According to new research, young stars may gain mass by consuming dense clumps of matter that may themselves have gone on to evolve into giant planets. The clumps are believed to be devoured by a star periodically, with intervals of several thousand years between "meals." During periods of brightness following the consumption of one of the cosmic clumps, astronomers estimate that a star could burn up the equivalent of the Earth's mass once every 10 days.
Bodies such as our Sunform in vast swirling clouds of gas and dust that eventually coalesceto form a new star. However, this process does not consume all of thesurrounding matter, the remainder of which forms what is known as anaccretion disk around the freshly-born star.
It had previously beena matter of debate as to how material from this disk was transferredto the infant star, allowing it to grow in mass. The prevailingtheory held that the disk steadily fed matter to the infant star,until the cosmic clouds had been exhausted in the process of swellingthe stellar body, and creating accompanying planetary bodies.
However, this theorywould fail to explain a phenomena observed in young stars, in whichthe stellar bodies suddenly increase in brightness by a factor of 250in only a year. This suggests a massive infusion of new material thatcould not be the case if the star was being fed a steady stream ofmatter.
The new study providesevidence for a separate theory, which, first proposed 10 years ago byEduard Vorobyov of the Vienna University, espouses a moreviolent process for star formation. Vorobyov believed thatgravitational instabilities within the structure of the disk causehighly dense clumps of gaseous material to coalesce, and subsequentlyfall into a young star.
The international teamof researchers made use of the SUBARU 8.2 m (27 ft) opticalinfrared telescope located at the Mauna Kea telescope, Hawaii inorder to isolate arms and arcs in the accretion disks surroundingfour young stars – key features synonymous with thegravitational fracturing model.
"This is a major steptowards our understanding of how stars and planets form and evolve," states Vorobyov, "If we can prove that most stars undergosuch episodes of brightening caused by disk gravitationalinstability, this would mean that our own Sun might have experiencedseveral such episodes, implying that the giant planets of the solarsystem may in fact be lucky survivors of the Sun's tempestuous past."
Source: University of Vienna
