Figure showing the different size scales of accreting objects. Credit: Simone Scaringi
Accretion is the growth in mass of an object by gravitationally collecting material from its surroundings. “In our paper (Astrophysical accretion is a universal process in objects from proto-stars to supermassive black holes), we discovered a relationship that spans the range of different types of accreting objects, from proto-stars, much like our sun was at its time of birth, to white dwarfs to supermassive black holes with a billion times the mass of the sun located in galaxies millions of light-years away,” Maccarone said.
“In these systems there is some characteristic timescale for the variability – typically the large brightenings and fadings occur with that timescale. What we have found is that 2 important properties of the object are its physical size scale and the rate at which it is accreting matter.”
The paper discussed a unified scenario for understanding brightness variations from accretion disks around different types of stars and stellar remnants. Previous work unified the variability in disks around black holes of different mass ranges, but now scientists can bring in accreting white dwarfs and even proto-stars by considering not just the mass of the star but also its size.
“Interestingly, there is no evidence the mass of the object affects the timescale,” Maccarone said. “That the objects all fit on a universal scale suggests that the process of infall of matter is a universal process. Until recently, there has been relatively little discussion between the scientists who try to understand how proto-stars grow and the scientists who try to understand how supermassive black holes grow, but these findings suggest that there should be.”
http://advances.sciencemag.org/content/1/9/e1500686 http://phys.org/news/2015-10-paper-little-understood-astronomy.htmljCp
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