Questions tagged [galactic-dynamics]
Questions regarding interactions between galaxies or between major parts of a galaxy.
24
questions with no upvoted or accepted answers
6
votes
0
answers
92
views
How many galaxies are currently merging?
On the homepage of the galaxies research group at CfA SAO, it states, "Astronomers discovered that as many as 25% of galaxies are currently merging with others." They do not provide a ...
- 4,439
6
votes
0
answers
43
views
Are metallicities of molecular clouds lower in the outskirts of the galaxy?
(this question was originally posted in an answer by user PSR-1937-21 to another post. I find it an interesting one, but since they don't seem to be active anymore, I'm posting it to see if somebody ...
5
votes
0
answers
82
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
4
votes
0
answers
58
views
What's the angle between the sun's galactic speed and the ecliptic?
I know the sun wobbles up and down the galactic plane around 35myr. I don't mind about that component.
I'd like the know the angle between the linear speed of sun around the Milky Way (just the ...
- 141
4
votes
0
answers
89
views
Why do the Centaurus A radio jets have two "arms" each? (Event Horizon Telescope image)
Fig. 2: Image analysis of the final model: a, Model image corresponding to the image from Fig. 1 with a pixel size of 2 μas. Here, the tentative position of the jet apex is indicated with a circle. ...
- 31.3k
3
votes
0
answers
163
views
How do star orbits, density wave theory and dark matter distribution work together?
I got confused while trying to combine these 3 concepts. Would love to hear some detailed explanation.
Density wave theory states that spiral arms are formed by tilted elliptic orbits. Bertrand's ...
- 31
3
votes
0
answers
218
views
How do two supermassive black holes reach "the last parsec" in merging galaxies?
This answer to Why can't supermassive black holes merge? (or can they?) describes the barrier to merging that two supermassive black holes face when two galaxies are in the process of merging or have "...
- 31.3k
2
votes
0
answers
28
views
dark matter in galaxy cluster in intergalactic space
On the rotation speed of galaxies in a galaxy cluster:
-> Is the dark matter associated with each galaxy in a cluster, sufficient to explain the rotation speed of galaxies in the cluster, or extra ...
- 201
2
votes
0
answers
45
views
Formation scenarios for elliptical galaxies?
I am trying to get an overview of the latest research on different formation scenarios for elliptical galaxies and filter out old scenarios in the literature that are today proved to be not sufficient/...
- 829
2
votes
0
answers
54
views
Galactic rotation speeds - questions from a non-astronomer
Are there any observations that more distant galaxies appear to rotate more slowly than closer galaxies?
What methods are used to measure the rotational speed of galaxies? (both orbital speed ...
- 21
2
votes
0
answers
119
views
Need help on Springel model for galaxy simulation
I am working on a code for galactic dynamics simulation. Initial conditions (positions and velocities) are based on a model with a massive dark halo and a thin exponential disk.
Now, from the ...
user16492
1
vote
0
answers
24
views
At what distance does the galactic tide significantly affect the orbit of a heliocentric object?
The title essentially explains the question. I was wondering if the galactic tide could play a role in raising perihelia of extreme trans-Neptunian objects (i.e. Sedna) versus the effect of a ...
- 6,613
1
vote
0
answers
14
views
How to obtain the SDSS’s five-part imaging ID number for a list of galaxies whose Ra Dec is known?
I am trying to obtain the FITS file of a few hundreds galaxy from SDSS DR12 Survey. SDSS tries to download the FITS File with the link that contains the information about SDSS’s five-part imaging ID ...
- 11
1
vote
0
answers
22
views
Why use this density function to derive the Lane-Emden equation?
I am currently reading Binney and Tremaines Galactic Dynamics, learning about spherical systems. In chapter 4.33 a density function (Eq. 4.83) is given as:
$$ f(\mathcal{E}) = \begin{cases} F \...
- 111
1
vote
0
answers
91
views
Can this ppxf fit work?
I am trying to do kinematical analysis of spectra using ppxf-algorithm from Capellari. The velocity dispersion I get seems to be to high and I am not sure what the reason could be. On the website of ...
- 829
1
vote
0
answers
41
views
Is the Condor Galaxy (NGC 6872) the result of a non-collision galaxy interaction?
All the interacting galaxies that I can find are of collisions, I'm trying to find an example of a fly-by galaxy interaction. Is the Condor Galaxy an example of one?
Wikipedia's NGC 6872; Possible ...
- 1,301
1
vote
0
answers
85
views
Why we can approximate the mass of spiral galaxy like this?
This is a question from Galaxies in the Universe: An Introduction(2nd edition),Linda S.Sparke&John S. Gallagher III. As shown in the picture
My question is why we can neglect the bulge of spiral ...
- 41
1
vote
0
answers
30
views
What new instruments "so sensitive that we can see (large circumgalactic winds) have only been on telescopes for a few years"?
The Rhodes College press release Prof. David Rupke and Team of Astrophysicists Make Major New Discovery About Galaxy Evolution links to
Astronomy Community/Nature.com: The Making of Makani; The story ...
- 31.3k
1
vote
0
answers
97
views
What is the largest cluster of merging galaxies?
Reading about the Andromeda–Milky Way collision, a galactic collision predicted to occur in about 4.5 billion years between the two galaxies, I went to the galaxy merger page and Wikipedia states that ...
- 437
1
vote
0
answers
34
views
Population histograms and relationship between size of galactic disk and amount of dark matter
I am interested in seeing a plot of dark to baryonic matter ratios in terms of the galactic disk size (when it applies, as not all galaxies fit into disk shapes, and probably analyzing disk galaxies ...
- 153
1
vote
0
answers
36
views
Looking for a Dwarf Galaxy < 500 L.y. in Diameter, which is not a Satellite / Companion, or is at least 500 000 L.y. away from another Galaxy
My goal is to learn about an example of a Dwarf Spheroidal or a Dwarf Irregular Galaxy which is not a Satellite / Companion Galaxy (or is at least 500 000 L.y. away from another Galaxy), and doesn't ...
- 19
1
vote
0
answers
129
views
Virial coefficient when computing dynamical mass enclosed by a rotating galactic disk of gas
Suppose I have a large thin disk of rotating gas in a galaxy -- the disk has a maximum inclination-corrected $V_{max}$ and a maximum radial extent of $R_{max}$ corresponding to that $V_{max}$ ...
- 693
0
votes
0
answers
49
views
Galactic rotation curves data samples: how to get them?
I am aiming to introduce data Science to my High-School students and I thought about giving to them data taken from galactic rotation curves (spiral galaxies at the moment) to stude the flatness of ...
- 399
0
votes
0
answers
62
views
What are Stokes parameters for galaxy shapes, how do they compare to Stokes parameters in optics?
I remember Stokes parameters as a way to completely define the polarization state of a well-defined beam of light. However several questions here refer to Stokes parameters used in characterizing the ...
- 31.3k