Classifiers have debated whether it should be termed a transitional spiral, a stage between a spiral one without a bar and a fully barred spiral. If there is a slight growth of structure in one part of the galaxy, it can have a dominant effect that leads to more instability, creating a situation where stars start wandering off from their smooth, circular orbits and produce a bar-like structure appearing in the overall morphology of the galaxy itself." The scientists promise further studies to improve understanding of the process.Īlthough mankind has lived here since our beginning, only within the past half-century was the Milky Way found to be a barred spiral. "(P)assing interactions with other stars can leave stellar orbits unstable. One theory is that the interior of the galaxy is rotating slightly faster than the outside, they add.
#BARRED SPIRAL GALAXY DRAWING FULL#
One of these massive bars of stars crossing a spiral galaxy's disk is a sign that the galaxy has reached " full maturity," according to Hubble Space Telescope scientists. In barred spirals, the spiral arms of the galaxy appear to spring out of the ends of the bar." "Some spiral galaxies are what we call 'barred spirals' because the central bulge looks elongated - like a bar. The bulge and halo consist mainly of older stars, where spiral arms have more gas, dust and younger stars.
The arms and bulge are surrounded by a faint halo of stars. When spiral galaxies merge, these patterns can be demolished and the material reconstituted as a larger elliptical.Ī NASA primer notes that spiral galaxies "have a distinctive shape with spiral arms in a relatively flat disk and a central 'bulge.' The bulge has a large concentration of stars. At times they stream across vast distances as the galaxies' gravity tugs at one another.
Sometimes the galaxy's arms are stretched out of joint by passing galaxies sometimes they are highly distorted and wound into separate-looking circular patterns. The sweeping arms of a spiral galaxy give a dramatic aspect, like a spinning ice-skater drawing in her arms as she twirls. Astronomers have known for many decades that our Milky Way is a spiral galaxy arms can be seen by the unaided eye. This sort has immense arms of stars, dust and gas that stretch out from the center, the nucleus, curving around in a spiral shape. Editor's note: A version of this was previously published on the author's website.Īstronomers classify galaxies into three general types: elliptical (oval or ball-like), spiral, and irregular (blotchy), of which the spiral is the most common.
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