The study of the "Demon star", Algol, made by a research group ofthe University of Helsinki, Finland, has received both scientificand public attention. The period of the brightness variation ofthis eclipsing binary star has been connected to good prognosesthree millennia ago. This result has raised a lot of discussion andthe news has spread widely in the Internet. The Egyptian papyrus Cairo 86637 calendar is probably the oldestpreserved historical document of bare eye observations of avariable star. Each day of one Egyptian year was divided into threeparts in this calendar. |
A good or a bad prognosis was assigned forthese parts of a day. + The texts regarding the prognoses are connected to mythologicaland astronomical events, says Master of Science Sebastian Porceddu. A modern period analysis revealed that two statisticallysignificant periods of 29.6 and 2.850 days have been recorded intothe good prognoses. The former is clearly the period of the Moon.The second period differs slightly from the period Algol.
In thiseclipsing binary, the dimmer star partially covers the brighterstar with a period of 2.867 days. + These eclipses last about ten hours and they can be easilyobserved with bare eyes. Their period was discovered by Goodrickein the year 1783, says docent Lauri Jetsu. + We can explain why the period of Algol has increased by about0.017 days, says Lauri Jetsu. The period increase during the pastthree millennia could have been caused by the observed masstransfer between the two members of this binary.
In fact, thiswould be the first observation that confirms the period increase ofAlgol and it also gives an estimate of the mass transfer rate. The ancient Egyptians have made accurate measurements that provideuseful constraints for modern astronomers. + It seems that the first observation of a variable star was made3000 years earlier than was previously thought, says Lauri Jetsu.However, I want to emphasize that our research has only been sentto a scientific journal about two weeks ago. This type of resultscan raise a lot of controversy before they are accepted.
The research was made in collaboration by the researchers from theDepartment of Physics and the Department of World Cultures of theUniversity of Helsinki. It has been published electronically in thearXiv on April 30th, 2012. The Egyptology part of the research willbe published separately. Did the ancient egyptians record the period of the eclipsing binaryAlgol - the Raging one? L. Jetsu, S.
Porceddu, J. Lyytinen, P. Kajatkari, J. Lehtinen, T.Markkanen, J.
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