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Questions tagged [milky-way]

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2
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1answer
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Milky Way Density

It seems to be a simple question, but I wasn't really able to find an appropriate answer: How dense is the Milky Way? I am certain that there are reliable statistic, maybe even new ones from the GAIA ...
4
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1answer
53 views

What's the eccentricity of our sun's orbit around the center of the galaxy? [duplicate]

Just thinking about "galactic habitability zones." Is this even a valid question?
2
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2answers
119 views

Dark matter density calculation

I find that the general dark matter density of the Milky Way is $$6.87 \times 10^9 \: \rm GeV/m^3$$ or $$1.225 \times 10^{-17} \: \rm kg/m^3$$ (by taking the size of the Milky Way and dividing it to ...
2
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1answer
64 views

What does the gravitational potential of the Milky Way do to the CMB?

We sit in a gravitational potential, so there should be a blue shift on the CMB light from the potential of the Milky Way. Is this blue shift dependent on direction? Is it being subtracted from the ...
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0answers
22 views

Is it possible to see the Milky Way galaxy through a gravitational lens? [duplicate]

I have been thinking about these amazing images of ancient galaxies we can see because of gravitational lensing. Some of them even have multiple images of the same galaxy in two different places ...
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2answers
473 views

Does the Sun revolve around the supermassive black hole at the center of the Milky Way? [duplicate]

I'm curious to know, does the sun really revolve around the black hole at the center of the galaxy?
1
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2answers
85 views

Path to a distant star

Suppose we have a space ship that can go fast enough (0.9c) and we have plenty of time, and we want to travel to a star on the other side of the galaxy. How do you plot a path to navigate to that star?...
38
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6answers
7k views

What is the evidence for a supermassive black hole at the center of Milky Way?

Black holes cannot be seen because they do not emit visible light or any electromagnetic radiation. Then how do astronomers infer their existence? I think it's now almost established in the scientific ...
0
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1answer
45 views

Estimating total mass inside the Sun's orbit

I'm trying to estimate the local density of dark matter at a given radius, $r=R_0=8\text{kpc}$. I also have values for the core radius, $a=5\text{kpc}$, and circular velocity of the Sun, $v_{\text{...
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0answers
25 views

Estimating the reddening of a star? [closed]

I'm stuck on a question concerning how to estimate the reddening of a star. The question is: "A star near the Galactic plane has observed apparent magnitudes in the blue and visual bands of $B = 15....
0
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1answer
54 views

Milky way without black holes in the center [closed]

I understand that the Milky way is a spiral galaxy with a supermassive black hole in the center. I understand that because of the stress-energy and the gravitational field of the black hole, the ...
4
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2answers
177 views

The Sun's Orbit - Is it What We Think?

I was thinking that the sun must orbit something within our spiral arm in the Milky Way, or be affected by other astronomical bodies - surely not just the supermassive black hole centre. I have ...
0
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0answers
24 views

Estimating the age of the Fermi Bubbles

Assuming the Milky Way’s Fermi Bubbles were caused by a single event near the galactic center, what are the limits to when that event could have happened? The bubbles reach 25,000 light years high, ...
2
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1answer
251 views

What is the current shape of the Milky Way?

Things in the Universe which are thousands of light years away from Earth can be seen, or pictures can be taken by Hubble Telescope, because those stars, galaxies, etc. emitted light thousands, ...
1
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1answer
73 views

Is there a Neutron Star or Black Hole close to solar system?

I recently read an article where it mentioned that the solar system could be born out of a supernova explosion (death of a previous star). In case there was a supernova, wouldn't there be a ...
1
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1answer
83 views

What is the local stellar number density?

Is it just me or does this paper, while providing a great equation for the behaviour of the general stellar number density, never actually give a value for the local stellar number density $\rho(R={\...
12
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1answer
2k views

If our galaxy's dark matter halo is so large and diffuse, why is the ordinary matter in it so much more localised and compactly located?

I just read that our galaxy's dark matter halo is estimated to be 1.5m ly across, compared to the visible galaxy's 100k ly across, needed to explain stellar rotation curves. Why would this be? By ...
0
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2answers
78 views

If the Universe is expanding, then why will Andromeda collide with the Milky Way? [duplicate]

Andromeda is moving towards the Milky Way Galaxy at around 250,000 mph, but I wonder what is the direction of our Milky Way Galaxy? Are these two galaxies heading towards each other or Andromeda will ...
-1
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1answer
53 views

Frame Dragging by Sag A star

Is frame dragging by the supermassive black hole Sag A responsible for the milky way's rotation? If so would we also be part of time dilation depending on how close we are to Sag A? Is the gravity ...
1
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1answer
56 views

During which part of the year does the Earth move toward the galactic centre?

The Earth orbits around the Sun which in turn orbits around the center of the Milky Way. In which part of the year is the Earth is moving away from the center of the Milky Way?
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2answers
80 views

Spin of Supermasive Blackhole

How long does it take for the black hole at the center of our galaxy to make 1 full rotation?
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4answers
135 views

Can a super-duper massive black hole eventually eat an entire galaxy?

Might there be some roaming black galaxies out there eating up other galaxies?
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2answers
213 views

How do we know the stars orbiting Sgr A* are orbiting a supermassive black hole and not just the center of mass of the Milky Way galaxy?

It is my understanding the best evidence we have for Sgr A* being the black hole at the center of our galaxy is the incredible velocities of the stars orbiting around it. But wouldn't the stars ...
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2answers
79 views

From a planet in one of our satellite dwarf galaxies, would one be able to see the Milky Way?

Say there was a lifeform not unlike ours native to a planet somewhere in one of our nearest satellite galaxies, say Sagittarius, during their nighttime would they be able to see the Milky Way brightly?...
2
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1answer
171 views

On the trajectory of the Andromeda-Milky Way collision

The Andromeda-Milky Way collision is going to happen in approximately 4 billion years. What trajectory would the Andromeda galaxy follow on its path to collision with the Milky Way? How could this be ...
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1answer
118 views

Frequency of black holes [closed]

How many black holes are considered to exist in the Milky Way.. and is there evidence of a single supermassive black hole at its center?
3
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2answers
121 views

Are we closer to an accurate 3 D image of our galaxy using the Gaia billion star data set?

From the BBC: Report on Gaia Mission Data 14th September 2016 Astronomers working on the Gaia space telescope have released a first tranche of data recording the position and brightness of over a ...
1
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2answers
131 views

Plausibility of black hole in center of galaxy (apparent paradox?) [duplicate]

Reading a question on the Worldbuilding SE site a minute ago about a trip to the other side of the galaxy flying by the supermassive black hole in the center of our galaxy, my immediate first thought ...
1
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1answer
121 views

What is the meaning of a negative Galactic longitude?

What is the meaning of negative longitude in Galactic coordinate system, for instance in this article? Does the longitude $-65^\circ$ equal $295^\circ$?
0
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1answer
46 views

Andromeda Collision vs Intergalactic Expansion

If the expansion of the universe is continuing unabated, which means intergalactic (perhaps even interstellar) space is continuingly expanding, then: Why is the Andromeda galaxy on a collision course ...
1
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2answers
148 views

How has the world remained in balance?

In the center of our galaxy, there is a Supermassive black hole. We were told in early astronomy units of school that black holes are giant vacuums that will absorb/consume the area around it. My ...
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3answers
2k views

What part of the Milky Way do we see?

I have seen several pictures depicting our galaxy, but I would like to clarify the following: Picture 1: Picture 2: What part of the galaxy is depicted in the first picture, which is taken from ...
0
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2answers
285 views

Gravitational Lensing by Sagittarius A in the center of the Milky Way

It was suggested that there is a black hole in the center of the Milky Way, called Sagittarius A. The whole region is heavily obscured by dust, although some very long wavelengths can break through. ...
0
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1answer
695 views

What is the baryonic mass distribution of the Milky Way

There are many, many studies of the Dark Matter halo around the Milky Way but I'm having trouble finding good raw data about visible matter. I'm investigating a MOND like model and would like some ...
5
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1answer
154 views

History of the Milky Way-Quasar

Was our Milky Way a Quasar many years ago? I heard that it is difficult to fuel quasars for many billions of years, after a quasar finishes accreting the surrounding gas and dust, it becomes an ...
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3answers
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5answers
35k views

How do we know what the Milky Way looks like?

There is no way (with the current technology) that we could send a probe outside the Milky Way in a reasonable amount of time. So, how do we know what the Milky Way looks like, and what factors do ...
3
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1answer
112 views

What is this big, white, dense, circular collection of stars in this picture taken from a Telescope? (See the image)

I was visiting this website- http://crest.iiap.res.in/iaonightcam.html, where there was a picture of the night sky coming live from a Telescope. My question is, why is there so many stars in this ...
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2answers
2k views

Do we know what event caused the Sun and Solar System to form?

Some stellar formation theories suggest that stars are formed by shock waves from trigger events such as supernovae. This excerpt from Star Formation basically gives the background to my question: ...
3
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3answers
364 views

Milky Way galaxy central black hole and time contraction of life story

We know that life is almost 4 billion years old on Earth. We also know that time contracts as we approach the event horizon of the massive black hole at the center of the Milky Way galaxy. Now the ...
0
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2answers
313 views

What will happen to the Earth when Milky Way and Andromeda merge?

Hypothetically, if our solar system survived into the far future and human was still around, is the merge between 2 galaxies were a disaster for lives on Earth? Were the Sun get thrown away from the ...
2
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1answer
370 views

Is there a map which shows all the black holes in our galaxy?

I am looking for a map which shows all black holes in the Milky Way. See this exoplanet map for what I mean. http://www.hpcf.upr.edu/~abel/phl/phl_exoplanets_stellar_map.png If it is not existing (...
0
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2answers
208 views

Stellar outflows in the Milky Way

There appears to be a lot of evidence that gas flows outward in Galaxies. I've been trying to parse through the available data and am unable to get a clear answer to this question: is there any ...
0
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1answer
683 views

What is the direction of our solar system in the Milky way galaxy and in the universe?

What is the direction of our solar system in the Milky way galaxy and in the whole universe? Are we heading toward another constellation, not including Andromeda?
-1
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1answer
201 views

What are the coordinates of the center of rotation of our galaxy, relative to ourselves?

So standing outside in the garden, can we physically point to the center of rotation of the galaxy? I understand that from our viewpoint on Earth, it would be a moving point, so allowing for Earth ...
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2answers
1k views

What is a reasonably accurate but simple model of the Milky Way's gravitational field?

I am putting together a toy program which shows how stars move around in the galaxy. To run the simulation I need to know strength of the Milky Way's gravitational field at any location in it. I'm ...
6
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3answers
2k views

What does this stellar mass distribution mean?

According to this pie above and for the "Red Dwarfs" part, which of these is correct : 1) 41% of the stellar mass of a galaxy is in stars with masses < $0.25$ $M_{\odot}$ or 2) 41% of the total ...
4
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1answer
2k views

What is the distribution of Population I and II stars in the Milky Way galaxy?

I have been trying to find out the distribution of Population I and II stars in the Milky Way. The distribution I mean is the percentage of each population to the total stars in the galaxy. So in ...
6
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2answers
3k views

How much of a galaxy's mass is in stars?

I have been trying to find an answer for this question for a while without a success, so I guess it might not have a specific answer. But to make things easier, let's take the Milky Way galaxy as an ...
7
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2answers
8k views

What is the luminosity of the Milky Way galaxy?

The luminosity of the Milky Way galaxy according to this is $5\times10^{36}$ Watts, but this number suggests that there are about 10 billion stars with Solar luminosities in the Milky Way, which doesn'...