Unprecedented view of what stars look like before they are truly stars
dramatic new pictures from NASA's Hubble Space Telescope show newborn stars emerging from massive columns of interstellar gas, giving scientists an unprecedented view of what stars and their surroundings look like before they are truly stars.
The pillars are in some ways akin to buttes in the desert, where basalt and other dense rock have protected a region from erosion, while the surrounding landscape has been worn away over millennia. In this celestial case, it is especially dense clouds of molecular hydrogen gas and dust that have survived longer than their surroundings in the face of a flood of ultraviolet light from hot, massive newborn stars (off the top edge of the picture). This process is called "photoevaporation." The Hubble pictures show photoevaporating gas as ghostly streamers flowing away from the columns. The tallest pillar (shown here) is about a light-year long from base to tip.
As these interstellar columns, 7,000 light- years away in the constellation Serpens, are slowly eroded away by the ultraviolet light, small globules of even denser gas buried within the pillars are uncovered. These globules have been dubbed "EGGs," an acronym for evaporating gaseous globules. Forming inside at least some of the EGGs are embryonic stars.
Some EGGs appear as nothing but tiny bumps on the surface of the columns. Others have have pinched off completely from the larger column from which they emerged, and now look like teardrops in space.
The stars are formed when the density of molecular hydrogen gets so high that gravity takes over and causes the gas to start collapsing into ever-smaller clumps. As more and more gas falls onto these growing clumps they get further compressed by their own weight, until finally they trigger nuclear fusion reactions in their cores, and "turn on" as stars.
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