How To Grow A Giant Star


A star is born in a frigidly cold, dense pocket, embedded within a giant, dark, interstellar molecular cloud, that ultimately collapses under its own gravitational weight to give birth to the baby star. In the hidden depths of these vast, cold clouds composed of dust and gas, wispy ribbons of material slowly come together and clump and grow for hundreds of thousands of years. Then, squeezed together relentlessly by the merciless crush of gravity, hydrogen atoms within the dense pocket suddenly fuse, setting off a brilliant blazing fire that will last for as long as the new star lives–for that is how a star is born! However, giant stars that are at least ten times the mass of our Sun should not exist–but they do, and astronomers have struggled for years to understand why this is so. In March 2013, a team of astronomers announced that baby stars may grow to enormous masses if they happen to be cradled within a nurturing circle of warmly glowing older stars.

Nuclear fusion is the process that ignites and fuels baby stars, or protostars. A newborn star is constantly balancing two warring forces as it grows. Gravity pulls in gas from the surroundings to nourish the hungry, young star, while the radiation pressure that is derived from nuclear fusion resists the inward pull of gravityand pushes everything out and away from the star. This delicate balance between gravity and pressure lasts for as long as the star “lives” on the hydrogen-burning main-sequence. When an aging star finally runs out of hydrogen fuel, its core collapses, and it “dies”. Small stars, like our Sun, die with relative peace and great beauty, puffing off their outer layers of varicolored gases into Space. The relic core of a small star like our Sun becomes a dense little stellar corpse called a white dwarf. More massive stars die much more violently, in the raging brilliance of supernovae blasts. Neutron stars are the relic cores of massive stars that have gone supernova. However, the most massive stars of all blow themselves out of existence altogether to leave behind a gravitational monstrosity termed a stellar mass black hole.

The larger a baby star grows, the more powerful its radiation pressure becomes. At long last the giant protostar reaches a point where the surrounding, nourishing gas should be blown out into Space because of the strength of this pressure. Stars that are more than 10 times the mass of our Sun should not exist for this reason. Yet, this theory was contradicted by direct observations of just such massive, gigantic stars, which are rare, but do exist. Indeed, hefty stars weighing in at 20 times the mass of our own Star have been observed floating around in Space!

A Circle Of Nurturing Older Stars

In March 2013, a team of astronomers led by two researchers at the University of Toronto in Canada, announced they may have found an answer to the riddle of how giant baby stars are born. The team suggests that giant baby stars come into being if they happen to be born within a circle of fortuitously arranged, nurturing older stars. This circle of older stars must be grouped in just the right way to feed nourishing gas to the hungry newborn protostar–otherwise the giant baby star will just push its food away! The older stars, which are members of previous stellar generations, push the gas right back to the hungry baby star, so that it can feed on it and grow to a gigantic size, and not starve itself out of existence once it reaches about 8 solar-masses. 바카라사이트

The team of astronomers spotted evidence of this sort of convergent constructive feedback with the Herschel Space Telescope, launched by the European Space Agency in 2009. Herschel collected images of an enormous molecular cloud of gas and dust floating around in our Milky Way Galaxy dubbed Westerhout 3 (W3), which is situated approximately 6,500 light-years from our planet. Herschel observed this actively star-forming cloud in the infrared to the microwave parts of the electromagnetic spectrum. The team’s results are published in the April 2013 issue of The Astrophysical Journal.

“This observation may lift the veil on the formation of the most massive stars which remains, so far, poorly understood,” commented Dr. Alana Rivera-Ingraham to the press on March 27, 2013. Dr. Rivera-Ingraham, who led the study when she was still a graduate student in the Department of Astronomy and Astrophysics at the University of Toronto in Canada, is now a postdoctoral researcher at the Institut de Recherche en Astrophysique et Planetologie in Toulouse, France.

To study the mysterious birth-process of giant baby stars, the team of astronomers used Herschel’s two cameras that were able to “see” light that is not visible to the human eye. In order to use these cameras to their fullest potential, the team of astronomers, that also included Dr. Peter Martin, created the HOBYS Key Programme, to investigate this mystery. Dr. Martin is a Professor at the Canadian Institute for Theoretical Astrophysics at the University of Toronto. Research on HOBYS at the University of Toronto is partly supported by the Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada.

The team of astronomers discovered that the densest portion of the W3 molecular cloud was encircled by a crowd of massive, older stars, and this environment provided a very lucky situation for growing, hungry, giant baby stars.


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