Orion Nebula, Pleiades and Hyades reveal the development of star clusters
The Orion Nebula, the Hyades and the Pleiades are visible to the naked eye. The star clusters are obviously examples of different stages of development.
The three star clusters in the night sky
(Image: Aladin sky atlas/CDS Strasbourg Observatory (France))
The fact that the Orion Nebula, the Pleiades, and the Hyades are in the same direction in the sky is possibly no coincidence. This is the opinion of a German-Iranian research group, which has determined that the three star clusters represent different stages of development and that we see one and the same object “as a baby, a teenager and an old man”. According to co-author Pavel Kroupa from the University of Bonn, it seems as if the same people are born again and again. In any case, the work now presented suggests “that star clusters such as the Orion nebula cluster go through a development path that transforms them into systems such as the Pleiades and later into the Hyades,” says his colleague Hosein Haghi.
Three star clusters, one evolutionary history
As the team explains, the work is based on “high-precision stellar dynamics calculations,” according to which all three star clusters originate from one and the same predecessor model. The differences are therefore because the Orion Nebula Cluster is extremely young at 2.5 million years, the Pleiades – the “Pleiades”– are much older at 100 million years, and the Hyades are downright old at 700 million years. With increasing age, the stars they contain become more and more scattered, which can be seen here. The star clusters therefore lose gas and stars to their surroundings. According to the simulations, this happens in such a way that the three star clusters exactly represent the respective development time.
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The team led by Ghasem Safaei from the Iranian Institute for Advanced Studies in Basic Sciences also believes that the structures visible to the naked eye are not positioned so closely together in the night sky by chance. This positioning could therefore be related to how star clusters form in the Milky Way and also develop under the influence of its gravity. Their work should now help to refine the models for the formation and development of stars. It has now been published in the Monthly Notices of the Royal Astronomical Society.
(mho)
