Milky Way's heart revealed
 

This is what our galaxy is believed to now look like. There are billions of galaxies in the Universe.

[img]http://www.newscientist.com/data/images/ns/cms/dn7854/dn7854-1_600.jpg[/img]

[quote:8e49b]Bar at Milky Way's heart revealed
18:03 16 August 2005
NewScientist.com news service

The Milky Way is not a perfect spiral galaxy but instead sports a long bar through its centre, according to new infrared observations from NASA's Spitzer Space Telescope.

Galaxies come in a wide variety of shapes usually thought to be produced by gravitational interactions with nearby objects. Some spiral galaxies look like pinwheels, with their arms curving out from a central bulge, while others have a straight bar at their centres.

Radio telescopes detected gas that hinted at a bar at the heart of the Milky Way in the late 1980s. A decade later, observations with the near infrared survey 2MASS bolstered the case for a bar, but dust in the centre of the galaxy obscured the observations.

Now, astronomers have used Spitzer to peer through that dust at slightly longer wavelengths, observing 30 million stars in the galactic plane in the region around the centre of the galaxy.

They found that the central bar was much longer than previous observations had suggested - reaching about half the distance between the galaxy's centre and our Sun. The bar is estimated to stretch a total of about 27,000 light years from end to end.

"It is a major component of our galaxy and has basically remained hidden until now," says team member Ed Churchwell, an astronomer at the University of Wisconsin in Madison, US. "The fact that it's large means it's going to have a major effect on the dynamics of the inner part of our galaxy."

Bar food

Stars in the spiral arms circle the galaxy in roughly circular orbits. But the old, red stars in the bar appear to be on more elliptical paths that take them more directly towards and away from the galaxy's core, where a colossal black hole is thought to lurk.

"This bar probably does carry matter into the centre of the galaxy and feeds the black hole," Churchwell told New Scientist.

But it is still not clear what the discovery reveals about the Milky Way's past. "I don't think anybody really fully understands how bars are formed," says Churchwell. "What we do know is that it appears there are so many barred galaxies they must be rather stable. Astronomers have to come up with some kind of model that can explain the stability of these structures."

The team will publish its results in an upcoming issue of Astrophysical Journal Letters and has requested more time on Spitzer to study the innermost part of the Milky Way.
[/quote:8e49b]
http://www.newscientist.com/article.ns?id=dn7854

[quote:8e49b]
Milky Way’s Central Structure Seen with Fresh Clarity
By Robert Roy Britt
Senior Science Writer
posted: 16 August, 2005
10:00 am ET


A new infrared survey that claims to be the most comprehensive structural analysis of our galaxy confirms previous evidence for a central bar of stars.

The bar is embedded in the center of the galaxy's spiral arms and cuts across the heart of it all where a supermassive black hole resides. The survey found that the bar is longer than thought and sits at a sharp angle to the galaxy's main plane.

"This is the best evidence ever for this long central bar in our galaxy," said Ed Churchwell, a University of Wisconsin-Madison professor of astronomy.

The challenge

If you've ever been fortunate enough to see the Milky Way in the night sky, then you can appreciate the frustration astronomers face trying to probe the galaxy's center.

The milky swath of stars visible under a dark, rural, summertime sky represents a fraction of the millions upon millions of stars that crowd the center of the galaxy. We sit on the outskirts, looking in. Seeing through the glow to determine the galaxy's structure is hard.

Even more challenging is peering through all the dust between here there.

The survey was done with NASA's Spitzer Space Telescope, which records infrared light. All objects that emit any heat can be seen in infrared, and this wavelength penetrates dust, so the new survey revealed light from tens of millions of stars hidden to optical telescopes.

Bigger than expected

The bar is made of relatively old and red stars, the survey shows. It is about 27,000 light-years long, or roughly 7,000 light-years longer than previously thought. Churchwell's team also found that the bar is oriented at about a 45-degree angle relative to the main plane of the galaxy, in which the Sun and the other spiral-arm stars orbit.

A light-year is the distance light travels in a year, about 6 trillion miles (10 trillion kilometers).

Other stars exist outside the galaxy's main plane. The Milky Way, like many galaxies, is surrounded by a sparsely populated spherical halo of stars. The main galactic disk is about 100,000 light-years wide, and the Sun sits about 26,000 light-years from the center.

Bars are fairly common in large spiral galaxies, but some do not have them. Astronomers had glimpsed ours and were not sure if it was in fact a bar or perhaps an ellipse.

The results will be published in the Astrophysical Journal Letters.
[/quote:8e49b]
http://www.space.com/scienceastronomy/0 ... y_way.html

theres gotta be some other life than humans in the milky way, seriously.

that is really cool

[quote="Cool Fool":c6dce]theres gotta be some other life than humans in the milky way, seriously.[/quote:c6dce]


imwithstupid: kinda funny that some ppl think that nasa is a waste of money...

That’s awesome, however it would seem like conventional wisdom to assume the center of a spiral galaxy would be a bar, sort of like a blade at the bottom of a blender. Then again I’m probably wrong, still interesting none the less.

I dont understand in I think the 2nd paragraph it says if you have ever been fortunate to see the milky way.....sorry im not good at space etc, but very interested by it but arent we in the milky way, so how do we "see it" other than the starts around us?

If you look in the night sky to teh south east I believe, you will see a band of stars go across the sky. This is other stars in our galaxy as you look at it head on, as if looking at the edge of a piece of paper. It was named "Milky Way" because it looked like spilled milk across the sky. We are on the outside of the milky way, looking in pretty much. We can see these other stars. The milky way is 100,000 light years across. We're probably 20,000 from the edge, so we're looking through 80,000 light years of space.

If you can find Orion the Hunter, you can pinpoint the center of the galaxy. On his belt where his sword comes down, there is a faint cluster of stars that points directly to the center of our galaxy.

Ah alright, but since we are kinda a sprial like a blender cause of that blade. Do we eventually get sucked into the center?

So when we will we start making those trade lanes?

[img]http://www.microsoft.com/games/freelancer/images/screenshots/fl_ss_ss_010.jpg[/img]

[img]http://img.photobucket.com/albums/v645/angry4pe/its-a-trap1.jpg[/img]

The bar really has nothing to do with the fact that the galaxy rotates. All galaxies rotate around a center point if it's a spiral galaxy, elliptical galaxy or irregular galaxy. If they didn't, they'd all fly apart and they wouldn't exist. Part of the reason for the rotation is gravity, the other part I would say is dark matter, but that's a discussion for another time.

In short, no, we will not get sucked into the center. Each arm of the spiral makes one rotation every 250 million years, I beleieve.

Differential rotation is the name given to something that rotates, where the arms keep winding up. Like the blender idea. However, after a short time, say a billion years or so, the galaxy would become extremly wound up. Evidence shows that this does not happen, so differential rotation doesn't happen within galaxies.

I'm not sure if they are exactly sure how spiral arms form, but here is a good webpage to look over:

http://www.astronomynotes.com/ismnotes/s8.htm

You also have to remember that stars die out. Granted, some stars live for a vary long time. Our sun is about 6 billion years old, which means it's made 24 trips around the galactic center. There are stars that last longer than our own, and stars that burn their fuel up in a relativley short period of time. Ours is pretty much right in the middle. It will last about 12 or 13 billion years.

One could argue that the spiral arms don't wind up because many of the stars die out in their natural process.

WAY too much writing and thought to process at 9:37 am and for this board. So I will bow out

what if there are humans in the galaxy, but not on Earth! oOo: oOo:

Very interesting.

WTF....The worlds not flat and earth isn't at the center of the universe? wallbash:

Kidding all aside, interesting article & cool pic