Questions tagged [milky-way]

Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.

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0answers
112 views

How many stars are in the Milky Way galaxy?

So, I've always heard that the Milky Way hosts between 100 billion to 400 billion stars. My problem is very simple: I'm unable to find any research papers on that topic or giving those estimates. I'm ...
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1answer
65 views

If all objects move, where do we go?

Yes I know that the sun and planets in the solar system travel fast with an average speed of 448,000 mph. Are we going to the center of the galaxy? If so, does that mean our galaxy is getting smaller ...
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2answers
120 views

How well have we mapped our local neighborhood of stars?

Do we have a reasonable idea of how well we've mapped our local neighborhood of stars? That is, about what fraction we know about vs. what fraction are unseen (too dim, too much dust, not enough ...
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1answer
608 views

Are there black holes and neutron stars in satellite dwarf galaxies orbiting around Milky Way?

It is thought that the number of satellite dwarf galaxies orbiting around Milky Way is counted in hundreds. Are there black holes and neutron stars in satellite dwarf galaxies orbiting around Milky ...
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2answers
119 views

What is the (overall) half-mass radius of Milky Way

I am doing some simulation and I need the half-mass radius of Milky Way (total mass: including all objects, dark matter, nebula...), but I cannot find the value and I don't know how to calculate it. I ...
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1answer
84 views

How big is the Lorentz force on the Sun?

The LOFAR observations have made an estimate of the magnetic field of the Milky Way. The value in our region is very small. About 1/1000 of the Earth magnetic field. The Earth and the Sun move at a ...
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1answer
933 views

How big is the energy content of the magnetic field of the Milky Way?

Galaxies have associated magnetic fields. So does the Sun and so does the Earth. In the case of the Earth and Sun it seems clear that the energy content of the magnetic fields is much less than their ...
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1answer
99 views

Why is the Milky Way's SMBH inactive?

Our galaxy is not an active galactic nucleus (AGN). With so many stars and so much gas orbiting it, as explained here Central kiloparsec of Seyfert and inactive host galaxies: a comparison of two-...
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1answer
93 views

Why was it so difficult to figure out the form of the Milky Way?

The exact form of the Milky Way was figured out the in early fifties of the 20-th century. Why did it take so long to see? Is it because we are in the "middle" of it? In general, it's easier ...
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1answer
400 views

How big is the galactic magnetic field in the solar system and how can we measure it?

The Milky Way has an associated magnetic field. But how big is it influence in the solar system and can we measure it? I mean, when measuring, how can we make the distinction between the field of the ...
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1answer
529 views

How do astronomers calculate the period about the wave motion of the solar system in the Milky Way?

According to research, excluding the motion of the entire galaxy, astronomers found the motion of the solar system in the Milky Way. The solar system revolve around the galactic bulge of the Milky ...
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132 views

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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38 views

Is it possible to observe Lyman-continuum emission from extragalactic objects?

Lyman-continuum (LyC) emission is everything blueward of 912 Angstroms (so it includes extreme UV photons, X-rays and gamma rays). There are many low-redshift astrophysical plasmas such as the diffuse ...
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1answer
117 views

Does the galaxy look like a Web or a Tree?

Suppose we have a distance cutoff $r_0$. Let's say that any two stars in the galaxy with a relative distance below $r_0$ have a path between them. Would the path-connected Milky Way look like a Web in ...
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1answer
93 views

How galactic density falls using Oort constants

I am given the observations that Oort constants $A$ and $B$ are, respectively: $14.5 \text{km s}^{-1} \text{kpc}^{-1}$ and $-12 \text{km s}^{-1} \text{kpc}^{-1}$. From these, I am supposed to conclude ...
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5answers
218 views

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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1answer
89 views

Where can I find a list of retrograde Milky Way stars?

I read in papers that the Milky Way contains some retrograde stars (retrograde to the Milky Way rotation). Does anybody know where I can find a list of them, possibly including data on their distance ...
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19 views

What is time period of sun revolving around the center of Milky Way? [duplicate]

What is time period of sun revolving around the center of Milky Way?
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2answers
116 views

Does this galaxy resemble the Milky Way, and is it relatable as the "template" for the Milky Way?

Taking a look at this photo of comet 2I/Borisov and a background galaxy (2MASX J10500165-0152029): And compare it to this rendition of the Milky Way: The two galaxies slightly resemble each other. ...
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2answers
755 views

Observing the motion of the solar system and galaxy through space?

This is very perplexing. Conditions: planets are moving around the sun (solar system) solar system is moving as part of the galaxy the galaxy is moving through space on some axis galaxy is part of a ...
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1answer
96 views

Are the bright dots in this image individual stars?

I saw this picture of M51 (Whirlpool galaxy) and noticed many, many bright dots around and in the galaxy. I have freehand-circled a few as examples. Are these individual stars (probably supergiants) ...
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Can the lensing effect of Sagittarius A* be used to image the stars diametrically opposite to the sun?

The sun can magnify an image of a source 100 ly away nearly 100 billion times, if the ring is captured from the nearest focal point (550AU). According to Christian Ready of Launch Pad Astronomy, we ...
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1answer
50 views

How do we estimate the dimensions and mass distribution of a galaxy's dark matter halo, beyond the effective limits of its visible matter?

Current research suggests that the Milky Way's dark matter halo may extend up to about 10 - 15 times the size of the visible galaxy, and is believed to be roughly spherically symmetrical. But I don't ...
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2answers
122 views

How big would the Milky Way be if all the stars were emptied into one sphere?

Neglecting the fact that this ball of gas would just collapse on itself - I'm curious if there's an agreed-upon measurement that takes into account the volume of all the ~100 billion stars to predict ...
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1answer
157 views

Looking for a routine to correct for Local Standard of Rest (LSR)

I've been scanning the Milky Way with a Small Single Dish Radio Telescope, obtaining Spectral data with a Span of ~ 2 MHz, centered at the 21 cm line. With this information I can derive a relative ...
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1answer
144 views

Do we know what's "behind the Milky Way"?

If we do, how? And what are those objects on the other side of the galactic center? We can't see through the dense band of light and dust, but maybe in other spectrums the band is much less dense? But ...
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2answers
140 views

What is the mean separation between a star and its closest neighbor in the Milky Way halo?

My question is inspired by this previous question, Are there any stars that orbit perpendicular to the Milky Way's galactic plane?. In the great answer posted by @ConnorGarcia, one commenter said he ...
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2answers
4k views

Are there any stars that orbit perpendicular to the Milky Way's galactic plane?

Most stars orbit in the Milky Way's galactic disc. But is it possible for one to orbit perpendicular to it? Here on Earth since we're inside the galactic plane we can't get a good view of what the ...
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1answer
219 views

Is there a retrograde star that passes closer to the galactic center than our Sun?

Our Sun is moving in a prograde orbit around the galactic center with a distance of about 8 kpc. This paper says there are many retrograde stars in the galactic halo 10-20 kpc from the galactic ...
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1answer
2k views

Do the axes of rotation of most stars in the Milky Way align reasonably closely with the axis of galactic rotation?

The axis of rotation of the Solar System makes a large angle of about 60 degrees relative to the axis of rotation of the Milky Way. That seems unusual - for example, most of the bodies within the ...
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1answer
232 views

What is the closest galaxy?

I think that the galaxy closest to the Earth, that is, to the Milky Way, is the nebula called Andromeda, which is 2.5 million light years away. Despite this great distance, M31 is visible, and very ...
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1answer
430 views

Forms of stellar orbits around the galactic center

Do all stars in orbit around Sagittarius A have approximately circular orbits or are there stars that orbit the Milky Way center very elliptically, like being in the Milky Way's outer rim at apoapsis ...
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1answer
244 views

Why doesn't the black hole in the center of the Milky Way glow similarly to the famous M87 image?

The M87 image made some astronomers famous recently as the first image of a black hole. In the Milky Way, it has been concluded that there must be a black hole due to the movement of stars near the ...
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1answer
131 views

How many supernovae events are on their way from within the Milky Way?

The Milky Way has a diameter of around 100.000 light years with the Solar system placed some 25,000 light years from the center. If we assume a supernova rate of 1 per century, and also assume that ...
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0answers
42 views

Data for "milky way outline" [duplicate]

I am trying to make a software generated star chart, and want to include the outline of the milky way as shown in many such star charts. Does anyone have any idea where to obtain the data for that? ...
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4answers
3k views

Looking for a detailed Milky Way map

I am a UI designer working on a sci-fi strategy video game. I was wondering wether anybody here might be able to help? I am looking for a top down projection of the Milky Way that labels regions of ...
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3answers
555 views

Apparent magnitude of Milky Way?

We have apparent magnitude of stars, planets, DSOs. What about the apparent magnitude of Milky Way? Can it be estimated?
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1answer
90 views

How to approximate the distance at which the thin disk peaks along a given LOS from Earth for a given galactic coordinate per 1 sq deg?

The density of stars drops off exponentially from the center of the galaxy and can be approximated as follows using a cylindrical coordinate system: $$ \rho(R, z) = \rho_0 \exp \frac{-R}{h_R} \ \exp \...
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1answer
330 views

Is there evidence for galactic "seasons"?

The Solar Year has huge effects on our climate, and the signs of passing seasons are physically evident on Earth. I recently learned about the Galactic Year. To my understanding, our sun orbits the ...
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2answers
2k views

Is it true that we see the center of the milky-way for only half of the year?

I'm not an astronomer, please excuse my non-formal language. Since we are located in one of the arms of the Milky way, the center of the galaxy should be in one direction from our location, while in ...
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1answer
928 views

Could the Sun and our Solar System one day leave our galaxy?

I have now learned that the Sun is not fixed in place, so I asked myself this question: It is possible, that the Sun and our Solar System will one day leave our galaxy? If yes, how, and if no, why not?...
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1answer
128 views

Orientation of local star map

This image depicts our solar neighborhood Source The plane defined by the concentric circles, does it have a relationship to any galactic reference points or the ecliptic?
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2answers
527 views

How many times has the Milky Way rotated?

I would think that is a highly naive question, but I still ask it. Given current experimentally discovered numbers: the Milky Way galaxy is ~13-14 billion years old At the galactic radius where our ...
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1answer
132 views

Milky Way as seen by the human eye: where exactly do those photons come from?

I'm asking here about the diffuse glow seen by the human eye, when looking at the Milky Way. Where do those visible photons come from exactly? the surface of a star? starlight bouncing off something ...
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2answers
2k views

Why does the closest approach of star S2 to Sgr A* not appear to be near the focus of its elliptical orbit?

Phys.org's Very Large Telescope sees star dance around supermassive black hole, proves Einstein right links to several ESO videos, including The star S2 makes a close approach to the black hole at the ...
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1answer
146 views

When can I see the Milky Way from the Earth?

Light pollution is restricting most people from ever seeing the Milky Way from the Earth. Is there any place in India where I can see the Milky Way? Is there a database or site with the list of all ...
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1answer
72 views

How does the Sky in Google Earth Pro work?

For those who don't know, Google Earth Pro has a feature where you can see what the sky should look like based on the time and geographical location. I know Google Sky says that Google Earth uses ...
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1answer
236 views

How bright would Sagittarius A* be from Earth if it became an Active Galactic Nucleus?

Essentially I'd like to know how bright our central black hole could appear from earth in relation to full moon brightness. Assuming maximum energy output (like when it's gobbling up an entire ...
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1answer
53 views

Q: star scaling calculation

If in our neighborhood of the Milky Way, the typical spacing between stars is 1 parsec, and the relative velocities between neighboring stars are of order 20 km/sec, what would the spacing between ...
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1answer
235 views

Volume of Galaxies

Pretty much awkward question though. I would like to ask how is the volume of a Galaxy X is measured? For example consider milky way, what are the techniques to measure the same? How accurate and ...

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