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Henrietta Leavitt, a pioneer in the study of the Universe


job Astronomical Observatory of Teramo piu'di 10 years and for most of this period I accupata the study of variable stars.
The behavior of this class of stars, in turn composed of many sub-classes, has for many years an important test of our understanding of stellar evolution.
Also, thanks to the intuition of an astronomer of the last century, their study has allowed us to relate readily observable quantities, such as the pulsation period, with their absolute magnitude and then to use these stars as a group of indicators away.
I am pleased to tell the story on this blog, perhaps little known, Miss Henrietta Leavitt and its fundamental discovery that has just turned a century old.
In the early decades of the last century, ie 'was whether the universe was represented only by the Milky Way or whether it was complex and endlessly piu'grande, Henrietta Leavitt after graduating worked in
astronomy at the Observatory of the University 'Harvard University.
His job, as for other women used computers as human, on photographic plates to measure the movement of objects photographed and their magnitudes.
In 1908, Miss Leavitt had examined plates collected between 1893 and 1906 of the Magellanic Clouds produced a catalog of piu'di one thousand variables. For about 20 of these data were sufficient to determine the period of their variation in brightness'. Miss Leavitt observe 'that the more' variables were much more brilliant 'was their long-term. Leavitt
including the variables of the Small Magellanic Cloud showed evidence of a regolarita'che not observed in other regions of the sky 'cause those variables were all at the same distance from Earth, a distance that pero'non you know.
not escape the 'scope of his discovery, because I hope' that the parallax of a variable of this class (called Cepheids in the future) could be measured to calibrate the relationship that would allow them to measure the absolute magnitude of each object by only pulsazionale period.
His discovery enabled him to calculate distances between 100 and 10 million light-years thus opening 'the way the basic work of Hubble and Shapley who revolutionized our understanding of the Galaxy and on the 'Universe, while the period-luminosity relation' of the Cepheids is still the foundation of our scale of extragalactic distances.
Perhaps because of his untimely death in 1921 his name was not received the recognition he deserved in the community 'science of the time.
The fundamental contribution of this young woman, the result of his insight and dedication, 'but now well recognized, and was recently celebrated the centenary of his discovery with a congress, whose posters carry the head in these lines.

Anna Piersimoni