Questions regarding systems of large numbers of stars held together by gravity.

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0
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2answers
113 views

How do I see more than just points in the sky?

I just bought a new telescope with these specifications: Aperture: 203 mm Focal Length: 1200 mm F/ratio: f/5.9 I usually use a 28 mm eyepiece, giving me about 42.5x magnification, but I also have ...
2
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0answers
21 views

How do people derive ionized gas mass from optical emission lines in a galaxy spectrum?

Suppose you had an optical spectrum of a galaxy, and you unambiguously detected emission lines from cooling ionized gas -- both forbidden lines like [O II] 3727AA and [O III] 4959,5007AA, as well as ...
1
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1answer
28 views

How can ionized emission line flux decrease as a function of increasing metallicity or abundance?

The chemical evolution of galaxies is an important way to learn about their formation and stellar/gaseous constituents. Many galaxies show narrow emission lines at optical wavelengths (3500-9000 ...
10
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1answer
120 views

Does CIBER Experiment from Caltech suggest that there can be lots of stars which are not in any galaxy?

My question is about the implications of the observations recently made by the Cosmic Infrared Background Experiment, or CIBER, from Caltech. I've read at Caltech web site: "The total light ...
5
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1answer
52 views

Stellar systems: what is the difference between virial, dynamical and thermodynamic equilibrium?

I'm currently going through Binney & Tremaine (2008) on my own to learn about stellar dynamics. I also have been perusing additional online resources such as this scholarpedia wiki. Often when ...
3
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5answers
391 views

Could light be dark matter?

Is it possible that light itself is dark matter? I am speaking of photons (e.g. visible light, infrared, ultraviolet, etc...). I realize light is understood to be massless, but it is obvious it at ...
1
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1answer
28 views

How do I modify redshifts to gain corrected line of sight velocities?

I'm currently trying to collect the data to run an N-body simulation for 11 of the galaxies in the Local Group where proper motions are known, however I don't understand how to get the required line ...
1
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2answers
78 views

Is the motion of the Sun around the Galaxy a result of gravitational pull?

Does the orbit of the sun (and other stars within the Milky way) around the galaxy result directly from radial gravitational force toward the objects in the center of the galaxy, or is there ...
7
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3answers
343 views

Statistically, what would the average distance of the closest black hole be?

The closest confirmed black hole is several thousand light years away from earth. Our galaxy has about 100 billion stars. I didn't find any reliable information on the black hole count of ratio versus ...
4
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1answer
118 views

Is there a map of the galaxies?

I see that there are many maps of a single galaxy, the Milky Way, showing the positions of the stars within our galaxy. I could not find a map of Galaxies, however. Is there such a map? In lieu of ...
0
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1answer
33 views

Is there a strict chronological order that determines the shape of galaxies?

Assuming no collision happens, do all elliptical galaxies eventually become spiral? also when a galaxy becomes spiral or barred spiral, can it switch between these shapes or is it set forever?
0
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1answer
131 views

What are the 10 most abundant elements in the universe by number of atomic nuclei?

I've seen websites that show the ratios of the 10 most common elements but they compare them by relative mass. I think it's more interesting to know the relative abundances of atomic nuclei because ...
4
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1answer
93 views

How many stars are in the Sculptor Dwarf Galaxy?

The Sculptor Dwarf Galaxy is a small satellite Galaxy of the Milky Way. There are many such satellites galaxies and I'm trying to compile basic data on them. However, I can't find an estimate for the ...
2
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1answer
163 views

How do we know galaxy GN-z11 is as far away as it is?

The news media recently reported that galaxy GN-z11, formed just 400 million years after the big bang, is much further away than originally thought at perhaps 13.2 billion light years. They say, ...
0
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0answers
20 views

Convergence of galaxies [duplicate]

What would happen to Earth and other planets after about millions of years at the time of convergence of milky way galaxy with andromeda galaxy? (Supposing the planets and the sun are still there and ...
4
votes
3answers
163 views

How does the concept of a universe with no center work?

I understand basically that the universe is homogenous (looks the same from every point) and I was told in my astro class that it's supposed to have no center, but how that works boggles my mind. I ...
8
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1answer
192 views

Has the great Andromeda Galaxy ever collided with any galaxies?

We know that the Andromeda Galaxy is moving towards the Milky Way and vice versa, so there will be a collision. Because of the vast space between them, the stars as they are defined will not ...
1
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1answer
51 views

Procession of the Equinox

I just learned about procession of the equinox, i.e. the Earth's axis tilts one degree every 72 years. And it takes 72 years/degree x 360 degrees = 25,920 There are many theories to this, i.e. ...
1
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2answers
65 views

visualisation of galaxy density

If I had a long stick that was millions of light years long, and with a width of about the Sun, and I then swiped it through the center of the milky way galaxy, what would the probability be of me ...
2
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1answer
41 views

What methods exist to calculate the ellipticity of galaxies

What methods exist to calculate the ellipticity of galaxies and what are their drawbacks? I have asked this question about ellipticity in the SDSS but I want to know about general methods for cases ...
2
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1answer
86 views

Sloan digital sky survey galaxies

I am trying to get some data from the Sloan digital sky survey (SDSS). This task turned out to be challenging for me as someone with only little knowledge about astronomy and maybe someone here can ...
1
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1answer
71 views

What would be the outcome for life in our galaxy if the merger of the Milky Way and Andromeda creates a Quasar?

If predictions are correct, the Milky Way and Andromeda are set to collide in around 4 billion years. If, when this occurs, a Quasar is formed by matter being accreted to the common galactic center ...
1
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1answer
51 views

Why is it strange that outer stars are travelling with the same speed as inner while the total mass is also increasing?

Astronomers say that it's strange that the outer stars of a gallaxy are travelling with the same speed as the inner stars. Therefor they introduced dark matter to solve this strangeness. The theory ...
0
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2answers
49 views

How probably is it that galaxies will extinguish?

In the nebulaes of galaxies are stars born, but the gasses and dust they are made of comes from exploded stars (fe supernovas). So it looks like these processes can go on continuesly. But is that ...
2
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1answer
76 views

What part of the milky way do we see from earth?

When looking up at the night sky, we can sometimes observe a bright band of stars stretching across it. I know this is our galaxy but exactly what are we looking at? Could we look at the centre of ...
4
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2answers
122 views

Why are stars more metallic closer as you move closer to the galactic bulge?

As I see it, most of the stars in the galactic bulge are Population I stars. However, as one moves farther from the galactic bulge, star metallicity decreases. In fact, halo stars are almost entirely ...
1
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1answer
59 views

Why there is no axis measurement when telling distance between objects in space ?

What's in upper part in our galaxy ? If space is 3 dimensional, what lies beneath solar system, or in upper part ? Why it seems from every graphical view of solar system / galaxy, everything is in one ...
1
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1answer
60 views

Obtaining stars vector position in relation to the center of the galaxy at a given date

How can someone obtain such vector, for stars in the Milky Way? Input should be star data (from a catalog, eg: Hipparcos) and Julian Date. Output should be a Vector Position (in pc) in relation to ...
4
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1answer
162 views

Why aren't new stars in Earth's relative proximity constantly discovered?

Okay, bear with me. In layman's terms: The estimates vary, but on a clear night, away from big cities, one can see up to 5000 stars in the sky. All those are in the Milky Way, but they're hardly ...
4
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1answer
184 views

Is there a strong galactic magnetic field?

My main question is: Is there a strong galactic magnetic field, perhaps driven by the supermassive black hole at the center of our galaxy? I am also wondering if this field would be strong enough to ...
7
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2answers
480 views

How do scientists know there are about 300 billion stars in a galaxy and there are about 100 billion galaxies?

Just to think about this is mind boggling. But how do scientist get these numbers? What technology/system/theory do they they use?
3
votes
1answer
89 views

What is the scale of things you can see with gravitational lensing?

I'm trying to understand the examples of gravity lensing (using the general relativity property of large masses to bend light like a lens). Most of the examples I see are of some galaxy (presumably ...
3
votes
1answer
85 views

Does Dark Matter affect the motion of the Solar System?

Would dark matter have a similar effect on the Solar System as it does on the Milky Way? I'd imagine it could help hold together some of the Solar System bodies or at least affect their motion, right? ...
1
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1answer
96 views

How do we know which elements are in a galaxy spectra?

I know that each element has it's own distinct spectra (this is a good site that lists them: Periodic Table) but when looking at a spectra of a galaxy (or even a star) how do we match those elements ...
3
votes
1answer
102 views

Does the Sun orbit the Milky way in a (kind of) flat or inclined orbit or more of a sine wave? [duplicate]

I know it can't be a perfect ellipse or smooth orbit due to all the matter in every direction, and our Sun could be affected by a gravity assist of sorts if it passes close enough to another massive ...
8
votes
3answers
240 views

How do we know that our galaxy is a spiral galaxy?

I know that our galaxy is spiral in shape, but I'm wondering how the scientists found out that our galaxy has a spiral shape. I don't think we can see the entire galaxy from telescopes on Earth, ...
11
votes
1answer
392 views

What do we know about the lifecycle of the Milky Way (or any other spiral galaxy)?

I know that the Milky Way will collide with Andromeda in the distant future but based on what we know so far there is a supermassive black hole in the center of each galaxy and thus the Milky Way will ...
5
votes
2answers
155 views

Fate of the Spiral Arms of the Milky Way and Andromeda

In a few billion years, the Milky Way and Andromeda will collide. Chances are, there won't be many spectacular stellar collisions, and there's a pretty good chance that the Solar system (and most ...
2
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1answer
73 views

What will the mass of the new galaxy be?

When the Milky Way galaxy collides with the Andromeda galaxy, what will the mass and volume of the new galaxy be?
8
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1answer
333 views

How Much Overlap Will the Andromeda Galaxy and the Milky Way Have When They Collide?

Measurements of Andromeda's blue shift let us conclude that the distance between the Andromeda galaxy and the Milky Way is decreasing and in a few billion years they will "collide". The blue shift ...
3
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0answers
31 views

How does one find the extinction coefficient of a particular galaxy?

I am doing photometry on a number of objects in a number of different galaxies. I need the extinction coefficients for these galaxies for various filters passes. Is there some database that displays ...
3
votes
2answers
73 views

Acceleration in Galaxies Collision

In the far future the Milky Way and Andromeda will collide. As far I know direct collision between large dense objects (black holes, stars, planets, etc.) is unlikely due to the relative "low density" ...
11
votes
3answers
235 views

Metallicity of Celestial Objects: Why “Metal = Non-metal”?

Metallicity of objects refers to the amount of chemical elements present in it other than Hydrogen and Helium. Note: The other elements may or may not be actual ...
2
votes
1answer
118 views

Are galaxies moving away from us faster than before?

Are all galaxies moving away from us at constant speed even those that may be moving in our direction as the space is being formed? How does nothingness appear to push matter? A black hole sucks as ...
14
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2answers
2k views

Was the Milky Way ever a quasar?

Is there any evidence that the Milky Way could have been a quasar in it's early history? Is it thought that most galaxies come from quasars?
3
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1answer
76 views

Distribution of Stars in Milky Way and globular cluster analogy

Just a quick (and hopefully simple) question on the distribution of stars in the Milky Way and in globular clusters. I was wondering why it IS NOT possible to describe the distributions of stars in ...
15
votes
6answers
15k views

What will happen to life on Earth when the Andromeda and Milky Way galaxies collide?

It is said that the Andromeda and Milky Way galaxies are coming close to each other with a speed of approximately 400000 km/hour. They will be together in the next 4 billion years. What will happen ...
11
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2answers
571 views

How many galaxies have been discovered?

I know Andromeda is our nearest galaxy. But how many known galaxies have been discovered and what are they?
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1answer
86 views

What is a Seyfert galaxy?

I know Seyfert galaxies are types of active galaxies, but I do not understand what separates them from other types of active galaxies. Are they brighter/not as bright as other types of active ...
5
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1answer
143 views

What if our galaxy didn't have a SMBH?

From my understanding, it is believed that almost every big galaxy and especially spiral galaxies have supermassive black holes (SMBH's) at the center. Also, from what I've read, a SMBH isn't required ...