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25 votes
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Is it possible that a star is the center of a galaxy?

It won't stay in the center for long. Galaxy nuclei are full of stars. Any star passing by will exchange momentum with the central star and will perturb its position. Stars of similar mass will be ...
fraxinus's user avatar
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23 votes

Is it possible that a star is the center of a galaxy?

The short answer is, not really. Galaxies are unlikely to have a star at the "center". When you say a star is at the center, what you're really trying to say is that that star is the ...
zephyr's user avatar
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15 votes

Is it possible that a star is the center of a galaxy?

Galaxies are gravitationally bound by the mass of all the stars, gas, dust, planets, black holes and "dark matter" that they are made of. In fact the majority of the mass comes from the &...
James K's user avatar
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12 votes
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Do all galaxies have a black hole in the center?

The answer here is certainly no. Many dwarf galaxies (e.g. the Magellanic Clouds) don't contain supermassive black holes, although some may contain less massive intermediate-mass black holes (Mezcua ...
HDE 226868's user avatar
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11 votes

What is the escape velocity of our Galaxy relative to?

One way to think of the Escape velocity is to imagine it backwards. Instead of a rocket being fired into space, think of the same rocket, starting at rest relative to the Earth at a great distance (...
James K's user avatar
  • 125k
10 votes
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How bright would the night sky be in the galactic center?

Interesting question. Assuming the figure of 10 million stars per cubic parsec is correct, there's still one missing piece of information to try getting a estimate: The size of this region with a very ...
ksousa's user avatar
  • 1,201
9 votes

Revolution of the sun

The Sun orbits in the entire Galactic gravitational potential, which is very approximately similar to that provided by considering that all the mass interior to its Galactic orbit (about 100 billion ...
ProfRob's user avatar
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8 votes
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Could a dwarf galaxy host a star at the center instead of a SMBH?

A galaxy's center of gravity is not determined by the most massive object, but by all objects in the galaxy. Even supermassive black holes (SMBHs) do not dominate the gravitational field except very, ...
pela's user avatar
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7 votes
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When we say the sun takes 230M years to orbit the galaxy, what is this in relation to?

The Sun's velocity is known (with uncertainties) with respect to the Galactic centre (GC), as is the Sun's distance from the Galactic centre. These measurements have a long tortuous history, which I ...
ProfRob's user avatar
  • 155k
7 votes

Why is there a supermassive black hole at the center of every galaxy?

As some of the comments pointed out, there isn't a definite answer since this is still ongoing research. However, there are some things that might explain it: Galaxy formation: Current theory says ...
Alex's user avatar
  • 2,285
7 votes

What is the escape velocity of our Galaxy relative to?

James K's answer is great, I just want to offer a few definitions: Any mass $M$ — whether a be point mass like a planet or an extended mass like a galaxy — has an associated gravitational potential $\...
pela's user avatar
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7 votes
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What percentage of a spiral galaxy is the center/bulge?

The term you're looking for is called the bulge-to-disk (size) ratio. Sort of by definition, the answer depends on the morphology of the galaxy, i.e. how "late-type" spiral it is. "Sa" spirals are the ...
pela's user avatar
  • 38.9k
6 votes

What percentage of a spiral galaxy is the center/bulge?

To answer the title question, what you want to know is the bulge-to-total ($B/T$) ratio, which is the fraction of a spiral galaxy's light (and thus, approximately, its stars) which in the bulge; this ...
Peter Erwin's user avatar
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6 votes
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Why can I see the Andromeda Galaxy despite Milky Way's rotation?

As barrycarter already pointed out, it is due to the huge time it takes for the milky way to rotate. For once, as he pointed out, the stars in an orbit similar like the sun take about 250 million ...
Adwaenyth's user avatar
  • 453
6 votes

Do all galaxies have a black hole in the center?

It's generally assumed that most galaxies have a black hole at their centre. There are galaxies we've detected that don't seem to have a black hole though, so it's not a necessary requirement or a ...
Kyle's user avatar
  • 243
6 votes
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Behaviour of black holes

No, it seems that the formation of a supermassive black hole is a consequence of galaxy formation, not a cause of it. The mass of the black hole is a very small proportion of the mass of the matter ...
James K's user avatar
  • 125k
6 votes
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How can I convert my sky coordinate system (RA, Dec) into galactic coordinate system (l, b)?

Applying spherical trigonometry, it follows that the conversion from equatorial coordinates $\alpha$ and $\delta$ to galactic coordinates $l$ and $b$ is: $$\left. \begin{aligned} \sin b &=\sin \...
Albert's user avatar
  • 2,264
5 votes
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What may be the period and speed of revolution of the star that is closes to galactic centre?

Star S2 reaches maximum velocities of 5,000 km/s according to this ESO page. The orbital period is given as a little over 15 years and this paper gives a peri-center (closest approach to the black ...
Andy's user avatar
  • 2,477
4 votes

Why is the Milky Way called like that?

Milky way obviously is an English word with that literal meaning a way (path) covered in milk. So it's not exactly derived. But it is a literal translation from Latin 'via lactia' and the Greek ...
planetmaker's user avatar
  • 19.9k
4 votes

If our galaxy is mostly empty space then why does it look so solid?

You are mostly empty space. Every atom in your body is very tiny compared to the relatively vast spaces between it and its nearest neighbors. And the same goes for every "solid" object you ...
M. A. Golding's user avatar
4 votes

What is that light of the middle of the milky way galaxy?

The galactic bulge is formed by tightly packed stars and interstellar dust Also most stars are in the direction towards the galactic center Thus it would appear brightest if it were viewed from ...
Danish 's user avatar
  • 381
4 votes

What object(s) are furthest above/below the galactic plane?

Bochanski et al. (2014; "The Most Distant Stars in the Milky Way") reported the discovery of two stars -- ULAS J001535.72+015549.6 and ULAS J074417.48+253233.0 -- found to be M giants at ...
Peter Erwin's user avatar
  • 17.3k
4 votes

How to plot object on the map correctly

No, it's not enough. The coordinates you give are the position in the sky. To plot a location in the galaxy, you'd need also to know the distance from Earth. However, nearly all naked eye visible ...
James K's user avatar
  • 125k
3 votes
Accepted

What coordinate system is at rest relative to the center of the galaxy?

Galactic coordinates are sun centred with a zero longitude chosen to align with the centre of the galaxy when the measurements were made in 1958. As defined, the galactic coordinates don't rotate, and ...
James K's user avatar
  • 125k
3 votes

SDSS - getting separate u, g, r, i, z frames from SWARP tool and astropy

What they did was the following: for each individual filter, they assembled overlapping frames into a combined, single-filter image. E.g., they combined several g-band images into a single g-band ...
Peter Erwin's user avatar
  • 17.3k
3 votes
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Extragalactic Magnetic Fields - General Information That I'm Missing

On this question, the Widrow (2002) review is still pretty up-to-date. You can also have a look on the introduction of Beck (2013), a recent PhD thesis on the subject with a straightfoward ...
MBR's user avatar
  • 5,523
3 votes

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

It is certainly true that the galactic orbit is very slow. Yet it should be noted that even if the Sun/Earth system orbited the galaxy once every century, the Andromeda galaxy would still be seen in ...
Ken G's user avatar
  • 5,336
3 votes

Is it possible that a star is the center of a galaxy?

You've mis-remembered or mis-heard some things and got a bit confused. Let's try to fix that... Supermassive black holes We have discovered that most galaxies have a supermassive black hole at their ...
Stilez's user avatar
  • 1,030
3 votes

How bright would the night sky be in the galactic center?

From Foundations of Astrophysics by Barbara Ryden and Bradley Peterson (which I highly recommend): If the Sun were half a parsec from the Galactic center: . The nearest star would be ∼ 1000 AU away. ....
Vashu's user avatar
  • 212
3 votes

What object(s) are furthest above/below the galactic plane?

Globular clusters orbit in the Galactic halo, and so are good candidates for being far above the disc. The globular cluster PSO J174.0675-10.8774 is the furthest, 470,000 light years distant, well ...
James K's user avatar
  • 125k

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