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.
Now, do we have a "good" sample? That's an entirely different question. I think it can be argued either way; we have looked at thousands of nearby stars and so far, nada. So that sample is definitely telling us something.
I don't think we'll ever answer in the negative the question, "Is there life out there?" For that we must look at every star, planet and moon in the universe. But what we can answer (estimate), perhaps very soon or even right now, is how prevalent life is.
The libs who threatened to move to Canada, but didn't now have another option.
Usual estimates run from 100 billion to 200 billion. But I have seen estimates as high as a trillion. Someday we may be surprised to find out how many faint stars are out there that we had no way of estimating back in the year 2005.
Cool picture, We need to explore all of it and plant the American flag on all of it.
Exactly. I think astronomy is fascinating but I tuned into this thread purely for the jokes...
Based on our capability so far, it's like trying to write up a statistical profile of the human species from the ashes of a single 10,000 year old skeleton..
400 billion stars would seem to be the popular answer these days.
So, we live in a bar galaxy... who would have thunk it! Due to it's size and what we know about the "spiral".. I assume it's an SBa type galaxy... or could it be an SBb?
A gigantic bar??? Anybody see Ted Kennedy lately?? Maybe he'll try to get lucky there.
I found what I was looking for under 'aerospace'.
Thank You for your suggestion
Then you'd love Big Bang Bar, the rarest pinball machine out there. About a dozen made, the one at the link eBay'd for over $20,000.
As a pinball fan and owner, I can only drool . . . . .
I recall that the Milky Way is between the b and c categories, so I'd guess an SBc going on SBb. That artist rendering would seem to have the spirals wound up too tight based on what I've read about the Milky Way before and the representations I've seen. Maybe someone more knowledgable could help out!
Yes, all true, but we shouldn't underestimate the power of sampling! For example, there are uncountably, infinitely more real numbers than stars in the Milky Way. Yet you can tell a lot about the real numbers just by looking at a few hundred or few thousand of them between 1 and 100, or between 0 and 1 for that matter. In no way a good sample. But good enough to draw lots of valid inferences.
On second thought, if that rendering is taken to preempt what I've read/seen before, as I guess it probably should, then that would seem to make the Milky Way an SBb.
But you make it sound as if we have a radiographic profile of a thousand stars, or something. We don't. We have a minute, fragmentary, degraded sampling of one narrow wavelength; a wavelength that ironically enough if someone were using it to try to detect life on earth would show them nothing (we aren't transmitting on the wavelength SETI examines).
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