The NASA-ESA Hubble Space Telescope has succeeded in observing and measuring a cluster of young stars in the Milky Way moving at a uniform speed of 4.5 kilometers per second.
German scientists from the Max Planck Institute for Astronomy and the University of Cologne compared observations of the nebula NGC 3603 taken in 1997 with others obtained in 2007 using the same camera and filter. In 234 of the 800 stars observed, astronomers were able to measure the speed with sufficient precision, according to the Astrophysical Journal . "Our measurements are accurate to 27 millionths of an arc second per year . This tiny angle corresponds to the apparent diameter of a human hair seen from 800 kilometers away," explains Boyke Rochau, co-author of the study.
From the observations, the astronomers conclude that, contrary to expectations, the speeds of the stars are independent of their mass , and that they still reflect the conditions existing at the time of their formation, about a million years ago. when a gigantic cloud of gas and dust collapsed.
With a mass of more than 10,000 suns packed into a volume whose diameter is only 3 light years, the young star cluster observed in NGC 3603 is the most compact in the Milky Way . In comparison, in the vicinity of the Earth the same volume contains a single star, the Sun.
