Posted on 08/16/2005 7:04:45 PM PDT by LibWhacker
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.
No, an SBa galaxy has a really big central bulge. We are somewhere between an SBb and an SBc though perhaps much closer to an SBb based on the above representation.
This might now be open for debate for some time. It's funny, we know more about other galaxies than our own in many ways. It's like not knowing what you really look or sound like to others... and then you see yourself on video and are actually are surprised that what you're watching at is really you...
I see. Well, what is your personal opinion on whether other civilizations exist in the Milky Way? Yes or no?
I wonder if the chicks there are hot, and if they make a good Jack and Coke.
How did our galaxy get its name? Has it always gone by that name? Who named it?
Personally, I think it's almost inconceivable that we could be alone in such a vast universe! But as I say, the thing that interests me almost as much is, how prevalent is life? Is the galaxy teeming with it? Or will we only find it in one in a million galaxies?
I see you're in California. Me too. The "seeing" is lousy here. Get as far away as you can from city lights and the Milky Way looks like a big milky streak in the sky (because we're viewing it edge on). I think that's where the name comes from.
From Psalms 8:3...
"When I consider Thy heavens, the work of Thy fingers, The moon and the stars, which Thou hast ordained; what is man, that Thou dost take thought of him ?"
SETI does not even aspire to provide any measure of the prevalence of life, but rather of civilizations.
Well, the ancient Greek astronomers named it "Milky" so that's the ultimate origin. Galaktos is the Greek word for milk and that's where the English word galaxy derived from.
PS. If we are to 'find' life in but one in a million galaxies then we've probably already found all the life that humanity is actually ever gonna find.. ;^)
Well the Hubble couldn't see the Grand Canyon or even the Rift Valley of Mars, if the planet was in orbit around one of the Stars of the Alpha Centauri system, a mere 4 light years away. So I don't think that failure means much.
Thanks for the info. Has it been called by different names in different cultures? It would be interesting to know?
Neat picture; do you suppose anyone's looking at it from the other side?
Thanks!
The Milky Way is not a perfect spiral galaxy but instead sports a long bar through its centre
It's a sports bar.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.