# 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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### Finding the algular size of galaxy cluster when given the RA and dec cordinates of all the galaxies in the cluster

I have the RA and dec values of all the galaxies in a cluster and i need to find its angular size i do not know how to calculate it
1 vote
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### Have measurements been conducted on the position of the galactic center of mass and the orbit of the presumed black hole at the center?

Related questions have been raised before Is our central black hole actually at the CG of the galaxy? Orbiting supermassive black hole or galactic center of mass? , where explanations have been given ...
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### How to plot object on the map correctly

I am wondering how is it possible to plot the celestial object on the map I have attached if I only know following data: 16h 41m 41,24s 36° 27′ 35,5″
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### Where to find data about as many stars as possible?

I need computer-readable data about as many stars as possible, with their: distance to the Earth (or Sun), their masses, and if possible: coordinates, age, brightness distance to the center (...
1 vote
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### Angular distance calculation in Equatorial and Galactic coordinates

I calculated the angular distance between the Galactic Center and Andromeda in Equatorial and Galactic coordinates and observed that the distance is calculated differently depending on the coordinate ...
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### How can I convert my sky coordinate system (RA, Dec) into galactic coordinate system (l, b)?

I am an astro-particle physics PhD student trying to look for a simulation. I was looking for a conversion formula for sky (or celestial or Equatorial) coordinate system using Right Ascension and ...
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### 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 ...
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### Does the north pole of the Solar System (with respect to the invariable plane) point towards the galactic center?

How is our Solar System as a whole (not the wobbly Earth) tilted with respect to the invariable plane of the Milky Way? I understand our Sun's north pole is largely pointing towards our direction of ...
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### What object(s) are furthest above/below the galactic plane?

This is kind of a spin-off of a question I did about a space telescope surveying the galaxy from above the galactic plane. So, it made me wonder, which object in the Milky Way has been spotted ...
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### How bright would the night sky be in the galactic center?

Given that the star density within a parsec of the center of the Milky Way is about 10 million stars per cubic parsec, how bright would the night sky be if you were on a rocky planet within that ...
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### Is it possible that a star is the center of a galaxy?

I read that the black hole at the center of the galaxy has much less mass than the galaxy itself and that it is somehow held together by dark matter. So now I am wondering if it is possible that there ...
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### Why is the Milky Way called like that? [closed]

From which language is the term milky way is derived and what is the largest star located in it?
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### What do stars in galaxies without supermassive black holes revolve around? [duplicate]

I still don't quite understand what the stars in galaxies without SBHs revolve around. I mean, the stars must orbit something. If the Sun suddenly disappeared, the planets wouldn't just continue in ...
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### If our galaxy is mostly empty space then why does it look so solid?

This question has probably been asked quite a few times, but I'm having trouble finding anything due to the fact that this question is very specific in nature. So I'm asking again. We know that outer ...
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### The activity of the galactic nucleus is cyclic?

Are there observations/theoretical calculations that prove or disprove a cyclic activity of the galactic nucleus (I mean the nucleus is active than stops than become newly active with a time ...
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### SDSS - getting separate u, g, r, i, z frames from SWARP tool and astropy

I am following this paper to extract the u,g,r,i,z image frames from the SDSS image fits files. I have the fits files downloaded (using the bulk data download option from SDSS) and tried to run the ...
1 vote
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### Can expansion of space cause the motion of galaxies, does expansion of space do effect motion of our sun around center and earth around Sun?

I'm just wondering that expansion is anyway related to in effecting motion of a star under the galaxies ? Planets are currently revolving around sun in helix motion, if galaxies has motion as well ...
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### What coordinate system is at rest relative to the center of the galaxy?

I am given equatorial coordinates and I need to transform them into a coordinate system that is at rest relative to the center of the galaxy. The closest thing I could find is galactic coordinates ...
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### How is the Sun tilted to its orbit around the Milky Way's center?

We know how the Sun is tilted in reference to its planets but how is it tilted to Sagittarius A or its orbit around it? Or isn't it tilted at all?
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### What percentage of a spiral galaxy is the center/bulge?

Is there a credible source that can tell me how big the bulge of a spiral galaxy is compared to the rest of the galaxy? Unfortunately, I could not find any.
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### How far have stars been seen beyond the center of the Milky Way?

What lies near the center of the galaxy is of great interest and in recent times the motion of dozen(s) of stars at the center of our galaxy orbiting around Sgr A* have been measured in great detail. ...
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### What is that light of the middle of the milky way galaxy?

I'm Being confused what is that light in the middle of milky way galaxy? Image is from Charting the Milky Way From the Inside Out The text with the image explains a lot about the spiral arms and the ...
1 vote
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### Data on galactocentric distances of various stars?

I'm creating a project for my astronomy class (introductory course) that requires knowledge of the galactocentric distances for many stars. I'm struggling to find a good source on this, and I'd rather ...
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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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### 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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### 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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### 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 ...
1 vote
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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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 ...
1 vote
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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### What came first, the super-massive black holes, or the galaxies surrounding them?

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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### Structure of the torus of the Active Galactic Nucleus

How much do we know about the structure of the torus surrounding the Active Galactic Nucleus (AGN)? Is the shape defined or still under speculations? And are there different structures for this torus ...
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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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