SA telescopes unveil 580-year old mystery around star

Scientists have used two South African telescopes to help figure out a 580-year old mystery surrounding the sighting of a bright and short-lived star in the tail of the constellation Scorpius in ancient Korea.

Modern astronomers already knew from the records made by Korean astronomers in 1437 that the star‚ which was seen for a mere 14 days‚ was a nova explosion. But until now they were unable to determine the location of the binary star system that caused it.

Figuring out that puzzle has helped deepen scientists’ understanding of how binary star systems and their nova eruptions change over time‚ and supports the idea that novae have a very long life cycle. After erupting they fade into obscurity for thousands of years and then slowly build back up to become novae again.

A nova is a massive explosion created by a dead star‚ known as a white dwarf‚ and a bright‚ sun-like star. The dwarf star cannibalises hydrogen from the sun-like star‚ creating a thin layer that eventually reaches a critical temperature and explodes in a burst of light. The star can be up to 300‚000 times brighter than the sun for up to several months.

“The real challenge in understanding the evolution of these systems is that unlike watching (an) egg transform into the eventual butterfly‚ which can happen in just a month‚ the life cycle of a nova is hundreds of thousands of years. We simply haven’t been around long enough to see a single complete cycle‚” said Lisa Crause from the South African Astronomical Observatory (SAAO) and co-author of a paper describing the research published on Thursday in the peer review journal Nature.

Scientists used information gleaned from the records made by Korean astronomers in 1437‚ photographic plates taken in the 1920s and 1940s at the Harvard Observatory station in Peru‚ and more recent optical telescopes in South Africa and Chile to locate the binary star that produce the nova eruption.

They used both the Southern African Large Telescope (SALT) and the South African Astronomical Observatory’s new 1 metre telescope in their research.