You would probably remember what you studied in school about the process of evolution of stars, but the information you know may be incorrect or at least incomplete,as it is believed by a team of Australian research. Simon Campbell, specialist of stellar theory from Monash University, found evidence in old papers which suggests that some stars do not follow the pattern as they should follow according to science. Until now, scientists believed that mass stars similar to the Sun pass through a phase at the end of their lives that would occur in a huge burning of nuclear fuel, which would cause much of the mass of the stars were lost in the form of dust and gases.
This process causes the stars to get in the asymptotic giant branch (AGB), the name of a region in the Hertzsprung-Russell diagram, which shows the evolution of lo w and medium mass stars. In visual terms, a star in this AGB has the appearance of a red giant (RGB). However, observations made with the Very Large Telescope (VLT) of ESO (European Southern Observatory), focusing on a giant star cluster show that most stars there simply has not reached this stage during their evolution.
- Simon Campbell, Australian stellar theory expert.
Campbell then led a team of research that used the VLT to the complete study of the radiation emitted by stars of the star cluster NGC 6752, which is located in the southern constellation of Pavo the Peacock.
This brings a huge constellation of first generation and second generation stars, formed shortly after. Both generations can be identified according to the amount of light chemical elements such as nitrogen, carbon and for this study sodium.
Star cluster NGC 6752 seen by VLTImage
To the scientists' surprise, all AGB stars in the study were first generation, while none of the stars of the second generation - those containing higher levels of sodium - had become an AGB. About 70% of the stars are not found in the stage of final burning of nuclear material.
I.E. these stars die much earlier than was estimated and without helium burning when the star begins to emit a very strong light. These results provide a high impact, not only in theory but also in observational designs of stars - including the Sun. This means that the stars should be becoming too bright when reaching the final stage of their lives, which they simply do not.
- Campbell concludes.
The team is already planning new observations and the researchers believe that similar results will be found in other star clusters. With the new observation, there is a chance that the stars jumping into AGB phase evolve directly into white dwarfs with helium.
For now, the phenomenon remains a mystery and scientists do not believe that sodium alone is the cause of behavior contrary to the theories taken as concrete today.