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.
BTTT
However, your arguments do carry merit. Terrestrial interference is becoming a huge problem. This is why a telescope array with dishes having more than 1000 miles of separation can overcome that issue.
Thanks for the correction RA. It's obvious I learned nothing during the brief period I loaned them my computer back in 1999. Sad to think I was one of their first participants.
You are being too hard on yourself. There are real probs with SETI, I have described a few of them. :-)
While I'm at it I think I'll rejoin the quest!
It's definitely a long shot. I wont kid you there. :-)
The "Flying Spaghetti Monster" knows all; sees all!
"Thou shalt have no main course before Him!"
"In His Noodly Appendage we trust!"
The Flying Spaghetti Monster emits and receives on all wavelegths! All sentient transmission in the Universe are known to Him via his Very Large Noodly Appendage Array. His Harmonic Semolina Oscillations are embedded in every EM signal in the Universe! He is omnipresent!
An entire solar system, most of it not really inhabitable, contains a prodigious amount of resources. The star at it's heart can supply massive amounts of energy too.
Just imagine another tool building species that ends up developing radio and radio astronomy that may also recognizes the importance of this 21cm band. And they also may instigate a SETI search using these same bands such as we do. So here is the question. Would they hear us at those frequencies? They are the very ones that we are not transmitting on at all. I could just see 500 races all looking for each other at the very frequency band that none of them are transmitting on due to the very nature of its importance for the exploration of the universe.
That's part of the reason I think we need to look at additional frequencies to try to detect any "leakage" from their normal communications channels. That is more challenging of course, since they may not be using, probably aren't in fact, nice narrow band waveforms.
But, as you say, if everyone is listening, and no one is transmitting, at least on the "water hole" band, then it's going to be bloody hard to hear find other. :)
Unless the other guys are transmitting spread spectrum, with many "circuits" using the same frequencies but different spreading codes.
Of course there aren't that many good codes. Perhaps we should try some of them and look for a wider band width signal. Maybe we could detect their version of GPS.
Be that as it may, my home PC is right now looking for ET using SETI@Home
That was quite a UFO story on Coast last night. Along with the events and some insight of the UFO infestation of DC in '52 that annoyed Pres Truman, they went into some analysis of Charles Fort's method, interesting.
Sometimes there is no carrier. Single Sideband for example. Of course most of the newer modulation schemes are at base a form of FM or phase modulation, in a sense they are nothing but a carrier, but of course in reality their energy is spread over an even larger bandwidth than the information bandwidth, although hopefully not much wider. That's in part why FM stations are spread farther apart than AM ones. Of course they also have a higher baseband (the music/audio) bandwidth, but their modulation side lobes extend out proportionally farther as well.
At the moment we couldn't see our impressive civilization from Mars. There are some hypothetical characteristics of civilizations that might have achieved a higher level of technology than ours, Dyson spheres, for example, that would alter the spectrum as seen of their central star, that could be seen from a good distance. These are big things that ought to be detectable.
Could be. If we get to the point that we can see those things, there are going to be some other associated developments that just might alter our fundamental relationship with the rest of the universe. Some of these developments could make Star Trek science seem childishly primitive.
We don't even know how the Pyramids were built, or why. Our technology isn't all that impressive so far. We don't even have a decent spacesuit for serious work in space.
A bar at the center of the galaxy is nothing compared to a restaurant at the end of the universe.
What if no advanced civilization has any reason to build a Dyson sphere? My opinion is that we will never build a Dyson sphere and neither will anyone else. However grand the concept, it is nonetheless a crude and costly solution to a problem that IMO almost certainly will not exist by the time we could build one.
It is possible that we have been looking right at such manifestations of advanced civilization all along but have been interpreting what we see as natural happenings. There are some strange objects in outer space that stretch our theory to the max.
Yes, I would agree that this is certainly possible, if not even probable (we won't know until we know). The thing is, I nonetheless doubt that any civilization will ever build a Dyson sphere because there are almost certainly far more efficient and refined ways of getting energy, and that's the conjectured purpose of a Dyson sphere. We may very well be able to pull energy right out of the vacuum before we get to the stage where we could build a Dyson sphere..
Here's a question I've wondered about on occasion: would an array on the dark side of the moon be shielded from terrestrial interference or would the 'ambience' still be so great that it wouldn't make much difference? In other words, if SETI were set up on the moon, could it search the entire spectrum, or at least much more of it?
The Dyson sphere is old tech anyway. The three levels of civilization that Dr Kaku usually mentions on his Coast talks classify civilization by the power they make available for their use. If they are at the level of a Dyson sphere they are just beginning to emerge. We are not yet at the first level, being little advanced beyond wild apes eating berries and leaves.
There are numerous legends in many traditions around the world regarding the creation of the Milky Way. In particular, there are two similar ancient Greek stories, that explain the etymology of the name Galaxias and its association with milk. One legend describes the Milky Way as a smear of milk, created when the baby Herakles suckled from the goddess Hera. When Hera realized that the suckling infant was not her own but the illegitimate son of Zeus and another woman, she pushed it away and the spurting milk became the Milky Way.
Another story tells that the milk came from the goddess Rhea, the wife of Cronus, and the suckling infant was Zeus himself. Cronus swallowed his children to ensure his position as head of the Pantheon and sky god, and so Rhea conceived a plan to save her newborn son Zeus: She wrapped a stone in infant's clothes and gave it to Cronus to swallow. Cronus asked her to nurse the child once more before he swallowed it, and the milk that spurted when she pressed her nipple against the rock eventually became the Milky Way.
Older mythology associates the constellation with a herd of dairy cows/cattle, whose milk gives the blue glow, and where each cow is a star. As such, it is intimately associated with legends concerning the constellation of Gemini, which it is in contact with. Firstly, with Gemini, it may form the origin of the myth of Castor and Polydeuces, concerning cattle raiding. Secondly, again with Gemini, but also with other features of the Zodiac sign of Gemini (i.e. Canis Major, Orion, Auriga, and the deserted area now regarded as Camelopardalis), it may form the origin of the myth of the Cattle of Geryon, one of The Twelve Labours of Herakles.
Peoples in Eastern Asia believed that the hazy band of stars was the "Silvery River" of Heaven. Also, the stars Altair and Vega were said to be two lovers, who were allowed to meet only once a year on the seventh day of the seventh month, when a flock of magpies and crows formed a bridge over the galactic river. That day is celebrated as, (literally the Seventh Night,) called Qi Xi in Chinese, Tanabata in Japanese, and Chilseok in Korean.
Wow! look at that big "accident". And to think, that is just one of them. Must be at least thousands of planets in there where apes are turning into men.
Would be excellent! :-) We would still have the pesky galactic halo noise below about 1GHz though.
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