Researchers may have solved the mystery regarding how some of the most massive stars in the universe form.
These massive stars, which are about 10 times the mass of our own sun, heat up the gas around researchers; researchers have always been stumped as to how this hot gas does not explode outwards, an American Museum of Natural History news release reported.
Recent observations showed that as the gas collapses it forms filamentary structures that are able to absorb the stars' radiation. This causes the nebula to "flicker like a candle."
"Massive stars dominate the lives of their host galaxies through their ionizing radiation and supernova explosions," Mordecai-Mark Mac Low, a curator in the American Museum of Natural History's Department of Astrophysics and an author on the paper, said in the news release. "All the elements heavier than iron were formed in the supernova explosions occurring at the ends of their lives, so without them, life on Earth would be very different."
Stars form when gas clouds collapse; a fusion of hydrogen and helium is what causes the star to shine. This ultraviolet light ionizes gas to form a 10,000 degrees Celsius nebula.
Models have predicted that at this point the gas would rapidly expand but recent observations saw regions of ionized hydrogen instead.
"In the old theoretical model, a high-mass star forms and the HII region lights up and begins to expand. Everything was neat and tidy," lead author Chris De Pree, a professor of astronomy and director of the Bradley Observatory at Agnes Scott College, said in the news release. "But the group of theorists I am working with were running numerical models that showed accretion was continuing during star formation, and that material was continuing to fall in toward the star after the HII region had formed."
The recent observations showed the gas instead formed the filamentary concentrations because there is so much of gravity forced it to "collapse locally." When ultraviolet light passes through these filaments it is absorbed, shielding the surrounding gas.
"These transitions from rarefied to dense gas and back again occur quickly compared to most astronomical events," Dr. Mac Low, a curator in the Museum's Department of Astrophysics, said. "We predicted that measurable changes could occur over times as short as a few decades."
