Milky way Definition and 182 Threads

Homework Statement In the Solar neighborhood, the Milky Way has a flat rotation curve, with V(r)= Vc where Vc is a constant, implying a mass desnity profile ρ(r) ~ r^-2 Assume there is a cutoff radius R beyond where the mass density is zero. Prove that the velocity of escape from the...

My understanding is that if for example one object is orbiting another, then the mass center of the two masses is located somewhere in between the two objects. And if we have many object (for example stars), then the mass center of the total system can be located another place than were any star...

Hi ! Somewhere I read about our solar system is going slowly out of our galaxy (moving backward from the center, but then I can also read our solar system is approaching center with sonic speed. So how is our solar system actually moving toward the centre of milky way (beside rotation around...

This makes me wish we didn't have so much light pollution here. This is a nice timelapse video of the milkyway. http://news.yahoo.com/blogs/technology-blog/jaw-droppingly-gorgeous-video-captures-milky-way-earth-234619211.html

I was recently asked a few questions about these galaxies. As I was by no means sure of my responses (apart from the last :biggrin: ) I am posting the questions and answers in the hope that someone will either confirm or better them. In an expanding Universe, why are Andromeda and the Milky...

Are there any big difference of star distribution and H-atom distribution in the Milky Way on large scale (larger scale than starts)?

Hi, I'm slightly confused about how we see other galaxies in the night sky ... Looking at this image of the milky way and our position Why does the milky way look like a streak across the night sky like this http://en.wikipedia.org/wiki/File:Milkyway_pan1.jpg" If we...

Homework Statement (2) A star orbits the centre of our Galaxy in a plane perpendicular to our line of sight. If the angular speed of this star in the sky is 40 mas (milli-arc-seconds) per year, calculate its velocity. Assume that the distance of the Galactic centre is 8 kpc. (3) If the...

Homework Statement Orbital motions are routinely used by astronomers to calculate masses. A ring of high-velocity gas, orbiting at approximately 3.4 × 104 m/s at a distance of 25 light-years from the centre of the Milky Way, is considered to be evidence for a black hole at the centre. Calculate...

Why is the Milky Way a barred galaxy? http://en.wikipedia.org/wiki/Barred_spiral_galaxy http://upload.wikimedia.org/wikipedia/commons/8/89/236084main_MilkyWay-full-annotated.jpg

Let us assume Ho = 71 1 / s In order for our solar system to stay in orbit around the milky way, the escape velocity must be greater than the recessional. Resc > Rrec (2GM / R)^1/2 > HoR Now let's refer to Kepler's third law to substitute in for the mass. T^2 = 4π^2R^3 / GM M = 4π^2R^3 /...

Hey guys, What method[s] do astronomers use to count the stars in the galaxy to come up with a number ?

... Obviously we can't fly out and look down on it, so what observations are made to deduce the structure of the galaxy?

How it is possible to capture photographs of milky way. I mean just take a case that we can't take photos of Earth while being on it. For it we have to go out of earth.

I live in Oregon on the coast, so not only do clouds get in the way, but so does light pollution (though I am sure light pollution is just about everywhere you go). Anyways, if there are any frequent viewers of the Milky Way through the naked eye out there, do you know of any places in Oregon...

M = Mass of the galaxy = ? r = Distance of sun from galactic centre = 10kpc= 3.09 x 1017 km (3 sf) G = Gravitational constant = 6.67 x 10-11 Nm2kg-2 v = Radial velocity of the sun = 220,000 ms-2 Since the Sun’s orbit around the galactic centre is nearly circular, it undergoes...

I was wondering what is the source of the magnetic field of our galaxy. Is it possible that such source could be the super massive black hole in the center of the galaxy? Regards.

The Milky Way crosses through the constellations Cygnus, Cassiopeia, Perseus and Sagittarius, so what direction does the Milky Way appear to cut across the sky? What is the Milky Way? (Hoping to hear something other than the standard definition) Why does it appear thicker near...

Does the milkyway orbits anything ?? like sun orbiting center black hole of our galaxy Does the milkyway orbits anything ?? like sun orbiting center black hole of our galaxy i have this question bcoz our moon moves towards(orbiting) Earth but can't reach or hit Earth bcoz Earth moves...

If an observer on the Andromeda galaxy looked back at us, how would the Milky Way galaxy look to him? Edge-on, spiral face on, or in between?

What is our best knowledge on the mass and spatial distribution of dark matter in our galaxy? Could you give me a good reference?

I had just finished reading a space oddessey, and I had a dream in which there were about 10 people standing around me, each unique, one was a girl with purple highlights, and then in the middle of us (we were in a circle) was like a miniature milky way galaxy, and each of us described a process...

Homework Statement The Milk Way galaxy rotates about its center with a period of about 200 million yr. The Sun is 2 X 10^20 m from the center of the galaxy. How fast is the Sun moving with respect to the center of the galaxy?

Just read an article on Universe Today at: http://www.universetoday.com/77662/missing-milky-way-dark-matter/ The paper is at http://arxiv.org/PS_cache/arxiv/pdf/1011/1011.1289v1.pdf . It introduces what seems to be rather tight constraints on the dark disc. Any cosmologists care to...

Hundreds of "Rogue" Black Holes May Roam Milky Way http://news.nationalgeographic.com/news/2008/01/080110-black-holes.html Astronomers have long known about rogue black holes? How long? Is this a new revelation about DM and BHs?

What leads us to believe that there is a black hole in the center of the milky way? If there is one, why is the center of galaxies always depicted as being a bright sphere? Is it a rotating black hole, and how would've it formed?

Hi! I am reading text in metal abundances, for example one of my books states that the metallicity of the milky way is: z = 0.02 etc. Is that mass or number fraction? I have searched in all my books and google a bit but can't seem to find an answer :S Help

These are the problems... 1. At 1G of acceleration, how long does it take to reach the speed of light (299 792 458 m / s) relative to the object accelerating? Obviously it never reaches the speed of light relative to the Earth but I'm also curious what this speed is relative to us. 2. This...

http://spaceflightnow.com/news/n0601/09milkyway/ http://spaceflightnow.com/news/n0601/11hubbleorion/

Here is a poll...how many alien civilizations do you think are existing in the Milky Way at this moment. - 1 - 10 - 50 - 100 - 1000 - 10 000 or more I would vote for 50

How many times more luminous is the Milky Way compared to our Sun?

measured from one end to another end, how many kilometerS? if we are also in the milky way, how can we see milky way?