Star Birth in an Eagle’s “Nest”
● HOW are stars born? Why are some larger and brighter than others? In spectacular fashion a set of photographs taken by the Hubble Space Telescope may reveal star formation in action. This unique activity is occurring in the midst of the Eagle Nebula, a cloud of gas and dust in our Milky Way galaxy.
To stargazers on earth, the Eagle Nebula has the appearance of a bird with outstretched wings and talons bared. Astronomer Jeff Hester and his colleagues at Arizona State University were interested in photographing the area of the talons, which individually form pillarlike columns that resemble elephant trunks. There, ultraviolet radiation has been ionizing hydrogen molecules—that is, stripping away their electrons.
The mosaic of Hubble photographs reveals dozens of small fingers protruding from the ends of the pillars. At the fingertips, condensing gas forms spherical globules in which stars and, according to some astronomers, perhaps even planets may be developing. However, growth of these objects is being arrested by strong stellar winds from about a hundred infant stars that formed from the nebula earlier. The brightest of these stars may be 100,000 times as bright as, and more than eight times as hot as, our sun. Their radiation has already apparently eroded thinner parts of the nebula. This process, called photoevaporation, may stall star formation by removing material that otherwise would be swallowed up by embryonic stars. In the photographs the evaporating gas looks like steam rising from the gas-and-dust columns.
For one of these gaseous globules to begin shining, it must be massive enough to generate nuclear reactions. Scientists estimate that its size has to be at least 8 percent of that of the sun. In addition, enough of the surrounding dust needs to be removed for light to escape. However, if the globule does not become large enough to shine, it may simply become a dark gas ball known as a brown dwarf. Recently, astronomers discovered their first identifiable brown dwarf.
The resemblance of the dust clouds in the Eagle Nebula to immense thunderclouds seen on stormy days may fool you into thinking that the dust clouds are not very large. In actuality, each cloud pillar is so long that a flash of light originating at one end must travel for nearly a year to reach the other end. Also, each “tiny” globule in the image is about the size of our solar system. Moreover, the nebula is so far away that light from it took about 7,000 years to reach us—traveling at a speed of 186,282 miles [299,792 km] per second. This means that we are viewing the Eagle Nebula as it looked before man walked the earth.
Astronomers observe that star formation seems to occur in other nebulas as well, such as the Orion Nebula. However, the viewing angle for these other examples prevents clear observation of the process. Stars may also die by simply burning out, by exploding violently in a supernova, or by collapsing under the force of gravity and becoming a black hole. The Creator of the universe, Jehovah God, keeps an accounting of the stars, for they are all numbered and named by him. (Isaiah 40:26) The stellar eagle’s “nest” may demonstrate some of the ways in which God has been “forming light” and producing stars that differ in glory.—Isaiah 45:7; 1 Corinthians 15:41.—Contributed.
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J. Hester and P. Scowen, (AZ State Univ.), NASA