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Questions tagged [galaxy-center]

Questions regarding the inner portion of a galaxy; in the Milky Way, this is the area around Sagittarius A*.

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Do all galaxies have a black hole in the center?

Would I be correct if I stated that all galaxies have a black hole in the center? Since other galaxies orbit around a center point in a galaxy - the barycenter, right? - I would assume at this point ...
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1answer
276 views

What is the escape velocity of our Galaxy relative to?

I've been thinking that everything has a relative escape velocity, if it has Mass, seemingly. You can escape orbit around the earth by accelerating enough. You can escape the orbit of the sun by ...
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1answer
124 views

Behaviour of black holes

This question could be strictly linked to my another question related to black holes. It’s known that the horizon event is a place where dust,star components are ready to be incorporated to the ...
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1answer
98 views

Extragalactic Magnetic Fields - General Information That I'm Missing

I have started studying Extragalactic Magnetic Fields, and mainly focusing on Biermann Battery Theory. I have gathered much information on other Dynamo Theories, as well as about our current ...
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1answer
99 views

Could a dwarf galaxy host a star at the center instead of a SMBH?

I don't think this would be possible, but I'm curious, and as what ever query I googled I only found posts about black holes indeed existing, what black holes are, that even the Milky Way has a black ...
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2answers
267 views

What is the movement of stars within the nucleus of a barred spiral galaxy

I'm looking for visualizations that show the movement of stars in barred galaxies but not having much luck. I've found many that simulate spiral galaxy arms in general, but none that include a bar or ...
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3answers
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Revolution of the sun

It is believed that there is a black hole at the centre of the Milky Way galaxy. And the sun revolves around the centre of the milky way. So does it mean our sun is revolving around the centre of the ...
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2answers
662 views

Why can I see the Andromeda Galaxy despite Milky Way's rotation?

Okay ... so, I woke up from a dream last night wherein I was (apparently) attempting to devise a time-keeping system for interstellar travel (similar to the stardate system used in Star Trek). In the ...
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2answers
291 views

When we say the sun takes 230M years to orbit the galaxy, what is this in relation to?

When we say the sun takes 230M years to orbit the galaxy, what is this in relation to? We measure the earth's rotation relative to the distant stars. What is the reference for our Sun's motion around ...
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133 views

Does creation of galaxy depend on black holes?

I've read many times that every galaxy contains a black hole at the center. So is the creation of a galaxy linked to black holes?
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1answer
428 views

What's the theoretical maximum density of a galaxy?

In watching this Hubble video on Omega Centari it got me thinking about how dense a galaxy can get. Do we know how dense a galaxy can get? Are there any good resources on reading more about very ...
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1answer
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Accretion discs emitting jets [duplicate]

When there are accretion discs jets of particles or radiations will be emitted in the direction parallel to the rotational axis. My beginner level astronomy textbook just says that it is due to ...
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2answers
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Why is there a supermassive black hole at the center of every galaxy?

According to https://en.wikipedia.org/wiki/Sphere_of_influence_(black_hole) the gravitational sphere of influence of a supermassive black hole is really limited compared to the size of its hosting ...
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1answer
156 views

What may be the period and speed of revolution of the star that is closes to galactic centre?

The Sun moves at the speed of 220km/s around the galactic center in a circular orbit. The sun is located at about 30,000 light years from the galactic center. The Sun orbits around the center of the ...
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1answer
131 views

Question regarding the Milky Way when calculating galactic space velocities for galaxies

I have been calculating galaxy space velocities (where proper motions are known) in order to measure their orbits of the Milky Way using the method proposed in the appendix of http://www.aanda.org/...
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2answers
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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 ...
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1answer
690 views

Best approximation for Sun's trajectory around galactic center?

What is the current best approximation for the path the Sun takes around the center of the Milky Way? I have found some information on the approximate position of the Milky Way's center, the speed of ...
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1answer
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What is in the brightest area of the night sky?

When I look up in the night sky, I assume the brightest area, commonly known as "The Milky Way", is the Galactic Center of our home galaxy. But then I stumbled upon this illustration, which seems to ...
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2answers
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Metal rich or metal poor?

What does the image in the link mean? Are the stars in the halo high in metallicity or low? How about at the bottom by the disk? http://science.psu.edu/alert/images/SDSSmetals.jpg/...
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1answer
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Is metallicity low at the central region or nucleus of the Milky Way?

Is metallicity low at the central region or nucleus of the Milky Way? Does metallicity decrease or increase as we move from the center out to the edges of our galaxy?
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2answers
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Orbiting supermassive black hole or galactic center of mass?

One of the ways they measure the (supposed?) supermassive black hole at the galactic center of the milky way is to measure those tens of stars right at the galactic center that are orbiting what ...
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1answer
792 views

How many light years away is Earth from the closest outer edge of the black hole at the center of the Milky Way?

How many light years is Earth away from the closest outer edge of the supermassive black hole in Sagittarius A* at the center of the Milky Way? I don't mean the distance to the center of the galaxy, ...
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5answers
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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 ...
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1answer
651 views

Supermassive black holes at the center of galaxies

The fact is, many, if not most large galaxies have a supermassive black hole at their center. My question is why? Is it because when these galaxies were first formed supermassive black holes were ...
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0answers
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Torus of the AGN

How much do we know about the structure of the torus surrounding the galactic nuclei? Is the shape defined or still under speculations? And are there different structures for this torus possible i.e., ...
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1answer
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How can we infer the mass of SMBH in galaxies that are not active anymore?

I know it is possible to infer the mass of a supermassive black hole (SMBH) by many methods, i.e., stellar orbits for out Galaxy, Iron line profile from the accretion disk, and probably other methods (...
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Explaining Dark Matter and Dark Energy to layman

With my little knowledge, I know this: Dark Matter The center of a galaxy controls/attracts its objects (stars, planets, comets etc.) towards itself because of gravity. But the mass of the center of ...
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Why don't we see the galaxy center?

When we look at the sky, and see the Milky Way, we mainly see a band, with no real center. On a more accurate picture we can guess the center of the galaxy (see this picture), but we still don't see ...