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Tags: barred, From, galaxy, know, milky, Point, spiral, Vantage
It’s done by using data and information from the ENTIRE range of electromagnetic radiation.
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In 2005, observations by the Spitzer Space Telescope backed up previously collected evidence that suggested the Milky Way is a barred spiral galaxy. Observations by radio telescopes had for years suggested our galaxy to be barred, but Spitzer’s vision in the infrared region of the spectrum has provided a more definite calculation.
Barred spiral galaxies are relatively common, with surveys showing that up to two-thirds of all spiral galaxies contain a bar. The current hypothesis is that the bar structure acts as a type of stellar nursery, fueling star birth at their centers. The bar is thought to act as a mechanism that channels gas inwards from the spiral arms through orbital resonance, in effect funneling the flow to create new stars. This process is also thought to explain why many barred spiral galaxies have active galactic nuclei, such as that seen in the Southern Pinwheel Galaxy.
The creation of the bar is generally thought to be the result of a density wave radiating from the center of the galaxy whose effects reshape the orbits of the inner stars. This effect builds over time to stars orbiting further out, which creates a self-perpetuating bar structure. Another possible cause of bar creation is tidal disruptions between galaxies.
Bars are thought to be a temporary phenomenon in the life of spiral galaxies, the bar structure decaying over time, transforming the galaxy from a barred spiral to a “regular” spiral pattern. Past a certain size the accumulated mass of the bar compromises the stability of the overall bar structure. Barred spiral galaxies with high mass accumulated in their center tend to have short, stubby bars. Since so many spiral galaxies have a bar structure, it is likely that it is a recurring phenomenon in spiral galaxy development.
Recent studies have confirmed the idea that bars are a sign of galaxies reaching full maturity as the “formative years” end. A team led by Kartik Sheth of the Spitzer Science Center at the California Institute of Technology in Pasadena discovered that only 20 percent of the spiral galaxies in the distant past possessed bars, compared with nearly 70 percent of their modern counterparts.
Studying the core of the Milky Way, scientists found out that the Milky Way’s bulge was peanut-shaped. This led to the conclusion that all barred spiral galaxies have a peanut shaped bulge. When observing a distant spiral galaxy with a rotational axis perpendicular to the line of sight, or one that appears “edge-on” to the observer, the shape of the bulge can be easily observed, and therefore quickly classified as either a barred spiral or a regular spiral. Galaxy NGC 4565 has been classified as a unbarred spiral galaxy using this method.
Source: Wikipedia – The Free Encyclopedia….”
http://www.optcorp.com/edu/articleDetailEDU.aspx?aid=1792
http://kids.yahoo.com/science/space/article/milkyway
Personally, I can’t STAND it when ANY one says that new knowledge is IMPRACTICAL. That’s DELIBERATELY AND INTENTIONALLY insulting to ALL scientists.
Using radio waves, astronomers have mapped the galaxy’s spiral arms, and there appears to be a bar structure in the center.
We’re able to use telescopes to see other parts of the galaxy. Based on the light we collect, we can tell how far away those parts are, how bright they are, and in what direction they’re moving. Combining this data for many different regions of the sky allows us to put together a fairly comprehensive map of the galaxy, showing it to be a barred spiral.