4 votes
1 answer

How is the bar formed in a Barred-Spiral galaxy?

How does the bar in a barred spiral galaxy form? What prevents it from being spirals all the way down like water spiralling down a plughole?
Beta Decay's user avatar
0 votes
1 answer

What are evidences of stationarity of rotation of galaxies

Recently I have found the article Does There Really Exist the Problem of the Dark Matter in Spiral Galaxies? which states that dark matter does not exist because astronomers are wrong assuming ...
Truffaldino's user avatar
2 votes
1 answer

In which direction does the Milky Way rotate?

We don't have a photo of our Milky Way the whole, all the pictures are artists' interpretations showing a bulge, a central bar, and several spiral arms. The milky way is spinning. I would like to know:...
Mishu 米殊's user avatar
3 votes
1 answer

Have parameters been determined for the Fourier components of a Milky Way spiral density-potential model?

Spiral arms in galaxies can be modeled by potentials of the form $$\Phi_{\text{spiral}}(R,\theta,z,t)=\sum_mA_m(R,z)\cos(m\theta-m\theta_0-\phi_m(R)-\Omega_pt)$$ where $A_m(R,z)$ is the $m$th-order ...
HDE 226868's user avatar
  • 36k
11 votes
1 answer

Do we know if we are overtaking or falling behind our arm?

Here's our galaxy as best we know, courtesy of this Wikipedia article: It seems that as best we know, each arm is a compressed or brighter area (rather like a wave). Looking at that image, do we ...
Fattie's user avatar
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