Questions tagged [spiral-arms]
The spiral-arms tag has no usage guidance.
15
questions
4
votes
2
answers
944
views
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 ...
- 355
3
votes
2
answers
264
views
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 ...
5
votes
1
answer
157
views
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 ...
- 701
5
votes
0
answers
86
views
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 ...
- 403
1
vote
2
answers
145
views
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 ...
- 5,636
3
votes
0
answers
66
views
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 ...
20
votes
1
answer
1k
views
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 ...
- 301
47
votes
2
answers
6k
views
Does the sun cross other spiral arms in its movement around the galaxy's center?
Today, Ansa.it 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
...
- 273
4
votes
2
answers
228
views
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 ...
- 266
2
votes
1
answer
49
views
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 https://www.coursera.org/learn/evolvinguniverse/lecture/wlYhz/the-origin-of-spiral-arms ...
4
votes
1
answer
2k
views
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?
- 843
1
vote
1
answer
154
views
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 ...
- 71
2
votes
1
answer
9k
views
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:...
- 201
3
votes
1
answer
148
views
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 ...
- 37.3k
10
votes
1
answer
1k
views
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 ...
- 946